This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent components. The transistors may be BC558 and the transformer is obtained from a disused transistor radio.
This circuit, obtained from ancient English documentation, produces a pulse every 24 hours when a 50...
This digital pulse counter offers an LED indication. Its maximum frequency is of the order of 5...
This circuit was found in an old RF documentation. The circuit cuts out the incoming sinusoidal...