PowerLab Teaching Series Owner's Guide (15T, 26T, 2/26, 4/26) Power Lab OG

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PowerLab®
Teaching Series
Owner’s Guide

This document was, as far as possible, accurate at the time of release. However, changes
may have been made to the software and hardware it describes since then.
ADInstruments Pty Ltd reserves the right to alter specifications as required. Latebreaking information may be supplied separately.
Trademarks of ADInstruments
PowerLab®, LabChart®, LabTutor®, LabAuthor® and MacLab® are registered trademarks of
ADInstruments Pty Ltd. The names of specific recording units, such as PowerLab 15T, are
trademarks of ADInstruments Pty Ltd. LabTutor Server, Chart and Scope (application
programs) and LabTutor Online are trademarks of ADInstruments Pty Ltd.
Other Trademarks
Apple, Mac and Macintosh are registered trademarks of Apple Computer, Inc.
Windows, Windows 7 and Windows Vista are either registered trademarks or
trademarks of Microsoft Corporation.
All other trademarks are the property of their respective owners.

Product: ML818 PowerLab 15T, ML826 PowerLab 2/26, ML846 PowerLab 4/26 and
ML856 PowerLab 26T
Document Number: U-ML818/OG-003F
Part Number: 5352
Copyright © 2014 ADInstruments Pty Ltd.
Unit 13, 22 Lexington Drive, Bella Vista, NSW 2153, Australia
All rights reserved. No part of this document may be reproduced by any means without
the prior written permission of ADInstruments Pty Ltd.
Web: www.adinstruments.com
Technical Support: support.au@adinstruments.com
Documentation: documentation@adinstruments.com
ADInstruments Pty Ltd. ISO 9001:2000 Certified Quality Management System
Reg. No. 1053

ii

PowerLab Owner’s Guide

Contents

Safety Notes

5

1 Overview
How to Use This Guide . . . . . . . . . . . . .
Software Installation . . . . . . . . . . . . . .
PowerLab Check. . . . . . . . . . . . . . . . .
The PowerLab . . . . . . . . . . . . . . . . . .
The Front Panel . . . . . . . . . . . . . . .
Indicators . . . . . . . . . . . . . . . .
Trigger . . . . . . . . . . . . . . . . . .
Analog Output . . . . . . . . . . . . .
Analog Inputs . . . . . . . . . . . . . .
Isolated Stimulator . . . . . . . . . . .
The Bio Amp Inputs (Inputs 3 and 4)
The Back Panel . . . . . . . . . . . . . . .
Audio Connector . . . . . . . . . . .
I2C Connector . . . . . . . . . . . . .
USB Connector . . . . . . . . . . . .
Digital Input and Output Connectors
Ground Connector . . . . . . . . . . .
Power Connector . . . . . . . . . . .
The Bio Amp Cable . . . . . . . . . . . . . . .
Other ADInstruments Hardware . . . . . . .

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2 Setting Up
The PowerLab Self-test . . . . . . . . . . . . . . .
Connecting the PowerLab . . . . . . . . . . . . .
ADInstruments Software . . . . . . . . . . . . . .
LabTutor Software . . . . . . . . . . . . . . .
LabChart Software . . . . . . . . . . . . . . .
The Isolated Stimulator . . . . . . . . . . . .
Choosing How Stimulation Should Start
Choosing a Stimulus Type . . . . . . . . .
Creating a Custom Stimulus Waveform .
Contents

. 12
. 12
. 12
. 13
. 13
. 13
. 13
. 15
. 15
. 16
. 16
. 17
. 18
. 18
. 18
. 18
. 19
. 19
. 19
. 20

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. 22
. 23
. 23
. 23
. 23
. 24
. 24
. 26
. 26
iii

Setting Stimulus Parameters
Marker Channel . . . . . . .
The Stimulator Panel . . . .
The Bio Amp . . . . . . . . . . .
Signal Display . . . . . . . .
Setting the Range . . . . . .
Filtering . . . . . . . . . . .
Inverting the Signal . . . . .
Units . . . . . . . . . . . . .

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A Technical Aspects
How it Works . . . . . . . . . . . . .
The Analog Inputs . . . . . . . .
The Analog Outputs . . . . . .
The External Trigger . . . . . .
Bio Amp Input (Inputs 3 & 4) .
The Isolated Stimulator Output
PowerLab Accuracy . . . . . . .
Connectors . . . . . . . . . . . . . .
Digital Input and Output . . . .
I2C Expansion Connector . . . .
Input Connectors . . . . . . . .
USB Connection
. . . . . . .
Earthing and Ground Loop Noise .

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26
27
27
28
28
28
29
31
31

33

B Specifications

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34
35
35
36
37
38
39
39
39
40
41
41
42

43

Analog Inputs . . . . . . . . . . . . . . . . . . . . . . .
Pod Connectors (DIN) . . . . . . . . . . . . . . . . . .
Sampling . . . . . . . . . . . . . . . . . . . . . . . . . .
Bio Amp Input – Inputs 3 & 4 (PowerLab 15T & 26T)
Output Amplifier . . . . . . . . . . . . . . . . . . . . .
Isolated Stimulator Output (PowerLab 15T & 26T) . .
External Trigger (not on PowerLab 15T) . . . . . . . .
Expansion Ports (not on PowerLab 15T) . . . . . . . .
Microprocessor and Data Communication . . . . . . .
Physical Configuration . . . . . . . . . . . . . . . . . .
Operating Requirements . . . . . . . . . . . . . . . . .
Electromagnetic Compatibility . . . . . . . . . . . . . . . .
Emissions . . . . . . . . . . . . . . . . . . . . . . . . . .
Immunity . . . . . . . . . . . . . . . . . . . . . . . . . .
Separation Distances . . . . . . . . . . . . . . . . . . .

iv

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43
44
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46
46
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48
48
48
48
50

C Glossary

51

Index

57
PowerLab Owner’s Guide

Safety Notes

Statement of Intended Use
All products manufactured by ADInstruments are intended for use in
teaching and research applications and environments only. ADInstruments
products are NOT intended to be used as medical devices or in medical
environments. That is, no product supplied by ADInstruments is intended to
be used to diagnose, treat or monitor a subject. Furthermore no product is
intended for the prevention, curing or alleviation of disease, injury or
handicap.
Where a product meets IEC 60601-1 it is under the principle that:
•
•

it is a more rigorous standard than other standards that could be chosen,
and
it provides a high safety level for subjects and operators.

The choice to meet IEC 60601-1 is in no way to be interpreted to mean that a
product:
•
•
•

Safety Notes

is a medical device,
may be interpreted as a medical device, or
is safe to be used as a medical device.

5

Safety Symbols
Devices manufactured by ADInstruments that are designed for direct
connection to humans are tested to IEC 601-1:1998 (including amendments 1
and 2) and 60601-1-2, and carry one or more of the safety symbols below.
These symbols appear next to those inputs and output connectors that can be
directly connected to human subjects.

!
BF symbol: Bodyprotected equipment

CF symbol: Cardiacprotected equipment

Warning symbol: ‘see
documentation’

The three symbols are:
•

•

•

BF (body protected) symbol. This means that the input connectors are
suitable for connection to humans provided there is no direct electrical
connection to the heart.
CF (cardiac protected) symbol. This means that the input connectors are
suitable for connection to human subjects even when there is direct
electrical connection to the heart.
Warning symbol. The exclamation mark inside a triangle means that the
supplied documentation must be consulted for operating, cautionary or
safety information before using the device.

Further information is available on request.

Bio Amp Safety Instructions
The Bio Amp inputs displaying any of the safety symbols are electrically
isolated from the mains supply in order to prevent current flow that may
otherwise result in injury to the subject. Several points must be observed for
safe operation of the Bio Amp:
•

6

All Bio Amp front-ends (except for the ML138 Octal Bio Amp) and
PowerLab units with a built-in Bio Amp are supplied with a 3-lead or 5-

PowerLab Owner’s Guide

•

•

lead Bio Amp subject cable and lead wire system. The ML138 Octal Bio
Amp is supplied with unshielded lead wires (1.8 m). Bio Amps are only
safe for human connection if used with the supplied subject cable and lead
wires.
All Bio Amp front-ends and PowerLab units with a built-in Bio Amp are
not defibrillator-protected. Using the Bio Amp to record signals during
defibrillator discharges may damage the input stages of the amplifiers.
This may result in a safety hazard.
Never use damaged Bio Amp cables or leads. Damaged cables and leads
must always be replaced before any connection to humans is made.

Isolated Stimulator Safety
Instructions
The Isolated Stimulator outputs of a front-end signal conditioner or PowerLab
with a built-in isolated stimulator are electrically isolated. However, they can
produce pulses of up to 100 V at up to 20 mA. Injury can still occur from
careless use of these devices. Several points must be observed for safe
operation of the Isolated Stimulator:
•
•
•
•
•

•

•
•
•
•

Safety Notes

The Isolated Stimulator output must only be used with the supplied bar
stimulus electrode.
The Isolated Stimulator output must not be used with individual
(physically separate) stimulating electrodes.
Stimulation must not be applied across the chest or head.
Do not hold one electrode in each hand.
Always use a suitable electrode cream or gel and proper skin preparation
to ensure a low-impedance electrode contact. Using electrodes without
electrode cream can result in burns to the skin or discomfort for the
subject.
Subjects with implantable or external cardiac pacemakers, a cardiac
condition, or a history of epileptic episodes must not be subject to
electrical stimulation.
Always commence stimulation at the lowest current setting and slowly
increase the current.
Stop stimulation if the subject experiences pain or discomfort.
Do not use faulty cables, or those that have exhibited intermittent faults.
Do not attempt to measure or record the Isolated Stimulator waveform
while connected to a subject using a PowerLab input or any other piece of
equipment that does not carry the appropriate safety symbol (see Safety
Symbols above).
7

Always check the status indicator on the front panel. It will always flash green
each time the stimulator delivers a current pulse. A yellow flash indicates an
‘out-of-compliance’ (OOC) condition that may be due to the electrode contact
drying up. Always ensure that there is good electrode contact at all times.
Electrodes that are left on a subject for some time need to be checked for dry
contacts. An electrode impedance meter can be used for this task.
•

•

Always be alert for any adverse physiological effects in the subject. At the
first sign of a problem, stimulation must be stopped, either from the
software or by flicking down the safety switch on the front panel of any
built-in Isolated Stimulator or the ML180 Stimulus Isolator.
The ML180 Stimulus Isolator is supplied with a special transformer plug
pack. The plug pack complies with medical safety requirements.
Therefore, under no circumstances should any other transformer be used
with the Stimulus Isolator. For a replacement transformer plug pack please
contact your nearest ADInstruments representative.

