This small audio amplifier uses an uncommon integrated circuit today. The circuit is from a documentation from the 70s and is indicated for portable receivers of the time.
This circuit was found in an American documentation from the 60's. The transistors are from the...
This oscillator is indicated for the adjustment of FI of FM radios, having its frequency...
This configuration triggers an external circuit or simply an LED for time given by R1 and C1 (T =...