RF or even switching transistors like the 2N2222 can be used in this circuit. The capacitors are ceramic and the frequency is determined by the crystal.
This transmitter generates modulated infrared radiation and can be used as the basis for a remote...
This different audio amplifier was found in a 90's Electronic Design. The circuit uses components...
This oscillator generates a sinusoidal tone of 1750 Hz determined by the twin-T. The circuit can be...