This 50% active cycle TTL clock generates signals from 4 to 20 Hz. Its power must be supplied with 5 V and other frequencies can be generated with capacitor replacement.
This different audio amplifier was found in a 90's Electronic Design. The circuit uses components...
Using components from the 70s, this circuit can be implemented with modern equivalent components....
This circuit was found in documentation from the 1980s. The circuit can be designed based on...