General Safety Instructions
To achieve the optimal degree of subject and operator safety, consideration
should be given to the following guidelines when setting up a PowerLab
system either as stand-alone equipment or when using PowerLab equipment
in conjunction with other equipment. Failure to do so may compromise the
inherent safety measures designed into PowerLab equipment. The following
guidelines are based on principles outlined in the international safety
standard IEC60601-1-1: General requirements for safety - Collateral standard:
Safety requirements for medical systems. Reference to this standard is required
when setting up a system for human connection.
PowerLab systems (and many other devices) require the connection of a
personal computer for operation. This personal computer should be certified
as complying with IEC60950 and should be located outside a 1.8 m radius
from the subject (so that the subject cannot touch it while connected to the
system). Within this 1.8 m radius, only equipment complying with IEC606011 should be present. Connecting a system in this way obviates the provision of
additional safety measures and the measurement of leakage currents.
Accompanying documents for each piece of equipment in the system should
be thoroughly examined prior to connection of the system.
While it is not possible to cover all arrangements of equipment in a system,
some general guidelines for safe use of the equipment are presented below:

8

PowerLab Owner’s Guide

•
•

•
•
•

•

•

•

•

•

Any electrical equipment which is located within the SUBJECT AREA
should be approved to IEC60601-1.
Only connect those parts of equipment that are marked as an APPLIED
PART to the subject. APPLIED PARTS may be recognized by the BF or CF
symbols which appear in the Safety Symbols section of these Safety Notes.
Only CF-rated APPLIED PARTS must be used for direct cardiac
connection.
Never connect parts which are marked as an APPLIED PART to those
which are not marked as APPLIED PARTS.
Do not touch the subject to which the PowerLab (or its peripherals) is
connected at the same time as making contact with parts of the PowerLab
(or its peripherals) that are not intended for contact to the subject.
Cleaning and sterilization of equipment should be performed in
accordance with manufacturer’s instructions. The isolation barrier may be
compromised if manufacturer’s cleaning instructions are not followed.
The ambient environment (such as the temperature and relative humidity)
of the system should be kept within the manufacturer’s specified range or
the isolation barrier may be compromised.
The entry of liquids into equipment may also compromise the isolation
barrier. If spillage occurs, the manufacturer of the affected equipment
should be contacted before using the equipment.
Many electrical systems (particularly those in metal enclosures) depend
upon the presence of a protective earth for electrical safety. This is
generally provided from the power outlet through a power cord, but may
also be supplied as a dedicated safety earth conductor. Power cords should
never be modified so as to remove the earth connection. The integrity of
the protective earth connection between each piece of equipment and the
protective earth should be verified regularly by qualified personnel.
Avoid using multiple portable socket-outlets (such as power boards)
where possible as they provide an inherently less safe environment with
respect to electrical hazards. Individual connection of each piece of
equipment to fixed mains socket-outlets is the preferred means of
connection.

If multiple portable socket outlets are used, they are subject to the following
constraints:
•
•
•

Safety Notes

They shall not be placed on the floor.
Additional multiple portable socket outlets or extension cords shall not be
connected to the system.
They shall only be used for supplying power to equipment which is
intended to form part of the system.

9

Cleaning and Sterilization
ADInstruments products may be wiped down with a lint free cloth moistened
with industrial methylated spirit. Refer to the manufacturer’s guidelines or the
Data Card supplied with transducers and accessories for specific cleaning and
sterilizing instructions.

Preventative Inspection and
Maintenance
PowerLab systems and ADInstruments front-ends are all maintenance-free
and do not require periodic calibration or adjustment to ensure safe
operation. Internal diagnostic software performs system checks during power
up and will report errors if a significant problem is found. There is no need to
open the instrument for inspection or maintenance, and doing so within the
warranty period will void the warranty.
Your PowerLab system can be periodically checked for basic safety by using
an appropriate safety testing device. Tests such as earth leakage, earth bond,
insulation resistance, subject leakage and auxiliary currents and power cable
integrity can all be performed on the PowerLab system without having to
remove the covers. Follow the instructions for the testing device if performing
such tests.
If the PowerLab system is found not to comply with such testing you should
contact your PowerLab representative to arrange for the equipment to be
checked and serviced. Do not attempt to service the device yourself.

Environment
Electronic components are susceptible to corrosive substances and
atmospheres, and must be kept away from laboratory chemicals.
Storage Conditions

•
•

Temperature in the range 0–40 °C
Non-condensing humidity in the range 0–95%.

Operating Conditions

•
•

Temperature in the range 5–35 °C
Non-condensing humidity in the range 0–90%.

Disposal

•

10

Forward to recycling center or return to manufacturer.

PowerLab Owner’s Guide

Overview

1

Your PowerLab® recording unit, together with a range of specialized
application programs, provides a versatile data recording and analysis system
when used with a Windows or Macintosh computer. This chapter provides an
overview of the PowerLab system and describes the basic features, connectors
and indicators of the PowerLab.

Note that the software supplied with the PowerLab should be installed before
you connect the PowerLab to your computer.

Chapter 1 Overview

11

How to Use This Guide
This owner’s guide describes how to set up and begin using your PowerLab
recording unit. The chapters provide an overview of the PowerLab system (the
combined software and hardware package), and a more detailed look at the
features of your recording unit and its connection to your computer. The
appendices provide technical information about the recording unit and
solutions to problems. At the end of this guide is a glossary of hardware terms
and an index.

Software Installation
You should install ADInstruments application software before connecting or
using your PowerLab.
The Getting Started with LabTutor manual provides full installation
instructions for the LabTutor software.
The Getting Started with PowerLab manual provides full installation
instructions for the LabChart and Scope software.

PowerLab Check
Please do not attempt to connect the PowerLab to a power outlet or computer
or turn it on until you have checked it as described below.
1. Check that all items in the accompanying packing list are included in the
box.
2. Check that there are no obvious signs of external damage to the PowerLab.
3. Check that there are no obvious signs of internal damage, such as rattling.
Pick up the PowerLab, tilt it gently from side to side, and listen for
anything that appears to be loose.
If anything is missing, or the PowerLab seems to be damaged in any way,
contact your authorized ADInstruments representative immediately. Up-todate contact addresses are available from the ADInstruments website.
Connection information is in Chapter 2.

12

PowerLab Owner’s Guide

The PowerLab
This section describes the connectors and indicators of the PowerLab 15T,
2/26, 4/26 and 26T.

The Front Panel
The front panel (Figure 1–1 to Figure 1–4) provides the connectors for
obtaining external signals, and indicators for various functions. This section
describes each of the front panel features:
•
•
•
•
•

Power and Status indicator LEDs
Trigger indicator LED and BNC connector (not on PowerLab 15T)
Output BNC connectors
Input DIN connectors
Input BNC connectors (PowerLab 2/26 and 4/26 only)

For the PowerLab 15T and 26T:
•
•

Isolated Stimulator switch, indicator LEDs and output connectors
Bio Amp connector.

Indicators

The Power and Status indicators on the front panel should flash briefly while
the PowerLab is starting up. Under normal conditions, the Power indicator
should glow blue and stay lit. This simply shows that the PowerLab is getting
power.
The Status indicator should flash yellow and then stay green when the
PowerLab is switched on, and again when an ADInstruments application is
opened. It provides some visual indication of what the PowerLab is doing, and
will flash different patterns and colors depending on the state of the
PowerLab. See Table 2–1 for details.
Trigger

The external trigger connector of the PowerLab 2/26, 4/26 and 26T allows you
to use an external signal to synchronize recording to an external event. This
input can handle voltages of up to ±12 V. The threshold voltage (the voltage
above which the trigger circuit activates) is 2.0 volts for a rising edge. When
the trigger threshold is crossed, the indicator beside the external trigger
connector will glow yellow. The external trigger is described in more detail in
Appendix A, and the software documentation covers its practical use in
normal recording.

Chapter 1 Overview

13

Figure 1–1
The front panel of the
PowerLab 15T

Power and
Status
indicators

Analog input
connectors

Analog output
connectors

Isolated Stimulator
connectors

Bio Amp
connector

Figure 1–2
The front panel of the
PowerLab 26T

Trigger indicator and connector

Figure 1–3
The front panel of the
PowerLab 2/26

Power and
Status
indicators

Trigger indicator
and connector

Analog output
connectors

Analog input
connectors

Figure 1–4
The front panel of the
PowerLab 4/26

14

PowerLab Owner’s Guide

Analog Output

The PowerLab can generate a stimulus voltage through its analog output
sockets (marked Output + and –), giving positive, negative, differential, or
independent stimuli, depending on the sockets used and the software settings.
By default, the outputs are used for complementary (differential) stimulation,
where Output + is positive and Output – is negative.
When Output + is used, a positive stimulus voltage (set up in the software)
gives a positive voltage output, and a negative voltage a negative one. When
Output – is used, the voltage outputs are inverted. When both output sockets
are used, the stimulus is the difference between the voltages at the positive
and negative outputs: you could generate up to a 20-volt pulse, using a setting
of ±10 V.
You can use either the analog output or the isolated stimulator, but not both at
once.
Analog Inputs

The analog inputs can record external signals from ±10 V down to the
microvolt (μV) range, without the need for additional external amplification.
Each analog input has an independently programmable gain amplifier with its
own filtering. Note that applying more than ±15 V to the analog inputs can
damage the circuitry.

SWARNING
PowerLab inputs and
outputs are not electrically
isolated (except for the
Bio Amp input and the
Isolated Stimulator outputs)
and so should never be
connected to human
subjects.

