This passive circuit was found in old American documentation. It can be added to any amplifier input since having losses of 20dB.
The input resistance of this circuit is 60k and the pass band from 20 to 20kHz. The circuit is...
This direct detection circuit was found in a 1986 documentation. The output is of low power, but...
This circuit was obtained from Popular Electronics of the 1990s. It makes use of a mercury switch that...