CAMBRIDGE CED 1902 User guide

i
The CED 1902 Mk IV Owners Handbook
Copyright Cambridge Electronic Design Limited 2017
Neither the whole nor any part of the information contained in,
or the product described in, this guide may be adapted or
reproduced in any material form except with the prior written
approval of Cambridge Electronic Design Limited.
1st edition (1.0) October 1991
2nd edition (1.5) February 1992
3rd edition (2.0) March 1997
4th edition (2.1) September 1997
5th edition (3.0) May 2006
6th edition (3.1) May 2008
7th edition (3.2) July 2012
8th edition (3.3) August 2014
9th edition (3.4) May 2017
Published by:
Cambridge Electronic Design Limited
Technical Centre
139 Cambridge Road
Milton
Cambridge
CB24 6AZ
UK
Telephone: [phone]
USA & Canada Toll Free 1-800-345-7794
Web: www.ced.co.uk
Email: [e-mail]
Trademarks and Tradenames used in this guide are
acknowledged to be the Trademarks and Tradenames of their
respective Companies and Corporations.

Table of Contents
ii
Publishing information.................................................................i
Table of contents........................................................................ ii
Life support.................................................................................v
Potential for Radio/Television Interference (USA only)............v
Storage and operating environment...........................................vi
Protection...................................................................................vi
Typographic conventions......................................................... vii
Use of symbols......................................................................... vii
Introduction.................................................................................1
Checklist......................................................................................1
The Electrode Box ......................................................................2
The Active Head Stage ...............................................................3
Installing the 1902 software........................................................5
Confidence check – Try1902......................................................5
Machine control ..........................................................................7
Electrical isolation.......................................................................7
RFI approvals....................................................................7
Safety approvals................................................................7
Signal input to the 1902..............................................................8
1902 functional organization ....................................................10
The waveform conditioner..............................................10
The trigger generator......................................................10
Features seen by the user ..........................................................12
Preface
Installation
General
information

Table of Contents
iii
Physical construction................................................................13
Installations with multiple 1902s...................................13
Rack mount installations................................................13
Using a USB port .....................................................................13
Channel numbers and how to set them.....................................14
1902 communication configuration .........................................14
Cable connections.....................................................................16
Power..............................................................................16
RS232.............................................................................16
Signal cables...................................................................16
Electrode cables .............................................................17
Mating connectors....................................................................17
Firmware – the 1902 flash ROM..............................................18
Software supplied with the 1902.............................................. 20
The Stand-alone Control Panel ................................................20
The control panel with CED applications................................ 22
Running the 1902 from Spike2.................................................23
Running the 1902 from Signal.................................................24
Main amplifier..........................................................................25
Isolation pre-amplifier..............................................................26
Isolated input............................................................................27
Transducer input.......................................................................28
Bridge transducers..........................................................29
Single-ended transducers ............................................... 29
Trigger circuit...........................................................................30
Wiring switches..............................................................31
RS232 cable.............................................................................. 32
Power supply............................................................................33
The hardware
Application
software
Electrical
Specification

Table of contents
iv
Basic mode of operation ...........................................................34
Multiple independent channels.................................................35
Multi-channel configurations and the1902 input buffer...........36
1902 input clamp option ...........................................................41
Use of the notch filter ...............................................................43
Theory of electrical isolation....................................................44
Cleaning the 1902 .....................................................................46
Updating firmware....................................................................46
Calibration.................................................................................46
Opening the 1902......................................................................47
Try1902: the calibration utility.................................................48
Contacting CED........................................................................49
Servicing the 1902 ....................................................................50
The 1902 motherboard..............................................................51
Features of the motherboard .....................................................52
Circuit diagrams........................................................................52
Exchanging 1902 daughterboards.............................................53
Updating the EEPROM.............................................................54
The EEG daughterboard ...........................................................55
The ECG daughterboard ...........................................................56
The filter daughterboard ...........................................................57
Index..........................................................................................58
Important note...........................................................................61
EC Declaration of Conformity..................................................62
Details of
operation
Inside the 1902
Index
EC Declaration
of Conformity

Preface
v
CED products are not authorized for use as critical
components in life support systems without the
express written approval of the chairman of the board
of directors of CED.
Life support systems in this context are systems which support
or sustain life, and whose failure to perform, when properly
used in accordance with instructions for use provided, can be
reasonably expected to result in a significant injury to the user.
A critical component in this context is any component of a life
support system whose failure to perform can reasonably be
expected to cause the failure of the life support system, or to
affect its safety or effectiveness.
The 1902 generates and uses radio frequency energy and may
cause interference to radio and television reception. Your 1902
complies with the Specification in Subpart J of Part 15 of the
Federal Communications Commission rules for a Class B
computing device. These specifications provide reasonable
protection against such interference in a residential installation.
However there is no guarantee that interference will not occur
in a particular installation. If the 1902 does cause interference
to radio or television reception, which can be determined by
turning the 1902 off and on, you can try to eliminate the
interference problem by doing one or more of the following:
•Re-orient the receiving antenna
•Re-orient the position of the 1902 with respect to the
receiver
•Move the 1902 away from the receiver
•Plug the 1902 into a different outlet so that the 1902 and the
receiver are on different branch circuits
If necessary, consult CED or an experienced radio/television
technician for additional suggestions. You may find the
booklet, prepared by the Federal Communications Commission,
helpful: How to Identify and resolve Radio/TV Interference
Problems. This is available from the US Government Printing
Office, Washington DC 20402, Stock no. 004-000-00345-4.
To comply with FCC rules, Part 15 J Class B Computing
device, use only shielded interface cables.
Life support
Potential for
Radio/Television
Interference
(USA only)