The PowerLab 15T and 2/26 have two independent analog inputs marked
Input 1 and 2; the PowerLab 26T and 4/26 have four such inputs marked 1–4.
These 8-pin DIN connectors and BNC connectors can be used as:
•
•
•

Single-ended inputs, where the difference between the signal and ground
is recorded.
Differential inputs, where the difference between the positive and negative
input signals is recorded.
Pod connectors, which allow the connection of ADInstruments pods, or
those transducers designed for direct connection.

On the 15T and /26 model PowerLabs, the impedance between the earthing
stud (ground connection) and the input connector grounds is close to zero.
Note that with the PowerLab 26T:
•

•

Chapter 1 Overview

ADInstruments front-ends, such as the ML221 Bridge Amp, can be used
with inputs 1 and 2 (but not inputs 3 or 4) by connecting them with the
DIN-to-BNC adaptor.
When an ADInstruments pod is connected to either input 3 or 4, the
corresponding Bio Amp input is turned off.
15

Isolated Stimulator

The PowerLab 15T and 26T have a built-in, isolated, constant-current pulse
stimulator that can be used for any general-purpose stimulation with humans.
The Isolated Stimulator section of the front panel has two output sockets, two
indicator lights and a safety switch. Note that you cannot use the analog
output and the isolated stimulator at the same time.
The stimulus output is supplied via two 4 mm shrouded banana sockets; the
left-hand (red) socket is positive, the right-hand (black) socket is negative.
These are designed for use with shrouded male 4 mm plugs (the shrouding is
to prevent accidental stimulation while fitting or removing the plugs). The bar
stimulus electrode supplied with the PowerLab uses such plugs.
The output is capable of supplying 100 V pulses at currents up to 20 mA, so it
should be treated with caution. The Isolated Stimulator Pulse indicator is an
LED that indicates the current status of the Stimulator. It will flash green for
every stimulus pulse, and may seem to glow green constantly at higher
stimulus frequencies. The OOC (out-of-compliance) indicator is a yellow
LED. When lit, it indicates that the output is overloaded or out of compliance
(compliance is the ability to supply voltage to meet the required current). This
means that the impedance of the tissue being stimulated is too high, or there
is a poor electrical connection (possibly due to electrode drying), and that the
Isolated Stimulator can no longer supply constant current stimulation. If this
should happen, try reducing the output current amplitude, and check all
connections.
To provide an additional level of safety, a safety switch is located on the front
panel to allow the output to be switched on and off as needed. The switch
should be flicked down to turn the output off: doing so disconnects the output
sockets from the internal circuitry, allowing connections to be made safely
while the PowerLab is on.
The Bio Amp Inputs (Inputs 3 and 4)

The PowerLab 15T and 26T have a connector for two Bio Amp inputs,
marked Bio Amp Input 3 & 4. These biological amplifiers perform electrically
isolated measurements of biological signals, such as electrocardiograms
(ECG) and electromyograms (EMG). The two Bio Amp inputs have a
common six-pin connector with a shared ground signal and are internally
configured to use channels 3 and 4 of the PowerLab.
The PowerLab comes supplied with a 5-lead Bio Amp cable and lead wires.
The Bio Amp inputs should only be used with the supplied Bio Amp cable
and approved leads. Other cables may not meet safety requirements. Note:
with the PowerLab 26T, connecting an ADInstruments pod to either analog
input 3 or 4 turns off the corresponding Bio Amp input.
16

PowerLab Owner’s Guide

The Back Panel
The back panels of the PowerLab (Figure 1–5 to Figure 1–7) provide the
sockets to connect the PowerLab to the computer, other devices and the
power outlet. This section describes each of the back panel features:
•

Audio connector (PowerLab 26T only)

•
•
•
•
•

I2C connector (not on PowerLab 15T)
USB connector
Digital input and output connectors (PowerLab 26T only)
Ground connector
Power switch and socket.

Figure 1–5
The back panel of the
PowerLab 15T

Audio connector USB connector

Digital Output Ground
connector

Device rating
information

Power switch
and socket

Device rating
information

Power switch
and socket

Figure 1–6
The back panel of the
PowerLab 26T

I2C connector

USB connector Digital Input
connector

Ground

Figure 1–7
The back panel of the
PowerLab 2/26 and 4/26

Chapter 1 Overview

17

Audio Connector

The PowerLab 26T has an audio output to monitor the Bio Amp channels. It
provides stereo sound (using signals from Inputs 3 and 4). The 3.5 mm stereo
socket can be used with a wide range of headphones or externally powered
speakers. The audio output is particularly helpful when monitoring nerve
firings, to assist in the placement of electrodes, for instance.
I2C Connector

The I2C output port (not on PowerLab 15T) provides power and control
signals for front-ends manufactured by ADInstruments.
Many front-ends can be daisy-chained together and connected through the
I2C ports, so long as there are enough analog inputs on the PowerLab. A
maximum current of 50 mA can be provided through this bus, so it should
not be used for third-party devices that require more current than that.
USB Connector

The PowerLab connects to your computer using a USB 2.0 connector and
cable, therefore your computer must have USB connectors or a PCI USB card
to receive data from the PowerLab.
You can safely disconnect or reconnect a USB-connected PowerLab while the
computer remains on. However, ADinstruments software (LabTutor,
LabChart or Scope) should not be running while you do this. Read the details
on USB in Appendix A of this guide before connecting your PowerLab to your
computer.
Digital Input and Output Connectors

The digital input and output ports (PowerLab 26T only) let you monitor and
control external devices, respectively, with the PowerLab.
The digital input monitors state changes: you can have a predefined comment
automatically inserted during recording when a digital input changes to a
particular state. The eight lines of the connector allow monitoring of up to
eight devices. The digital output can turn on and off external devices, for
example pumps, relays, and indicator lights, or can signal to some other
device. The eight lines of the connector allow control of up to eight devices.
Technical details of the digital input and output connectors are given in
Appendix A. Note that any cables connected to either the digital input or
output must be less than 3 m in length in order to maintain EMC compliance.
More information on the use of digital inputs and outputs is given in the Help
for the software.
18

PowerLab Owner’s Guide

Ground Connector

A special earthing (grounding) stud is provided on the rear panel of the
PowerLab. This is an equipotential bonding connection post compatible with
the DIN 42801 standard. The earthing stud is directly connected to the earth
pin of the power socket and the PowerLab chassis. It is used as a primary
earth connection (equipotential connection point) in situations that require
this type of connection, or if there is no ground provided via the power cord.
Safety standards in laboratories and similar environments may require
additional grounding protection when connecting equipment to human
subjects, and their relevant standards or guidelines should be observed.
Power Connector

The power switch on the back right of the PowerLab turns the PowerLab on
and off; the 3-pin IEC power socket is used to connect your PowerLab to a
power cable. The power supply is universal, and can use all common
international mains power supplies (100–240 V AC, 50/60 Hz).
The PowerLabs are not fitted with replaceable fuses. The power supply is
short-circuit protected, and should not damage the internal fuses unless a
major fault develops. If that happens, the unit must be returned for service by
qualified service personnel. Do not attempt to replace internal power supply
fuses yourself. For further assistance please contact your nearest
ADInstruments representative.

The Bio Amp Cable
Connections are made to the Bio Amp inputs using the supplied Bio Amp
cable and leads. The cable plugs into the six-pin input socket on the front
panel: a notch in the plug ensures that polarity is correct. Only the supplied
Bio Amp cable and leads should be used. Other cables may not meet safety
requirements. The PowerLab 26T and 15T are supplied with a 5-lead Bio Amp
cable and lead wires; it uses a shared ground signal for its Bio Amp channels.
The cable is of the sort often used for ECG or EMG work, a Tronomed D1540 cable, and has a cable yoke with five sockets for the leads.
The supplied leads click into place in the cable yoke, and have snap
connectors at the other end to connect to typical ECG electrodes. The leads
are color-coded for ease of identification.
ADInstruments supplies other types of lead wires that connect to the Bio
Amp cable yoke, such as EEG Flat Electrodes and dry earth straps. Also
available are disposable and reusable electrodes, electrode cream (for reusable

Chapter 1 Overview

19

electrodes), electrode paste, and abrasive gel for lightly abrading the skin
before the electrodes are attached.
Figure 1–8
The Bio Amp cable yoke,
with 5 leads attached

To electrodes

To Bio Amp input

Other ADInstruments Hardware
ADInstruments has a range of optional devices that can be connected to your
PowerLab. They extend the types of experiments you can conduct and the
data you can record, and include:
•

•

•

Pods — small, low-cost signal conditioners for specific tasks, for use with
precalibrated transducers, and which are automatically recognized by the
PowerLab and application software.
Front-ends — advanced signal conditioners which are automatically
recognized by the PowerLab and software, and which provide specialized
data acquisition features (not used with the PowerLab 15T).
Transducers — either for use with a specific pod, or which plug directly
into the PowerLab, depending on their type.

A PowerLab can usually have as many pods or transducers connected to it as
it has appropriate connectors. All are easily transferred between PowerLabs.
Full information on such hardware is available from your local
ADInstruments representative or from the ADInstruments website.

20

PowerLab Owner’s Guide

Setting Up

2

This chapter describes:
•
•
•

Chapter 2 Setting Up

The PowerLab’s internal self-test.
The USB connection between the PowerLab and the computer.
The software features specific to the built-in Isolated Stimulator and Bio
Amp.

21

The PowerLab Self-test
The PowerLab performs a diagnostic self-test each time it is switched on.
Before connecting it to the computer for the first time, you should test that
your PowerLab is functioning properly, as follows:
1. Connect the PowerLab to a power outlet using the power cable that came
with your unit. Turn on the power at the wall.
2. Turn on the power switch located on the rear of the unit, and observe the
Power and Status indicators on the front panel while the PowerLab is
starting up:
• The Power indicator should glow blue while the PowerLab is on.
• The Status indicator should flash yellow and then stay green.
If the Status indicator stays green, the internal diagnostic check has completed
successfully. The PowerLab can now be switched off and connected to the
computer.
Table 2–1
Status indicator codes

Status Indicator

Meaning

Off

Idle and not yet initialized by the software.

Green

Idle, initialized, and waiting for a command from the computer.

Yellow

Sampling, or communicating with the computer.

