Multichannel Systems STG4004+STG4008 Manual - Manual (Page 63)

Synchronizing Events
59
You can start and stop the trigger manually at any time using the LED Start / Stop buttons.
Custom switch for "remote-controlling" of the STG
You can connect any device that produces TTL outputs to the Trigger In connector of the STG,
for example a switch. For example, you can use a trigger for remote controlling the STG if it is
not within reach during an experiment. It is also possible to set up advanced experiments where
stimulation depends on preceding activities of the studied object.
The following picture shows a suggested circuit diagram for a switch used for remote controlling.
The resistor and capacitor work as a low-pass filter on the TTL signal and are necessary to reduce
ringing of the signal.