Found in a 1960s documentation, this circuit uses an operational amplifier from the time and a current diode, both of which are difficult to find today.
This project was found in a 1982 publication, using only two transistors. Signal injectors are...
This old 1 W audio amplifier transistor circuit is from a 1967 Japanese magazine. The transistors are...
This circuit was found in the December 1957 Radio Electronics magazine in the patent section. It...