This circuit responds to frequencies from 100 Hz to 3 MHz. We find it in a 90s Radio Electronics. Transistors are general purpose types.
This circuit is from a Radio Electronics from March 1970. The crystal depends on the frequency at which...
This circuit detects magnetic fields through a sensor coil, providing a signal in its function. The...
Described in an article that taught how to assemble the complete intercom in Radio Electronics magazine...