This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the 80's, using a component of the era. Transistors are general purpose types.
This circuit was found in an 80's Radio Electronics. The circuit multiplies the frequency of a low...
This circuit can be interleaved between guitars and guitars to give the fuzz distortion effect. The...
A complete test for opto-couplers can be made using the circuit Bellow. The function generator...