In a message dated 3/8/00 5:21:18 PM EST, tom_mcgahee@SIGMAIS.COM writes:

<< The output of an opamp is connected via a 47 ohm resistor to the Anode of
 the first optoisolator LED. The cathode of the first optoisolator LED is
 connected
 in series to the Anode of the second optoisolator. The cathode of the second
 optoisolator LED is connected to ground.
  >>

Thanks Tom,

But I failed to see where the analog input signal is applied.

Paul