This is the circuit for the HM-10ª, an instrument sold by Heathkit. The circuit is from a Radio Electronics from May 1963. The indication is by an analog instrument.
Relays specially designed for operation in harsh environments of Phoenix Contact can be purchased...
In the figure we have a typical Wien Bridge oscillator with AGC. The negative waveform is sampled by...
We found this circuit in an old documentation, but the circuit is current due to the components it uses and...