This circuit was found in a 73 magazine for radio amateurs from the 90s. The circuit uses high voltage transistors and the relay is high voltage as well.
From an old manual of unijunction transistors, this oscillator generates different tones when the...
A negative floating regulator capable of supplying an output voltage of -100 V with regulation of 20 mV for...
Found in a Hands On Electronics of the 80s, this circuit makes use of a gas sensor of the time....