Four red flashes
then one yellow

The PowerLab has detected a low-level software or hardware
fault. It will repeat until the PowerLab is turned off.

Red flashes

The PowerLab has detected an internal fault during the
power-up test. It will repeat until the PowerLab is turned off.

If the Power indicator does not glow blue when the power switch is turned on,
then there is a problem with the power source, power cable or PowerLab itself.
Check the connections and cables.
If the Status indicator is flashing red, then the PowerLab has detected an error
during the self-test. Restarting the PowerLab should clear a temporary
problem.
If the PowerLab does not seem to be getting power, or the Status indicator
flashes red, even after restarting, refer to the ADInstruments website
(www.adinstruments.com/support/tsupport/education) or contact your
authorized ADInstruments representative. Do not attempt to repair the
PowerLab yourself.

22

PowerLab Owner’s Guide

Figure 2–1
USB Icon

Connecting the PowerLab
Use the USB cable supplied with your PowerLab to connect the USB port on
the back panel to the USB port on the computer, or to an active USB hub
connected to the computer (see Figure 2–2). USB ports and cables should be
marked with a trident-like icon (Figure 2–1). Further detail about USB
connections is provided on page 41 of Appendix A.

Figure 2–2
Connecting a PowerLab to
a computer with USB

USB icon
PowerLab

Computer or hub
connection

USB cable

ADInstruments Software
The integration of hardware and software in the PowerLab system allows all
hardware functions, including those of any connected signal conditioners, to
be controlled from within the software.

LabTutor Software
When the PowerLab is used with the LabTutor application, the LabTutor
experiments have pre-configured settings for the PowerLab, and for any signal
conditioners needed for the experiment. For more information about the
LabTutor application please refer to LabTutor 4 Suite Administrator’s Guide.

LabChart Software
When the PowerLab is used with the LabChart (or Scope) application, the
PowerLab functions are set up from within that software. The software
controls for most functions, such as sampling speed, are described in the

Chapter 2 Setting Up

23

documentation for LabChart (or Scope). For more information about the
LabChart application please refer to the LabChart Help.
The software controls specific to the signal conditioners built into the
PowerLab 26T and 15T (an Isolated Stimulator and two Bio Amps) are
described below.

The Isolated Stimulator
The PowerLab 26T and 15T have both normal and isolated outputs, and you
can switch between them in software. The Isolated Stimulator provides
software-controlled, isolated, constant-current pulse stimuli that can be used
with human subjects. The stimulis is produced at the outputs on the front
panel of the Stimulus Isolator. The stimulus is independent of the PowerLab
sampling rate and can be generated whether the PowerLab is sampling or not.
The stimulus is set up using the Stimulator dialog.
Choose Setup > Stimulator.... to display the Stimulator dialog (Figure 2–3).
This dialog is named Stimulus Isolator on the Macintosh (Figure 2–4). When
setting up the Stimulus Isolator, you:
•
•
•
•

Choose how stimulation should start.
Choose a preconfigured stimulus type or mode.
Optionally, on Windows, create a custom stimulus waveform.
Set stimulus parameters, such as start delay, pulse width and current
amplitude.

Scope has a different Stimulator dialog to that of LabChart: in the Stimulator
dialog you can choose Pulse and Multiple in the Mode pop-up menu (to
produce single or multiple pulses, respectively).
Note that if you connect a Stimulus Isolator front-end to a PowerLab 15T or
26/T, only the external stimulator is used.
Choosing How Stimulation Should Start

Stimulation can be set to start in different ways:
• When sampling starts: stimulation begins automatically when the
LabChart Start button is clicked, and continues until sampling stops. Use
the On and Off buttons to control pulse delivery, if necessary.
• Manually: stimulation begins when Stimulate in the dialog is clicked, and
continues until sampling stops. Use the On and Off buttons to control
pulse delivery, if necessary.
• Independently of sampling: stimulation begins when On in the dialog is
clicked, whether or not LabChart is sampling. Available in LabChart for
Windows only.

24

PowerLab Owner’s Guide

Figure 2–3
The Stimulator dialog,
Windows

Choose how stimulation should start

Choose a stimulus
type preset

Specify a custom
stimulus
waveform
Configure the
range of valid
parameter values
in the Parameter
Settings dialog
Set stimulus
parameters

Turn stimulation on
(Pulse) or off

Mark the stimulus
event in a channel
Set the number
of pulses to be
delivered

Figure 2–4
The Stimulus Isolator
dialog, Macintosh

Click to start a
train of pulses
(when sampling
and manual start
is selected)
Check to set the
interval between
pulse starts

Change the stimulus frequency range

In all three modes, you can immediately restart a stimulus waveform by
clicking Stimulate.

Chapter 2 Setting Up

25

Choosing a Stimulus Type

The Stimulator only offers the Isolated Pulse stimulation mode (Pulse on
Macintosh). This generates a rectangular pulse stimulus that starts at zero
current, is raised to the set current amplitude for the set pulse width
(duration), and then falls to zero current again. By default, the stimulator is
off and the current amplitude is set to zero.
Creating a Custom Stimulus Waveform

In LabChart for Windows, you can:
• Specify whether parameter controls are displayed in the Stimulator and
Stimulator Panel dialogs.
• Define a sequence of segments to create a custom stimulus waveform.
Click Custom... to display the Waveform Customization dialog. Further
details about using this dialog are available in the LabChart Help.
Setting Stimulus Parameters

You use the text boxes and sliders to set values for the stimulus parameters. In
LabChart for Windows, you can use the Settings dialog for each parameter to
configure the range of values available to the parameter text box and slider
controls. Using suitable values can improve the precision of control over the
stimulus parameter when using the slider and spinner controls.
Windows
In LabChart for Windows, the following stimulus parameters can be set:
Start Delay: the wait time before stimulation is delivered, once the stimulus

waveform has been started.
Repeats: the number of times the stimulus waveform is repeated, once

started.
Max Repeat Rate: the maximum frequency with which the stimulus
waveform is repeated (either 0.1—20 Hz or 6—1200 /min), or the interval
between each pulse start (0.05—10 s).
Pulse Width: the duration of each pulse. The pulse duration is restricted to the
range from 50 μs to 200 μs for safety reasons.
Current: the amplitude of the stimulus current (0 to 20 mA).
End Delay: the wait time at the end of a stimulus segment, after which the

next segment is delivered. This is not the same as a Delay segment.
Macintosh
In LabChart for Macintosh, the following stimulus parameters can be set:
26

PowerLab Owner’s Guide

Range: lets you select the range for the Frequency control; either 0.1—2 Hz,

0.1—20 Hz, or 2—200 PPM (~0.033 Hz to ~3.3 Hz). PPM (pulses per minute)
can sometimes be a more convenient expression of the pulse frequency.
Frequency: the rate at which pulses are delivered; available values are within
those set with Range.
Pulse duration: the time for which the pulse lasts, from 50 μs to 200 μs

(0.05 ms to 0.2 ms). The pulse duration is limited to 200 μs for safety reasons.
Amplitude: the exact amplitude of the stimulus current, from 0 to 20 mA.

Marker Channel

If you choose a channel from the Marker Channel pop-up menu, then the
start time of a stimulus pulse is marked by a small data spike (this adds to any
data in that channel).
The Stimulator Panel

Once you have set up stimulation using the Stimulator dialog, you can easily
start or stop stimulation or change settings while sampling, by using the
Stimulator Panel. Choose Stimulator Panel from the Setup menu to open it
(Stimulus Isolator Panel on Macintosh).
On Windows, you can specify which parameter controls are displayed in the
panel using checkboxes in the Panel column of the Waveform Customization
dialog. See the LabChart Help for details.
The Stimulator Panel ‘floats’ in front of the active window, can be moved
around with its title bar, and can only be dismissed by clicking its close box.
Figure 2–5
The Stimulator Panel
Windows (upper)
Macintosh (lower): manual
control of stimuli

This button appears when
manual stimulation is selected

Chapter 2 Setting Up

27

The Bio Amp
The PowerLab 26T and 15T have two-channel Bio Amps, which are internally
configured to use channels 3 and 4. The Bio Amp dialog allows software
control of the combined input amplifiers and filters in the PowerLab and Bio
Amps. The signal present at a channel’s input is displayed so that you can see
the effects of changes straight away. Once settings in the dialog are changed,
click OK to apply them.
The Bio Amp dialog appears when you choose Bio Amp… from a Channel
Function pop-up menu (or click Bio Amp… in the Input Settings column in
the Channel Settings dialog). To set up many channels quickly, click the
arrows by the dialog title, or press the right or left arrow keys on the
keyboard, to move to the equivalent dialogs for adjacent channels. This skips
channels that are turned off. The channel number is shown next to the arrows,
and the channel title
(if any) is shown in the vertical Amplitude axis of the dialog.
Signal Display

The input signal is displayed so you can see the effect of changing the settings
— no data is recorded while the Bio Amp dialog is open. Slowly changing
waveforms will be represented quite accurately, whereas rapidly changing
signals will be displayed as a solid dark area showing only the envelope
(shape) of the signal formed by the minimum and maximum recorded values.
The average signal value is shown at the top left of the display area.
You can stop the signal scrolling by clicking the Pause button at the bottom
left (Macintosh) or top right (Windows) of the data display area. This changes
to the Scroll button on the Macintosh. Click the Scroll button to start scrolling
again.
Shift and stretch the vertical Amplitude axis, by clicking and dragging it in
various ways, to make the best use of the available display area.
It functions the same as the Amplitude axis of the Chart Window, controls are
identical and any change is applied to the Chart Window.
Setting the Range

The Range pop-up menu lets you select the input range, or sensitivity, of the
channel — the combined range of the PowerLab and Bio Amp. Changing the
range in the Bio Amp dialog is equivalent to changing it in the Chart window.
The default setting (if you have not loaded a settings file) is 20 mV, rather
than 10 V, and the ranges go down to 100 μV in eight steps.

