This circuit with two operating modes was found in the September 1989 issue of Radio Electronics magazine. Other operational amplifiers can be used. The power supply must be dual.
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...