This amplifier for the 10 m (30 MHz) band has a gain of 12 to 15 dB having been found in an American documentation. Other RF transistors can be used like 2N2222 or 2N2218.
Tone controls for audio applications can also be considered filters that must attenuate certain...
We found this basic circuit of a relaxation oscillator with unijunction transistor in a 1976...
This unusual unijunction transistor SCR firing circuit was found in a General Electric...