This circuit was found in a Popular Electronics from the 90s. The counter circuit is not common today. The circuit can be programmed for hourly intervals, according to the values of R4 and C2.
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...