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.
This circuit was obtained in an Electronic Design from the 80's. It has the adjustment of the gain...
This circuit was obtained in a 1977 magazine, but it can still be easily assembled, as the...
This circuit uses only passive components and must be tuned to the operating range. The circuit is...