Found in an RF Design from the 90's this circuit is intended for crystals of less than 1 MHz. Transistors are types of general use today.
This infrared emitter (pulsating) can be used with several other alarm and remote-control circuits on...
Signals of up to a few tens of kilohertz can be generated by this circuit found in a European...
This amplifier was found in a technical documentation from the 1970s. The circuit uses 2N2218...