Power supply for Valve type Paraset

To save the schematic RIGHT CLICK within the graphic and use "SAVE PICTURE AS"

Geoff G3YVF was given the task by G4VSZ to design a power supply for the value version of the paraset but it needed to run off a 12v DC battery.

2N3773 devices are much more robust than the originally selected 2N3055.

CAUTION danger of multimeter destruction

The design of some transformers may cause very large spikes to be produced at the A.C. output of the transformer. So when testing DO NOT connect a digital type multimeter directly across the transformer A.C. output in an attempt to measure the A.C. output voltage. Failure to observe this might result in your multimeter's destruction.

It is considered that the best way assess the output of the transformer is :-

to measure the D.C. (NOT THE A.C.) output after the rectifier and smoothing part of the circuit, no spikes there and after all we are interested in the D.C voltage NOT the A.C. voltage!!