This crystal oscillator is indicated for the calibration of IF steps of common radio receivers. The transistor admits equivalent as 2N2222 or BF494. The circuit is from an old American publication.
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...