This circuit comes from a Gernsback Publications of the 90s. The circuit uses a general-purpose transistor as a sensor. The power supply must be symmetrical.
This circuit makes use of an unusual component today, a LASCR. It is a light-activated SCR. The...
This circuit was found in a 1976 documentation. It can be used with old tape recording mechanisms for...
The FET of this circuit of a 1971 publication may be the BF245. The circuit serves as a voltage...