BioSemi.nl

Hi,

I am trying to verify the correct timing of trigger codes by coupling a photodiode (facing the stimulus delivery monitor) to one of the BIOSEMI external electrodes through a bucket of salty water. With this setup I could compare directly stimulus onset with trigger code timing. I am worried that I might exceed the maximum voltage that AD box can receive. Photodiode connected to oscilloscope generates about 100mV when dim stimulus is presented. I was thinking of starting with destilled water...? Please advise.

Best,

Marjan

Even if you would exceed the input range of the ActiveTwo (500 mV peak-to-peak), the system would just clip. With just a photodiode (apparently in photovoltaic mode), it will be impossible to cause any damage to the ActiveTwo.

Use high-quality Ag-AgCl electrodes to connect the photodiode to the water. Using copper wires in the water may cause pollution of the ActiveTwo electrodes (which may cause increased low frequency noise).

Alternatively, you may want to consider purchasing the BioSemi photosensor for direct connection to the Ergo input on the AD-box (seehttp://www.biosemi.com/accessoires.htm)

Best regards, Coen (BioSemi)