28

PowerLab Owner’s Guide

Figure 2–7
The Bio Amp dialog for
Windows

Signal amplitude

Pause and Scroll buttons

Range pop-up
menu

Filtering
options

Amplitude axis

Click this to open the Units Conversion dialog

Amplitude axis

Signal amplitude

Figure 2–6
The Bio Amp dialog for
Macintosh

Range pop-up
menu

Filtering
options

Open the Units
Conversion dialog

Pause/Scroll button

Compression
buttons

Filtering

Each of the Bio Amps in the PowerLab has low-pass, high-pass and mainsfilter circuitry that can be adjusted to suit the recording. Note: the settings for
one filter type may restrict the possible settings for the other.
High-pass filtering
The High pass pop-up menu gives the choice of two high-pass filters: 0.5 and
Chapter 2 Setting Up

29

10 Hz. The high-pass filter allows high frequencies in the signal to pass, and
removes frequency components below the filter frequency (including any DC
signal). These filters are useful for removing slowly moving baselines, such as
motion or respiration artifacts, particularly in ECG (EKG) recordings.

Low-pass filtering
The Low pass pop-up menu gives the choice of eight low-pass filters: 10, 20,
50, 100, 200 and 500 Hz, and 1 and 2 kHz. These filters are useful for
removing high-frequency signals, such as noise.
DC Restore
Click DC Restore to reduce the time constant of the high-pass filter so that
the filter can rapidly adjust to an altered baseline value.
Mains filter
The mains filter allows you to remove interference at the mains frequency
(typically 50 or 60 Hz). Select Mains filter to turn on the mains filter. This is
an adaptive filter and should only be used when the signal to mains noise
ratio is less than 36 dB, that is the mains noise amplitude is greater than 1/64
of the signal amplitude. More details on the mains filter can be found in the
LabChart Help Center.
Anti-alias
Select Anti-alias to apply a sample rate-dependent low-pass filter that prevents
aliasing artifacts. The input signal is sampled and digitized at 100 kHz. The
AD converter is preceded by an analog anti-aliasing (low-pass) filter of fixed
cutoff frequency (Ý49 kHz). When LabChart or Scope samples at 100 kHz,
the converted samples are passed on unchanged. At all other LabChart or
Scope sampling rates, an additional (digital) filter is optionally applied to the
AD converter's 100 kHz output stream. This is a decimating FIR filter whose
cutoff frequency is set to the Nyquist value: half the LabChart or Scope
sampling frequency. It thus acts as an automatic anti-aliasing filter, providing
optimum noise rejection in the recorded data. Attenuation in the stop band is
at least 40 dB. Note that anti-aliasing is disabled at sampling rates below 100
Hz so as to prevent the delay that otherwise occurs as samples pass through
the FIR filters.
The anti-aliasing filter characteristics are chosen to give the fastest step
response without overshoot (corresponding to an analog Bessel filter). Such a
response is suited to most types of physiological recordings. In the frequency
domain, the filter response starts to roll off well below the cutoff frequency. In
certain (relatively uncommon) types of measurement, a maximally flat
response is desirable; this can be obtained by turning anti-aliasing off.

30

PowerLab Owner’s Guide

Inverting the Signal

Selecting Invert allows you to invert the signal on the screen. It provides a
simple way to change the polarity of the recorded signal without having to
swap the connections to the recording electrodes.
Units

Clicking Units… opens the Units Conversion dialog, letting you specify the
units for a channel, and, using waveform measurements, to calibrate the
channel. A waveform in the data display area of the Bio Amp dialog is
transferred to the data display area of the Units Conversion dialog. (Use the
Pause button to capture a specific signal.) The units conversion only applies to
subsequently recorded signals, so it is more limited than choosing units
conversion directly from the Channel Function pop-up menu, as it does not
allow conversion of individual blocks of data.

Chapter 2 Setting Up

31

32

PowerLab Owner’s Guide

A P P E N D I X

A

A

Technical
Aspects

This appendix describes some of the important technical aspects of your
PowerLab, to give some insight into how they work. You do not need to know
the material here to use your PowerLab. It is likely to be of special interest to
the technically minded, indicating what the PowerLab can and cannot do, and
its suitability for particular purposes. You should not use it as a service
manual: user modification of the PowerLab voids your rights under warranty.

Appendix A Technical Aspects

33

How it Works
The PowerLab is essentially a smart peripheral device specifically designed to
perform the various functions needed for data acquisition, signal
conditioning, and pre-processing. It contains its own microprocessor,
memory and specialized analog amplifiers for signal conditioning.
All sampling, output and communication functions are controlled by an
internal microprocessor. This microprocessor has access to 16 MB of internal
dynamic RAM for data storage and buffering. The PowerLab uses USB 2.0 to
communicate with the computer, if the computer is USB 2.0 compliant. This
provides data transfer rates of up to 480 Mbits per second. If the computer
only supports USB 1.1 the data transfer rate will be slower.
The 15T and 2/26 PowerLabs have two analog inputs, whereas the 26T and
4/26 PowerLabs have four analog inputs. They are used to record external
signals prior to digitizing. Each of these input amplifiers connects to a
separate 16-bit ADC (analog-to-digital converter) that samples at 100 000
samples per second. The sampling process is handled independently of the
processor core through a sampling control engine using direct memory
access. The CPU assembles groups of samples into blocks and then transmits
them to the computer, where the software receives, records and displays the
data.
Two 16-bit DACs (digital-to-analog converter) are used to provide an analog
output or stimulation capability through the analog outputs of the PowerLab
(marked ‘Output’ on the front panel). The DACs can produce constant DC
voltage levels or waveforms under software control. Stimulation frequency is
completely independent of the analog input sampling rate. The output of the
DACs is fed through a programmable attenuation network to produce
different output ranges. The signal is then split into a positive and negative
output through buffer amplifiers. The outputs are capable of driving up to
20 mA into a load.
The PowerLab uses an IEC60601-1 (medically) compliant switching power
supply. This provides a universal input that handles all common international
voltage supplies and frequencies without the need to change voltage ranges.
This power supply is also internally protected in the case of a problem. It is
important to note that the PowerLab has a limited amount of power available
for external devices. Because of these power limitations, you should not use
the PowerLab as a power source for external devices other than those
produced by ADInstruments.

34

PowerLab Owner’s Guide

The Analog Inputs
SCaution
Applying more than ±15 V to
the input can damage the
input circuits.

PowerLab input amplifiers have been designed with a considerable amount of
computer-controlled gain (up to × 2000). Thus it is possible to record a variety
of signals without any external pre-amplification. Each analog input is a
separate DC amplifier with programmable gain able to be set independently
(the gain is set through the software range control). The PowerLab inputs can
be set by the software to be either single-ended or differential. In the
differential setting, the amplifier measures the difference between the positive
and negative inputs, irrespective of ground.
It is important to note that the PowerLab grounds the inputs to amplifiers not
in use. It also grounds each amplifier and measures the DC offset voltage
when the gain is changed. In this way, the software corrects for any DC drift
or offset in the circuits that may develop over time or between readings.
Input impedance is one megohm (1 MΩ). Each analog input is fitted with a
fixed 25 kHz low-pass filter.
On the 15T and /26 model PowerLabs, the impedance between the earthing
stud (ground connection) and the input connector grounds is close to zero.

The Analog Outputs
SWarning
Analog outputs are not to
be used for connection to
human subjects.

Figure A–1
The analog output stage,
set up for a differential
stimulus

The analog outputs provide computer-controlled variable outputs (±10þV)
that can be used with the LabChart and Scope applications either directly as a
stimulator, or to control peripheral devices. All stimulation voltage is
generated by the PowerLab via the output sockets on the front of the
PowerLab (marked Output + and –), giving positive, negative, differential, or
independent stimuli, depending on the sockets used and the software settings.
+10 V
From DAC

+
Ground

–

– 10 V
+10 V
– 10 V

By default, the outputs are used for complementary (differential) stimulation,
where Output + is positive and Output – is negative. When Output + is used,
a positive stimulus voltage (set up in LabChart or Scope) gives a positive
voltage output, and a negative voltage a negative one. When Output – is used,
the voltage outputs are inverted. When both output sockets are used, the
stimulus is the difference between the voltages at the positive and negative
outputs: you could generate up to a 20-volt pulse, given a ±10 V range setting.

Appendix A Technical Aspects

35

The External Trigger
The external trigger input (not on PowerLab 15T) is marked ‘Trigger’ on the
front panel and provides a digital input for synchronizing sampling with
external devices. It allows either a voltage level or a contact closure to trigger
recording. Note that for either mode the trigger signal must be present for at
least 3 μs to register as an event. When a trigger event occurs, the indicator
light will glow yellow.
When set up through software to use a voltage level, above which a rising edge
trigger event is registered, the external trigger level is 2 V. The external trigger
input is off for input voltages between –12 V and the external trigger level,
and on between that level and +12 V. The input will be overloaded if the
voltage is outside the range –12 V to +12 V. The trigger input is isolated when
set up for a voltage level.
The equivalent circuit of the external trigger has two diode protection.In the
external contact closure mode, the trigger input will respond to a direct short
between the center pin and outer ring of the BNC. This can be achieved with
an external relay contact, a manual push-button or a microswitch. The trigger
input is not electrically isolated when set up for contact closure.
+3.3 V

Figure A–2
The equivalent circuit of
the external trigger input,
when set up for a voltage
level

Trigger
(BNC connector)

1.2k ohm
resistor

47k ohm
resistor

100 pF

The equivalent circuit for the external closure trigger is shown in Figure A–3.
The BNC input connects to a TTL circuit via a resistor circuit and has twodiode protection.
Figure A–3
The equivalent circuit of
the external trigger input,
when set up for contact
closure

+3.3 V
Trigger
(BNC connector)

1.2k ohm
resistor

47k ohm
resistor

100 pF

36

PowerLab Owner’s Guide

In order for the external trigger to work, a voltage must be applied between
the outer ring and the inner pin of the connector. Applying a voltage just to
the center pin may not work.

