We found this circuit in an American 1980s documentation. The circuit uses a piezoelectric transducer unusual in our day. The transistor is general purpose type.
This overtone oscillator can generate signals up to 150 MHz. The crystal determines the frequency and...
The circuit shown by the figure below can produce signals in the range between 20 kHz and 30 kHz....
This circuit is used to convert audio signals from na amplifier into infrared modulated signals....