This amplifier with gain control was obtained in a documentation from Signetics of the 80's. Transistors are of power and operational amplifiers are not common nowadays.
We found this amplifier for automotive use in the Philips integrated circuit manual from 1990. The...
This interesting circuit records a few seconds of audio signals, reproducing them in a small...
Settings like this can be found at various points on this site. The trigger door can be a 4093...