This circuit was found in a 1968s American. Transistors are of general purpose and the input is a rectangular signal of appropriate amplitude.
This circuit was found in 80's Popular Electronics. The circuit uses an infrared-sensitive phototransistor...
Supplied in a 2005 Linear Technology Application Manual, this circuit monitors the charge and...
We found this circuit in an American 1980s documentation. Transistors may be general purpose...