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 circuit, which can only be used with incandescent lamps, is adapted to the common wall...
Audio frequencies in the 300 Hz to 30 kHz range can be measured with this circuit. Transistors allow...
In the event of a short in the output, the relay disarms interrupting the supply. To reset this...