Preface
vi
The storage and operating environment for a 1902 must not
exceed the temperature range 0°to +50°Celsius, in conditions
of non-condensing humidity which should not exceed 95%
saturation, in an atmospheric pressure range of 500 hPa to
1060 hPa. The 1902 complies with relevant EU and USA
requirements for electromagnetic interference. The 1902 is
suitable for continuous operation. The 1902 is not protected
against ingress of water or dust. There are no hazardous
voltages inside the 1902. The 1902 can be recycled; please
contact CED for further details.
The 1902 offers Class I protection against electric shock. To
maintain the safety standard, accessory equipment attached to
the 1902 must also comply with relevant safety requirements
such as IEC601-1 or the relevant IEC standard e.g. EN60601-1
configured to comply with EN60601-1-1:2000.
The ‘Common’ lead on a three-wire electrode cable provides a
return path for the input amplifier bias currents. UNDER NO
CIRCUMSTANCES should this lead or any other electrode
lead be connected to mains earth. This will negate the 1902’s
isolation provisions and expose subjects to the risk of fatal
shock.
The 1902 is not protected against flammable anaesthetic
mixtures. It must NOT be used in the presence of such
mixtures.
Storage and
operating
environment
Protection
Electrode
‘Common’ leads
Anaesthetic gases

Preface
vii
The following conventions apply to the text in this manual:
•Titles of manual sections, other manuals and other
publications are in italics
•Labels and identifiers appearing on the equipment described
in this manual are in Arial
•Menu items, buttons, and other contents of computer displays
are in Arial italics
•Text entered by keyboard is in Courier New. Names of
keys are enclosed in angular brackets, e.g. <esc>, <enter>
Where applied, the symbols below have the following
meanings:
This symbol is used on the CED-approved power supply, to
denote that the electrical isolation is to IEC Type B standard.
This symbol is used on the power supply to indicate the mains
input is for AC power only.
This symbol is used on the power supply to show that the
outputs are DC only.
The CED 1902 is subject to the EU WEEE regulations and may
be returned to CED Ltd. for recycling.
Observe precautions against electrostatic discharge.
Attention, consult accompanying documents.
Typographic
conventions
Use of symbols

Installation
1
This section will guide you through the installation of your
CED 1902 Mk IV isolated pre-amplifier. This involves loading
the operating software and running an initial confidence check.
The installation kit for your 1902 comprises:
•One or more 1902s, either free-standing or rack-mount
•A power block with attached DC power cable
•A power-block mains cable suitable for your country
•An RS232 cable to connect the 1902 to your computer
•A kit of accessories, including plugs to match the front-
panel connectors
•An installation disk to allow you to install and check out
your 1902
•CED Electrode or Head Stage Boxes (optional)
•This owners manual
The 1902 power block will run with no adjustment on any
mains voltage from 100 V to 240 V, 50 Hz - 60 Hz, drawing
1.3 A maximum. It has no switch, being controlled by plugging
in and switching on at the mains socket.
The 1902 itself has no DC
power switch. For
electrical isolation to be
complete, mains power
must be disconnected from
the power block.
Use only the cables
supplied by CED. They
have the metal shells and
screening braid that are
necessary to meet the
requirements for control of
electromagnetic inter-
ference. Others may not do
so.
Introduction
Checklist
The power block
The power block
Powerbox™ PMP55 shown
Cables

Installation
2
The CED1902-11 family comprises optional electrode adaptor
boxes that plug into the electrode input sockets of CED 1902
isolation amplifiers. There are four variants of the smaller box:
•CED1902-11-2 2 channel (bipolar)
•CED1902-11-2B 2 channel (bipolar or common-reference)
•CED1902-11-4 4 channel (bipolar)
•CED1902-11-4B 4 channel (bipolar or common-reference)
CED also manufactures two 16-channel electrode boxes:
•CED1902-11-16 16 channel (common-reference)
•CED1902-11-16B 16 channel (bipolar or common-reference)
The electrode boxes have
input connectors for up to
16 electrode pairs plus
common electrodes. The
connectors can be either
1.5mm or 2mm safety
(touch-proof) types. The
boxes are passive, i.e. they
do not amplify the signals.
The outputs are connected
to the electrode inputs of
CED 1902 isolation
amplifiers via shielded
cables. The boxes have two
or more Common input
connectors that are linked
together and to the
Common leads of all the
output cables. The interior
of the box is coated with
electro-conductive paint
which is electrically
connected to the screens of
the output cables.
The Electrode Box
The 1902 Electrode Box
2-channel model shown