This circuit is from an Electronics World of 1968. The transistors are of the time and the power is supplied with a voltage of 40 V. The circuit is high fidelity.
This circuit was found in a 1958’s publication. It uses germanium transistor, availble that time....
This circuit is suggested by Texas Instruments in his Optoelectronics Sourcebook. The transistors...
This circuit is from a 1968 documentation using one of the first integrated circuits available at the...