Photodetector signal conditioning box

This device allows the connection of the photodetector to an oscilloscope or multimeter. For this purpose the photoelectric current which is proportional to the number of incident photons needs to be converted into a voltage. This is done by the simple however very effectively. The device is driven by a 9 V battery which lasts almost one year under regular operation. The impedance of the output can be adjusted from 50 Ohms to 100 k. The “OFF” position still provides via an 1 M Ohm shunt a signal with a very high sensitivity which sometimes is useful. For fast signals the lower shunt resistors are used. Rise times of 2 ns can be measured in the 50 and 100 position.