CED 1902 User guide

1902 application guide
A guide to setting up CED 1902 amplifiers
03/9/2012
Cambridge Electronic Design Ltd.

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Notes
The 1902
amplifier is a
versatile unit
suitable for a wide
range of research
applications that
take recordings
from surface or
needle electrodes.
The 1902 is a single channel modular unit that can be combined
into ‘stacks’ to give multiple amplifier channels. All settings for the
1902 are controlled directly from within Spike2 and Signal, or
from a standalone amplifier control program if neither of the
above are being used. This guide is intended to help you setup a
1902 for recording.
Requirements: CED 1902 amplifier
Optional: Spike2 or Signal for Windows, Power1401 or
Micro1401 laboratory interface, Electrode adaptor box, USB to
serial adaptor.
The CED 1902 is sold as a research instrument and not as
a medical device within the meaning of the EC Medical
Device Directive.

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Contents
Page
What type of 1902 do I need?
•1902 options by application
•How many channels?
3-4
3
4
Connecting to the Isolated electrodes input
•CED1902-11 Electrode adaptor boxes
•CED1902-10 Active Head Stage
•Wiring your own Isolated electrode input connection
4-5
4
5
5
Transducer and Trigger inputs
5
Software Installation
•Spike2 and Signal
•Signal conditioner support
•Check for available COM ports
6-7
6
6
7
Hardware configuration
8
1902 amplifier setup
•Control of the 1902
•The 1902 control panel
•Setting Gain and Offset
•Filters
•Triggering the Input clamp
9
10
11
12
13
14-15
Standalone control of 1902
16-17
Troubleshooting
17

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What type of 1902 do I need?
1902 options by application
The following table shows the 1902 options that would typically be required
for a range of research applications. This table is intended for use as a guide
only. If you have other requirements or wish to check the suitability of the
1902 for your specific application, you should contact CED directly.
* Including Force, acceleration, temperature, strain and displacement transducers. Standard gain is x1 – x100,000
**Includes Blood pressure or other invasive transducers that are connected to a subject
#Input clamp is required if recording fast responses or from close to the site of stimulation
##ECG front end with 5 lead switching under software control
The isolated input port of the 1902 will give the best results for
most recordings due to its superior gain and low-noise.
Application
Non-Isolated Isolated
Standard gain
(x100 –
x100,000)
Optional gain
(x1000 –
x1,000,000)
Optional Input
clamp#
Optional
ECG front
end
##
Transducer
(non-invasive)*
*
Transducer
(invasive)**
MEP recording
(TMS)#
EMG
ECG##
EEG
Evoked
potentials

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How many channels?
Each 1902 is a single channel modular unit, but they can be combined into
stacks to give multiple channels or supplied as dual or quad channel variants
with optional rack-mounting. Multiple stacks, dual or quad channel units can
then be ‘daisy-chained’ together to give the number of channels required.
Connecting to the Isolated electrode input
When recording from electrodes attached to a subject, the electrodes must be
connected to the isolated electrode input port of the 1902. There are a
number of connection options available, depending on the number of channels
and the electrode types being used.
Electrode adaptor boxes
These are available in 2, 4, 8 or 16 channel variants with bipolar or common
reference options and provide direct connection to the Electrode input sockets
of multiple 1902 channels from one compact device. The electrode connectors
on the adaptor boxes accept 1.5mm touch-proof electrodes. Adaptors to
connect 2mm electrodes can also be supplied if necessary.

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Active head stage
The Active Head Stage also provides direct connection to the 1902 electrode
input sockets and is available in a 2 or 4 channel version for use with
concentric or wire needle electrodes. It provides differential amplification with
switchable gains of x1, x3 and x10.
Wiring your own Isolated electrode input connection
If you are not using one of the CED1902-11 electrode adaptor boxes or the
Active Head Stage, you can wire your own connectors using the supplied DIN
plug included with the 1902. The Isolated electrode input is a 6-pin DIN
socket which should be wired according to the pin descriptions in the 1902
user manual.
The 1902 can supply an excitation voltage suitable for invasive transducers
and other devices that require connection between a human subject and the
Isolated electrode input. Contact CED for further details.
Transducer and Trigger inputs
Wiring your own connection for the Non-isolated transducer input
The non-isolated transducer input uses an 8-pin DIN socket and supplies
excitation voltages suitable for driving non-invasive transducers. The wiring
information can be found in the 1902 user manual.
Wiring your own connection for the Trigger inputs
The Trigger inputs use a 4-pin mini-DIN socket. The wiring information can
be found in the 1902 user manual.
Subjects must NOT be connected to the transducer input or Trigger ports.