Bio Amp Input (Inputs 3 & 4)
The PowerLab 15T and 26T have one common connector for two Bio Amp
channels, marked Bio Amp 3 & 4. These two independently controllable,
electrically isolated, biological amplifiers are suitable for a range of basic
physiological measurements. The two Bio Amp inputs are internally
configured to use channels 3 and 4 of the PowerLab. The Bio Amps have a
common six-pin connector with a shared ground.
Each amplifier consists of an electrically isolated, AC coupled, differential
amplifier with programmable gain able to be set independently (the gain is set
through the software range control: the less the range, the more the gain). The
gain is controlled by optically isolated digital control signals from the nonisolated section. The signal is then applied to an isolation amplifier which
provides electrical isolation of the input stage from the supply.
The non-isolated stage consists of a series of filters and amplifiers. The first
part of the stage is a high-pass filter designed to remove any DC components
from the signal and the isolated stage. This is followed by amplification and an
active notch filter. The notch can be turned on or off under software control
as needed. The frequency of the notch filter is automatically set to either 50 or
60 Hz to match the frequency of the connected power supply.
The low-pass filter is an eighth-order, switched-capacitance, Bessel-type filter,
with a software-selectable range of frequencies. The output of the biological
amplifier is then passed to the standard PowerLab input amplifier circuit. On
the PowerLab 26T an amplifier connected to the output of the biological
amplifier is used to provide an audio output facility that can be used with
headphones or powered speakers.
Figure A–4
Block diagram for one of
the two Bio Amplifiers
(Input 3 & 4)

Auto
restore
Isolation amplifier
Signal
Input

+

Output

HPF

-

Audio Output (26T only)
Reference
Gain control

IGND
IGND

HPF control

IGND

Isolation barrier

Appendix A Technical Aspects

37

The Isolated Stimulator Output
The Isolated Stimulator output provides a software-controlled, isolated,
constant-current pulse stimulator that can be used for any general purpose
stimulation.
The output stage consists of a high-voltage, constant-current source that can
produce pulses of variable duration and amplitude under full software control.
The current source can deliver pulses up to 20 mA at 100 V maximum
compliance levels; its amplitude is controlled by optically isolated digital
control signals from the non-isolated section. The output to the subject is
through high-isolation optical couplers.
Software and hardware safety features limit the energy delivered by the pulses
to within international safety standards. The pulse duration of the stimulator
can be set from 50 μs to 200 μs, and the pulse frequency can be adjusted
between 1 pulse per minute and 20 pulses per second on Windows (and
between 2 pulse per minute and 20 pulses per second on Macintosh).
The Isolated Stimulator Pulse indicator is an LED that is used to indicate the
current status of the Stimulator. It will flash green forevery stimulus pulse, and
may seem to glow green constantly at higher stimulus frequencies. The OOC
(out-of-compliance) indicator is a yellow LED. When lit, it indicates that the
output is overloaded or out of compliance (compliance is the ability to supply
voltage to meet the required current). This means that the impedance of the
tissue being stimulated is too high, or there is a poor electrical connection
(possibly due to electrode drying), and that the Isolated Stimulator can no
longer supply constant current stimulation. If this should happen, try
reducing the output current amplitude, and check all connections.

Figure A–5
Block diagram of the
Isolated Stimulator

Transformer
driver

Stimulator
Power
Supply

Stimulus Output
Stimulus Isolator
switch

Current setting DAC
Constant current source

Stimulate
Stimulator pulse
safety control

INDICATORS
Out of Compliance

Stimulate

Isolation amplifier

38

PowerLab Owner’s Guide

PowerLab Accuracy
The PowerLab was calibrated at the factory to an accuracy of better than 0.1%.
Some ‘zero drift’ or ‘gain drift’ can occur with time. This can affect the
accuracy of measurements, especially at the highest input gains. The unit can
be recalibrated, but in most circumstances this is not necessary in its lifetime.
Calibration facilities. It is good practice to calibrate a measuring system from
the transducer to the output. After applying two known values to a transducer
(say at 20% and 80% of full scale) and recording the signal, you can use the
units conversion feature of ADInstruments software to convert and display
transducer readings in the appropriate units. This will compensate for any
minor inaccuracies in amplifier gain and transducer calibration.
DC drift compensation. When a recording is started manually or by
triggering, or the gain is changed, the input signal to the amplifier is grounded
and any DC, due to amplifier drift of temperature and age, is measured. The
measured voltage is removed from the input signal through software
correction, in a process transparent to the user.

Connectors
This section of the appendix contains ‘pinout’ and electrical details of some of
the connectors fitted to the PowerLab. You should read it carefully before
attempting to connect cables other than those supplied with the unit to the
PowerLab. Using cables that are wired incorrectly can cause internal damage
to the PowerLab and will void your rights under warranty. For further
information or advice please contact your nearest ADInstruments
representative.

Digital Input and Output
The digital input port and digital output port are 15-pin connectors situated
on the back panel of the PowerLab 26T. The eight digital input lines respond
to 3.3 V logic signals with a threshold of 1.2 V, and have a 10 kΩ input
impedance. The eight digital output lines can turn on and off, or signal to, up
to eight external TTL devices. The digital output lines are capable of driving
8 mA each.
The inputs and outputs conform to industry standard HCMOS structures
powered with a 5 V supply. The digital input and output ports both have a pin
which can supply power to solid-state relays or similar devices. Total

Appendix A Technical Aspects

39

Digital output

OUT 1
OUT 2
OUT 3
OUT 4
OUT 5
OUT 6
OUT 7
OUT 8

Digital input

IN 1
IN 2
IN 3
IN 4
IN 5
IN 6
IN 7
IN 8

8
15

5V

1
9
5V

8
15
GROUND

1
9

GROUND

Figure A–6
The pin assignments for
the digital input and output
connectors

aggregate current from these pins is 200 mA continuous at 5 V. The digital
input signals should not exceed 5 V.
Note that any cables connected to either the digital input or output must be
less than 3 m in length in order to maintain EMC compliance.

I2C Expansion Connector
The I2C port on the back panel of the PowerLab 2/26, 4/26 and 26T provides
expansion support for ADInstruments front-ends. This port provides both
power and control signals for these front-ends. The I2C bus has a daisy-chain
structure that allows simple connection of additional front-ends to the system.
A PowerLab can have as many front-ends connected to it as it has appropriate
connections. You should not attempt to run other external devices from the
I2C port: it is designed for use only with ADInstruments front-ends. Only
50 mA maximum current can be provided through this bus, so it should not
be used for third-party devices as they may draw more current.
Front-end power

5
9

40

I2C control signals

DGND
UNREG–15 V
UNREG+7 V
UNREG+15 V
SCL
DSC
SDA
DSD
INT

Figure A–7
The pin assignments for the
I2C connector

1
6

PowerLab Owner’s Guide

Figure A–8
The pin assignments for the
analog inputs

[8] SCL

[7] Analog ground

[6] Input (+) ref.

[3] Input (+)

[1] Positive 5 V

[5] SDA

[4] Negative 5 V

[2] Input (–)

[*] Digital ground (metal ring)

Input Connectors
The input connectors (Figure A–8) of the PowerLab 15T, 2/26, 4/26 and 26T
are 8-pin DIN connectors. They allow the connection of ADInstruments pods
— small, low-cost signal conditioners for specific tasks, for use with
precalibrated transducers. Transducers designed for direct connection can be
provided with power and control through the connectors.
The PowerLab 2/26 and 4/26 also have BNC input connectors as well as the 8pin DIN connectors.
Note that with the PowerLab 26T:
•

•
Figure A–9
The USB icon and port

ADInstruments front-ends, such as the ML221 Bridge Amp, can be used
with inputs 1 and 2 (but not inputs 3 or 4) by connecting them with the
DIN-to-BNC adaptor.
When an ADInstruments pod is connected to either input 3 or 4, the
corresponding Bio Amp input is turned off.

USB Connection
PowerLabs have a USB 2.0 port, and connect to a computer with USB ports or
a PCI USB card installed, allowing high data transfer rates to USB 2.0compliant computers (slower transfer to USB 1.1-compliant computers).
The signal must be transmitted in a certain time; in practical terms this means
cables between any USB devices, including hubs, must be no more than
5 meters (16 feet) in length, and with hubs in the chain, devices must be no
more than 30 meters (98 feet) from the computer. For proper use and reliable
results, the PowerLab needs a high-speed connection. Your PowerLab is
supplied with a high-speed USB cable. If you replace the USB cable, buy a
high-speed cable (fully shielded, twisted-pair and standard USB connections:

Appendix A Technical Aspects

41

a narrow rectangular plug at one end and a square plug with a bevelled top at
the other).
When devices that transfer a lot of information, such as scanners and video
cameras, are connected to the same USB tree and are used at the same time as
a PowerLab, sampling rates may be limited considerably (in LabChart) or
delay times between sweeps may increase (in Scope). Newer computers (both
PC and Macintosh) usually have several independent USB ports. Using these,
rather than a hub, to connect multiple devices will avoid them competing for
capacity (bandwidth).
You can safely turn on or off, or disconnect or reconnect, a USB-connected
PowerLab while the computer remains on, as long as the application program
(LabChart or Scope) is off when you do it.

Earthing and Ground Loop Noise
The prime function of earthing is safety, that is, protection against fatal
electrocution. Safety concerns should always override concerns about signal
quality. Secondary functions of earthing are to provide a reference potential
for the electrical equipment and to mitigate against interference.
The earthing (grounding) stud provided on the back panel of the PowerLab is
a potential equalization post and is compatible with the DIN 42801 standard.
It is directly connected to the earth pin of the power socket and the PowerLab
chassis. The earthing stud can be used where other electronic equipment is
connected to the PowerLab, and where conductive shields are used to reduce
radiative electrical pick-up. Connection to the stud provides a common earth
for all linked devices and shields, to reduce ground-loops.
The earthing stud can also be used where a suitable ground connection is not
provided with the mains supply by connecting the stud to an earthed metal
infra-structure, such as a metal stake driven into the ground, or metal water
piping. This may also be required in laboratories where safety standards
require additional grounding protection when equipment is connected to
human subjects. Always observe the relevant safety standards and
instructions.
Note that magnetically-induced interference in the recorded signal can be
reduced by minimizing the loop area of signal cables, for example by twisting
them together, or by moving power supplies away from sensitive equipment.
This can reduce the inductive pick-up of mains frequency fields. Please
consult a good text for further discussion of noise reduction.

