This two-tube circuit, one being a double, was found in Radio Electronics magazine from July 1958. The distance to the microphone depends on noise and losses. The cable must be shielded.
Using a pair of CK722s, this booster step of a few milliwatts of power was obtained in a 1960...
We found this circuit in a Radio Shack documentation from 1977. The circuit serves for a link of...
Other operational amplifiers can be used on this unit gain amplifier. The circuit is from the 1993...