We found this circuit in an old documentation, but it is still current. General purpose transistors can be used, and the SCR can be the TIC106. The bell is a transducer with an oscillator (buzzer).
This photometer is based on a Wheatstone bridge that must be balanced by the linear potentiometer P1. The...
This 1997 documentation circuit was originally created for use with Camcorder type video cameras....
This simple circuit tests both monophonic and other two-wire audio cables. The circuit is powered...