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Software installation
Spike2 and Signal
Install the software from the supplied CD. After setting the installation
directory, your name and organisation and selecting Compact, Custom or
Typical setup, the following page will appear.
Signal conditioner support
This option is used to install software
support for a signal conditioner along
with Spike2 or Signal. Select CED
1902 signal conditioner and click Next.
Information on setting up a 1902
amplifier for recording can be found in
the 1902 amplifier setup section.
The CED 1902 amplifier is
controlled via a COM port
(RS232). Many desktop PC's will
have at least one COM port
available (usually COM1). For
laptops and PCs without an
available COM port, a USB to serial
adaptor can be used instead. This
should be plugged in to an available
USB port before continuing.

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If you know the COM port you want to use, select it here and click Next. If
you are not yet sure which port you want to use you can check for available
COM ports as described below, or select COM1 at this stage and then simply
change the 1902 COM port in the Edit menu Preferences > Conditioner
section in Spike2 or Signal later on.
Check for available COM ports
All available COM ports are listed in the
Windows Device Manager. The quickest way to
open the Device Manager on any version of
Windows is to use the Windows key + R
keyboard shortcut to open the Run command,
enter devmgmt.msc in the dialog and Click OK.
You can also open the Run command from the
Start menu in Windows XP. In Windows 7 you
can access the Device Manager from the
Control Panel in the Start menu or open the
Run command from the All Programs >
Accessories folder in the Start menu.
In the list of hardware devices should be an entry for Ports (COM & LPT).
Click on this to show the available ports. You can edit the COM number
assigned to a port for most devices by double-clicking on the entry. Click on
the Port Settings tab and then the Advanced... button. You can set the COM
port number from a drop-down list.
Once the 1902 conditoner support option has been selected you can continue
with the installation. There are a number of other options, some specific to
Spike2 or Signal, that you can select as required.

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Hardware configuration
The diagram below shows the control line from the computer as either a
direct serial port connection OR via a USB to serial converter. This connection
is made to the back of the 1902 amplifier unit or to the bottom-most 1902
in a stack of multiple amplifiers.
For recording from surface electrodes on humans the isolated ‘Electrode’ input
of the 1902 must be used. Output of the amplified/filtered signal is then
produced at the ‘Amp Out’ BNC connector.

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1902 amplifier setup
With mains power off, connect the power cable and included RS232 serial
cable to the rear of the 1902. Connect the power cable to a power outlet and
the RS232 cable to an available COM port on the host PC or to the USB-
serial adaptor that you connected to a USB port on the host computer during
software installation. Switch on the mains outlet to power up the 1902. Once
the green Power LED is lit, the 1902 is ready for use.
If you are using Spike2 or Signal and the 1902 conditioner support option
was selected during the installation, complete control over the 1902 amplifier
settings is provided via a control panel which can be used to adjust amplifier
gain and offset, modify filter settings and enable triggering and clamp
duration if the 1902 has been fitted with the input clamp option. If powered
up and connected to the PC, the 1902 will be detected when Spike and
Signal are first run.
By default, the control software expects each 1902 channel to be connected
to the corresponding ADC port number on the 1401 interface using BNC
cables, which you should connect now. This example uses a single 1902,
channel 0, which is connected to ADC 0.
Don’t want to use the ADC port on the 1401 that matches the 1902 channel
number by default? For instance you may already be using ADC Inputs 0-2
but want to connect a 1902, which is set to channel 0, to ADC Input 3. To
do this you need to change the 1902 channel number to match the ADC
Input using the rotary switch on the rear panel of each 1902 channel.