R1 may be 10k and R2 100k. The transistor can be the BC548 and instead of the small lamp we can use a series LED with a 1k resistor. D1 is germanium and C1 is 10 nF. C2 can be 47 nF.
This charger is from an old publication of 1975. The PNP transistor can be the BC558 and the NPN...
The transistor in this circuit can be replaced with any general-purpose equivalent. The time...
This circuit, using a unijunction transistor (UJT), converts a voltage applied to the input in a...