This tone control was obtained in a Signetics documentation of the 90s. The integrated circuit can be practically any operational amplifier. The power supply is symmetrical.
This Motorola circuit uses only one transistor. The circuit is from 1965 documentation. The...
This circuit uses a piezoelectric transducer to produce sounds like a buzzer. Frequency is...
This circuit was suggested by General Electric in a 1965 documentation. The circuit can be...