42

PowerLab Owner’s Guide

A P P E N D I X

B

B

Specifications

Analog Inputs

Number of input channels:

15T:

2 DIN

2/26:

2 DIN and BNC

4/26:

4 DIN and BNC

26T:

4 DIN

Configuration:

DIN are single-ended or differential
BNC are single-ended

Amplification ranges:

Range

Resolution

±10 V
±5 V
±2 V
±1 V
±500 mV
±200 mV
±100 mV
±50 mV
±20 mV

313 μV
156 μV
62 μV
31 μV
15 μV
6 μV
3 μV
1.5 μV
625 nV

Maximum input over-voltage:

±15 V

Input impedance:

15T:

1 MΩ || 150 pF

2/26:

1 MΩ || 150 pF

26T:

1 MΩ || 150 pF (Inputs 1 & 2)
1 MΩ || 200 pF (Inputs 3 & 4)

4/26:

1 MΩ || 150 pF (Inputs 1 & 2)
1 MΩ || 200 pF (Inputs 3 & 4)

Appendix B Specifications

43

Input coupling:

DC or 0.15 Hz (software selectable)

Maximum bandwidth:

25 kHz

DC drift:

Software corrected

CMRR:

> 105 dB at a gain of 100

Interchannel crosstalk:

> 90 dB

Signal-noise ratio:

> 100 dB (±10V range)

Accuracy error:

Less than 0.2 %

Non-linearity (max):

0.1 %

Filters - Low pass:

1, 2, 5, 10, 20, 50, 100, 200, 500, 1000,
2000 Hz and Anti-alias

- Notch:

Mains

Pod Connectors (DIN)

General features:

Combined power, I2C and single-ended or
differential analog input signals on one
connector, support SmartPod transducers,
etc.

Supply voltage:

±5 V regulated

Maximum current:

50 mA per pod connector

Communications:

2-wire I2C

Signal input:

Positive and negative analog inputs and
analog return

Connector type:

8-pin DIN with metal surrounds

Sampling

44

ADC configuration

Each channel has its own ADC
(2/26 and 15T have 2; 4/26 and 26T have 4)

ADC resolution:

24-bits

ADC linearity:

±0.0006 % FSR (INL)

Maximum sampling rates:

100 000 samples/s per channel (concurrent);
400 000 samples/s (aggregate)

Available sampling rates:

100 000 samples/s down to 10 min/sample

PowerLab Owner’s Guide

Bio Amp Input – Inputs 3 & 4 (PowerLab 15T & 26T)

Number of channels:

2

Input configuration:

Differential with common isolated ground

Amplification ranges:

Range

Resolution

±20 mV
±10 mV
±5 mV
±2 mV
±1 mV
±500 μV
±200 μV
±100 μV

625 nV
313 nV
156 nV
62 nV
31 nV
15 nV
6 nV
3 nV

Gain accuracy:

1%

Non-linearity:

1%

Noise:

< 1 μVrms (0.5 – 2 kHz)

Maximum input over-voltage:

±5 V

Input leakage current:

< 4 μArms @ 120 V, 60 Hz
< 4 μArms @ 240 V, 50 Hz

DC blocking:

±0.3 V

Baseline restoration:

Automatic or user-controlled

Input impedance:

100 MΩ to isolated ground (~500 pF per
lead) using supplied Bio Amp subject cable
and lead wires

Safety:

IEC60601-1 and CSA approval

Isolation rating:

4000 V ACrms (1 minute)

IMRR:

130 dB

CMRR:

110 dB

Filters - High pass:
- Low pass
- Notch

Single pole 0.5 Hz and 10 Hz
10, 20, 50, 100, 200, 500, 1000, 2000 Hz
Mains

Audio output (26T only):

Stereo output socket supplying an analog
audio signal from both bio amp channels.
Suitable for earphones, headphones and

Appendix B Specifications

45

most externally powered speakers.
Output is 300 mV at full scale.
Output Amplifier

Output configuration:

2 Outputs – Complementary

Output resolution:

16-bit

Maximum output current:

20 mA

Accuracy error:

Less than 0.2 %

Linearity error:

±0.5 LSB (INL) (typical)
±0.5 LSB (DNL) (typical)

Output ranges:

±10 V
±5 V
±2 V
±1 V
±500 mV
±200 mV

Output slew rate:

2.3 V/μs

Settling time (G=1, 10 V step):

5 μs

Output impedance:

0.001 Ω

Isolated Stimulator Output (PowerLab 15T & 26T)

46

Output configuration:

Constant-current stimulator with hardware
limited repetition rate

Isolation rating:

4000 Vrms to ground as per IEC60601-1
2000 Vrms to Bio Amp inputs

Pulse duration:

50 – 200 μs (software selectable)

Compliance voltage:

100–110 V typical

Output current:

0 – 20 mA in 0.1 mA steps (software
selectable)

Pulse rate:

Software selectable, but hardware-limited to
a maximum of 1000 Hz and 200 μs for
safety.

Safety indicators:

Green and yellow indicators. Green flash
indicates delivery of a valid stimulus.
Concurrent green and yellow flash indicates
an out-of-compliance condition.
PowerLab Owner’s Guide

Safety switch:

Provides physical disconnection of the
stimulator from the subject.

External Trigger (not on PowerLab 15T)

Trigger mode:

TTL level or contact closure, software
selectable

Trigger threshold:

+1.3 V (rising edge), +1.1 V (falling edge)

Hysteresis:

0.3 V

Input load:

HCMOS

Maximum input over-voltage:

±12 V

Minimum event time:

3 μs

Expansion Ports (not on PowerLab 15T)

I2C expansion port:

Power and control bus for front-end units.
Supports a number of front-ends equal to
the number of PowerLab analog inputs.
Interface communications rate of up to
10 Kbits/s.

Digital ports (26T only)
- Output:

8 independent lines, TTL output level
(8 mA maximum load per line)

- Input:

8 independent lines, TTL input level,
threshold 1.2 V, 10 kΩ input impedance, 5V
maximum

Microprocessor and Data Communication

CPU:

Digital Signal Processor – Freescale
DSP56858

RAM:

4 Mbit SRAM

ROM:

1 Mbit Flash ROM

Data communication:

Hi-speed USB 2.0 (max of 480 Mb/s
transfer) compatible with USB 1.1 hosts.

Physical Configuration

Dimensions (h × w × d):

65 mm × 200 mm × 250 mm
(2.56" × 7.9" × 9.8")

Weight:

1.8 kg

Appendix B Specifications

47

Operating Requirements

Operating voltage range:

95–264 V AC, 47–63 Hz

Rated power:

25 VA

Operating conditions:

5–35 °C, 0–90 % humidity (noncondensing)

ADInstruments reserves the right to alter these specifications at any time.

Electromagnetic Compatibility
The ML818 PowerLab 15T, ML826 PowerLab 2/26, ML846 PowerLab 4/26
and ML856 PowerLab 26T (the devices) have been tested to comply with IEC
60601-1-2:2004 (AS/NZS 3200.1.2) including IEC 61000-3-2, IEC 61000-3-3,
IEC 61000-4-2, IEC 61000-4-3, IEC 61000-4-4, IEC 61000-4-5, IEC 61000-46, IEC 61000-4-8, IEC 61000-4-11 and CISPR 11 Group1 Class A.
Emissions
•

The devices are suitable for use in all establishments other than domestic and
those directly connected to the public low-voltage power supply network that
supplies buildings used for domestic purposes. There may be potential difficulties
in ensuring electromagnetic compatibility in other environments, due to
conducted as well as radiated disturbances.

Immunity

See Table B–1 p. 49.
•

•
•

48

Mains power quality should be that of a typical commercial or hospital
environment. If the user of the devices requires continued operation during power
mains interruptions, it is recommended that the devices be powered from an
uninterruptible power supply or a battery.
Power frequency magnetic fields should be at levels characteristic of a typical
location in a typical commercial or hospital environment.
Floors should be wood, concrete or ceramic tile. If floors are covered with
synthetic material, the relative humidity should be at least 30%.

PowerLab Owner’s Guide

Table B–1
Immunity test compliance

Immunity test

IEC 60601 test level

Compliance level

Electromagnetic
environment
guidance

Conducted RF
IEC 61000-4-6

3 Vrms
150 kHz to 80 MHz

3V

Recommended separation distance
(see Table B–2 p. 50)

Radiated RF
IEC 61000-4-3

3 V/m
80 MHz to 2.5 GHz

3 V/m

Recommended separation distance
(see Table B–2 p. 50)

Electrostatic discharge
IEC61000-4-2

±6 kV contact
±8 kV air

±4 kV contact
±8 kV air

Floors should be wood,
concrete or ceramic tile.
If floors are covered with
synthetic material, the
relative humidity should
be at least 30%.

±2 kV for power supply
lines
±1 kV for input/output
lines

Mains power quality
should be that of a typical commercial or hospital environment.

Electrical fast tran- ±2 kV for power supply
sient/burst
lines
IEC61000-4-4
±1 kV for input/output
lines
Surge
IEC 61000-4-5

±1 kV differential mode ±1 kV differential mode Mains power quality
±2 kV common-mode ±2 kV common-mode should be that of a typical commercial or hospital environment.

Voltage dips, short
interruptions and
voltage variations
on power supply
input lines
IEC61000-4-11

<5% UT (>95 % dip in
UT) for 0.5 cycle

Mains power quality
should be that of a typical commercial or hospi40% UT (60% dip in UT) 40% UT (60% dip in UT) tal environment. If the
for 5 cycles
for 5 cycles
user of the devices
require continued opera70% UT (30% dip in UT) 70% UT (30% dip in UT) tion during power mains
for 25 cycles
for 25 cycles
interruptions, it is recommended that the devices
<5% UT (>95% dip in
be powered from an
UT) for 5 sec
uninterruptible power
supply or a battery.

Power frequency 3 A/m
(50/60Hz) magnetic
field
IEC 61000-4-8

Appendix B Specifications

<5% UT (>95% dip in
UT) for 0.5 cycle

3 A/m

Power frequency magnetic fields should be at
levels characteristic of a
typical location in a typical commercial or hospital environment.

