Found in a 1980s American documentation, this circuit operates with 5 V signals requiring 55 cycles of 500 Hz for tone recognition. The circuit can be adapted to operate with other frequencies.
The amplifier shown in the figure was obtained from the Anlog Devices linear integrated circuits...
If the reader still uses silk screen printing tables this is an interesting circuit found in a 1994...
This circuit monitors the output of a stereo amplifier, checking the balance and balance between...