This circuit was obtained in a 1975 documentation. The maximum frequency depends on the diodes and the FET. Type 1N34 diodes and a FET BF245 can be used for frequencies up to 100 MHz.
This circuit is for transducers (headphones or speakers) of 200 to 300 ohms. The frequency is...
This circuit uses only two transistors, the first being low noise, being indicated for dynamic...
Found in 1960's Radio Electronics, this circuit provides an audio tone that depends on the logic...