This board uses a simple trans-resistive circuit to measure the amplitude from the tape sensors. It includes a potentiometer in the gain stage for varying lighting conditions but we have yet to find a lighting condition that requires us to tweak it.

The other cluster on this board is the extremely simple circuitry that turns a switch output (short circuit / open circuit) into a logic level high and low.

Click here to view the sensor board schematic in a new window.