We found this circuit in a documentation from the 70s. Semiconductors are from the era and can be replaced by modern equivalents.
With a touch of S1 this circuit keeps a small strand of nichrome warm enough to light a cigarette....
This Hartley telegraphy oscillator operates with the transmitter signal generating a tone in a...
This circuit turns on a lamp in the dusk and turn off in the down. Only incandescent lamps can be...