Multichannel Systems SC8x8BC - Manual (Page 3)

Multi Channel Systems
MCS GmbH
Aspenhaustrasse 21
72770 Reutlingen
Germany Fon +49-7121-9 09 25- 0
Fax +49-7121-9 09 25-11
[email protected]
www.multichannelsystems.com
© 2011 Multi Channel Systems MCS GmbH
Product information is subject to change
without notice.
SC8x8BC
Warning: The device may only be used together with the MPA8I from Multi Channel Systems
MCS GmbH, and only for the specified purpose. Damage of the device and even fatal injuries
can result from improper use.
!
Use and Operation
The SC8x8BC is a Signal Collector with blanking circuit for up to eight MPA8I preamplifiers. The 8x8 input
channels are collected, and then connected to the following amplifier via 68-pin MCS high grade cable.
The SC8x8BC includes a 0.08 Hz high pass filter for removing DC offsets.
An internal power supply with 5 V stabilizes the power for all eight MPA8Is.
The additional ground on the front panel ensures perfect grounding.
The SC8x8BC features a blanking circuit. Without a SC8x8BC, when you apply a stimulus input to your
filter amplifier, the amplifier gets saturated and needs to recover.
The recovering time depends on the filter amplifier type. It is roughly the time constant of the high
pass filter multiplied by ten. During this time, the data output is distorted. With the blanking circuit,
the voltage outputs are held constant during the time when the blanking input is active. Thus,
the stimulus artefacts does not pass through the box, and the following filter amplifier does not get
saturated. When the blanking signal has stopped, the channel output follows the input signal again.
Blanking is triggered by a TTL signal. If you use a STG (stimulus generator) for stimulation, you can set
up the trigger in MC_Stimulus and apply it with a STG via the Sync Out connector. Make sure to start
the blanking TTL signal shortly before the stimulus, and stop it shortly after the stimulus to remove the
complete stimulus artefact.
After the trigger event, the output channels are reconnected to the input channels.
This event is accompanied by three minor artifact signals:
1. Small switch artifact, which is caused by the switch itself (less than 20 mV).
2. Possible DC residual (depending on the electrodes and DC balance of the stimulus signal).
3. Possible switch feedback (cross talk between TTL blanking pulse and the ground line).
The time constant of the device, that is, the time it needs to reach the current voltage level again,
is 22 ms.
 
TTL Signal
Input signal (stimulus)
Output signal
t
DC Residual