This variable oscillator with power step for alarms was found in an American documentation from the 90's. The power transistor must be equipped with a heat sink.
I found this circuit in an old document from 1981. The circuit can be implemented today with the...
The circuit presented is a 10 MHz oscillator with crystal, which already has several splitters for...
This two-transistor amplifier stage was obtained from the Encyclopedia of Electronic Circuits...