49

Separation Distances
•
•

•

The devices are intended for use in an electromagnetic environment in which
radiated RF disturbances are controlled.
Portable and mobile RF communications equipment should be used no closer to
any part of the devices, including cables, than the recommended separation
distance in the table below.
Field strengths from fixed RF transmitters, as determined by an electromagnetic
site survey, should be less than the compliance level in each frequency range.

Table B–2
Separation distances

50

Separation distance
Rated maximum output
power of transmitter, P

150 kHz to 800 MHz

800 Mhz to 2.5 GHz

d = 1.17ÐP

d = 2.33ÐP

0.01 W

0.1 m

0.2 m

0.1 W

0.4 m

0.7 m

1W

1.2 m

2.3 m

10 W

3.7 m

7.4 m

100 W

11.7 m

23.4 m

PowerLab Owner’s Guide

Glossary

C

AC coupling. A filter option. When AC coupling is chosen, a 0.1 Hz highpass filter before the first amplification stage removes DC and frequency
components below 0.1 Hz. This removes slowly changing baselines.
ADC (analog-to-digital converter). A device that converts analog
information into some corresponding digital voltage or current.
amplitude. The maximum vertical distance of a periodic wave from the zero
or mean position about which the wave oscillates.
analog. Varying smoothly and continuously over a range. An analog signal
varies continuously over time, rather than changing in discrete steps.
analog input. This refers to the connectors on the front of the PowerLab
marked ‘Input’. These inputs are designed to accept up to ±10 volts. Inputs can
be either single-sided or differential (the latter only in the case of the pod
connectors).
analog output. This refers to the connectors on the front of the PowerLab
marked ‘Output’. The analog output provides a software-controlled variable
output (±10 V) that can be used with applications either directly as a
stimulator, or to control peripheral devices. Not for use with human subjects.
analysis. When the PowerLab is not physically connected to the computer,
then ADInstruments software can be used to analyze and manipulate existing
files if the analysis option is chosen.
BNC (bayonet nut connector). A type of cable or connector; a BNC-to-BNC
cable connects two BNC connectors.
bridge transducer. A type of transducer using a Wheatstone bridge circuit. In
its basic form, the bridge consists of four two-terminal elements (usually
strain gauges) connected to form a quadrilateral. An excitation source is

Glossary

51

connected across one diagonal, and the transducer output is taken across the
other.
bus. A data-carrying electrical pathway (cables and connectors).
connector. A plug, socket, jack or port used to connect one electronic device
to another (via a cable): a PowerLab to a computer, say.
CPU (central processing unit). A hardware device that performs logical and
arithmetical operations on data as specified in the instructions: the heart of
most computers.
DAC (digital-to-analog converter). A device that converts digital
information into some corresponding analog voltage or current.
DC offset. The amount of DC (direct current) voltage present at the output of
an amplifier when zero voltage is applied to the input; or the amount of DC
voltage present in a transducer in its equilibrium state.
differential input. Input using both positive and negative inputs on a
PowerLab. The recorded signal is the difference between the positive and
negative input voltages: if both were fed exactly the same signal, zero would
result. Can reduce the noise from long leads.
DIN (Deutsche Industrie Norm). A type of cable or connector; there are
various sorts with different numbers of pins.
envelope form. The overall shape of a signal, outlined by the minimum and
maximum recorded values. Often used to display quickly changing signals.
excitation voltage. The voltage supplied to a bridge circuit from which the
transducer output signal is derived. Manipulating the transducer changes the
measurement elements of the bridge circuit, producing a change in its output
voltage.
external trigger. The input connector on the front of the PowerLab marked
‘Trigger’. This lets you start recording from an external source. The trigger
level (the voltage needed to have an effect) depends on the hardware and
cannot be changed. Recording can also be triggered by contact closure, if this
is set up in the software.
filter. An electronic device or a program that alters data in accordance with
specific criteria. Filters in hardware and software can be used to reduce or to
eliminate electronic noise or drift from data readings.
frequency. The number of complete cycles per second of a waveform.
Frequency is usually expressed in hertz: Hz (cycles per second), kilohertz:

52

PowerLab Owner’s Guide

kHz (thousands of cycles per second), or megahertz: MHz (millions of cycles
per second).
frequency response. The bandwidth in which a circuit passes a signal without
too much attenuation. A low-pass filter’s frequency response is the frequency
where the output voltage becomes 0.707 (1/Ð2) of the input voltage or has
been attenuated by 3 decibels. If a low-pass filter has a frequency response of
200 Hz, say, then the signal is effectively unattenuated up to 150 Hz, and is
0.707 of the original value at 200 Hz.
front-end. An ancillary device that extends PowerLab capabilities, providing
additional signal conditioning and features for specialized work. Front-ends
are recognized automatically by the PowerLab system and seamlessly
integrated into its applications, operating under full software control.
gain. The amount of amplification of a signal.
half-bridge transducer. A bridge transducer only using half of the full-bridge
circuit. It consists of two elements of equal value with an excitation voltage
applied across them. The output of the transducer is taken at the junction of
the two elements.
hertz (Hz). The unit of frequency of vibration or oscillation, defined as the
number of cycles per second. For example, the minimum sampling rate for a
human ECG experiment should be 400 Hz (400 samples/s).
high-pass filter (HPF). A filter that passes high-frequency signals, but filters
low ones, by blocking DC voltages and attenuating frequencies below a certain
value (the cut-off, or –3 dB, frequency).
I2C (‘eye-squared-sea’). This connection is used by the PowerLab to control
front-ends. It provides power and communication using a
4-wire serial bus (two wires for standard I2C and two control lines).
IEC. International Electrotechnical Commission.
LabChart. An ADInstruments software application that emulates a multichannel chart recorder, with other powerful options. (Macintosh and
Windows versions differ slightly.)
LabTutor. An ADInstruments application for teaching physiology that
integrates the experiment protocol, real-time data acquisition, analysis and
reporting as interactive pages in the Internet Explorer browser.
low-pass filter (LPF). A filter that passes low-frequency signals and DC
voltages, but filters high ones, attenuating frequencies above a certain value
(the cut-off, or –3 dB, frequency).

Glossary

53

MacLab. An earlier name for the PowerLab, before it became cross-platform.
PCI (peripheral component interconnect). A protocol for connecting
peripheral devices (such as USB cards) to computers and so on.
pod connector. A special 8-pin DIN connector on some PowerLabs giving
differential or single-sided connections for analog inputs. Pods can connect to
them, and they can also provide power and control for some types of
transducers.
pods. Small, low-cost units that connect to the PowerLab’s pod connectors.
They give alternatives to front-ends for specific tasks, for use with
precalibrated transducers and so on.
port. A socket where you plug in a cable for connection to a network or a
peripheral device. Also, any connection for transferring data, for instance
between the CPU and main memory.
PowerLab. The PowerLab hardware unit is a self-contained data acquisition
hardware unit that connects to a Windows or Macintosh computer. When
used in conjunction with programs such as LabTutor, LabChart and Scope, it
functions as a versatile laboratory instrument.
PowerLab system. The system consists of a hardware unit and applications
software (and possibly ancillary devices). It provides a multi-purpose data
recording, display, and analysis environment for experimental data.
range. In LabChart and Scope, the range is the greatest positive and negative
voltage that can be displayed, usually from ±5 mV to ±10 V, in 11 steps.
(Range is inversely proportional to gain, the extent of amplification.)
Scope. An ADInstruments software application that emulates a two-channel
storage oscilloscope, with added powerful options. (Macintosh and Windows
versions are very similar.)
serial. A connection protocol for sending information sequentially, one bit at
a time, over a single wire.
transducer. A physical device that converts a mechanical, thermal or
electrical stimulus into a proportional electrical output. For example, there are
common transducers to measure force, displacement, temperature, pressure,
and similar parameters.
trigger. A signal, such as a voltage pulse, used to determine when sampling
will begin. Sampling can be made to begin when the trigger level is reached,
after it, or even prior to it. See also external trigger.

54

PowerLab Owner’s Guide

TTL (transistor-transistor logic). A family of integrated circuits (ICs) with
bipolar circuit logic, used in computers and related devices.
TTL is also a standard for interconnecting such ICs, defining the voltages
used to represent logical zeroes and ones (binary 0 and 1).
USB. Universal Serial Bus.
waveform. The shape of a wave; a graph of a wave’s amplitude over time.

Glossary

55

56

PowerLab Owner’s Guide

Index

A

D

ADC (analog-to-digital converter) 34
ADInstruments contacts 12
analog input 15, 35
analog output 15, 34, 35
analog-to-digital converter 34
anti-aliasing 30
audio connector 18

DAC (digital-to-analog converter) 34
DC drift 35, 39
DC restore 30
digital input 18, 39
digital output 18, 39
digital-to-analog converter 34

B

earthing 42
electromagnetic compatibility 48–50
error patterns 22
external trigger 13, 36

back panel 17–19
Bio Amp
cable 19–20
inputs 16, 37
software 28–31

C
calibration 39
checking the PowerLab 12
compliance 16, 38
connections
audio 18
digital 18
front-ends 15, 41
ground 19
I2C 18, 40
pod 15, 41
power 19
PowerLab to computer 23, 41–42
safe, to humans 15
USB 18, 23, 41
contact addresses 12

E

F
filtering 29
front panel 13–16
front-ends 20

G
ground connection 19
ground loops 42

H
high-pass filter 30

I
Isolated Stimulator
output 16, 38
software 24–27
Isolated Stimulator panel 27
I2C connector 18, 40

L
LabChart 23
Index

57

low-pass filter 30

M
mains filter 30
marker 27

P
pod connection 15, 41
pods 20
Power indicator 13, 22
power switch 19
PowerLab
accuracy 39
back panel 17–19
calibration 39
connectors 39–42
front panel 13–16
input amplifiers 35
power supply 34
safety 15
self-test 22

S
safety 15
Safety Notes 5–10
safety switch 16
Scope 24
self-test 22
Status indicator 13, 22
stimulator controls 24–27
Stimulator Pulse indicator 16, 38
Stimulator software 24–27
storage 10

T
technical specifications 43–48
transducers 20
trigger 13
Trigger indicator 13

U
USB
connection 18, 23, 41
high-speed cables 41
port 42
user modification voids warranty 33

58

PowerLab Owner’s Guide
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