12V to 3V Convertor

This is an simple and cheap circuit to convert voltage from 12V to 3V.In fact this is a basic regulator circuit.The output voltage determined by

Vout = Vzener – Vbe

Vzener is zener voltage output.
Vbe is saturate voltage when transistor on (about 0.6V)

Fig 1. 12V to 3V convertor

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