This circuit was found in an old American magazine for radio amateurs. The circuit is based on a very high voltage tube of the time.
This circuit excites an LED, which will flash at a frequency adjusted by the trimpot. The other...
This circuit, found in a publication from the 1970s, produces a 1 Hz sinusoidal signal....
In this circuit, the output voltage is Vxx plus the zener voltage. The circuit is from the SGS...