This circuit was found in February 1976, Radio Electronics magazine. The circuit is quite sophisticated using a fast-acting (thermometric) sensor and analog indicator.
This circuit can operate with signals up to 60 MHz using the indicated operational. We found it in...
This circuit takes advantage of the noise generated at the reverse biased junction of a germanium...
Equivalent transistors can be used on this 80's circuit. Any general purpose PNP transistor can work...