This amplifier was found in a tube equipment manual from 1947. The high-fidelity circuit has pentode tubes at the output and a source with transformer.
We found this circuit in a 1965 publication by General Electric. The zener is 8.2 V x 1 W and the...
This circuit was obtained in an Electronic Engineering of the 90s. The operational amplifiers and...
This circuit is suggested by Texas Instruments in his Optoelectronics Sourcebook. The transistors...