This circuit with automatic gain control was found in the July 1988 issue of Radio Electronics magazine. The circuit is based on a transconductance operational amplifier.
We found this circuit in an old QST magazine. The circuit is powered according to the thermostatic relay...
This circuit was found in a 90s Popular Electronics. The components are from the era. R3 must be...
Found in a 1968 EEE, this circuit accepts frequencies from 1 to 1000 Hz and control voltages from 0.1 to...