240 VAC to 12 VDC and -12 VDC WITHOUT Transformer

169

02:05:25

It uses the wall plug and 2 diodes, rectifying half wave, then stabilized with condensers and zener. The transistors are used to give to the zeners a constant current.

published 11 years ago

Mamish

11 years ago

Sure but you're limited to quite low power uses since it's only 5% efficient or less. I get the appeal of the "220V LED" type circuits but the EC community has put a huge amount of thought into such a niche circuit.

Mamish

11 years ago

For a better transformerless circuit it'd be cool to see some more switching supplies. Even some real life USB chargers can be unusually inefficient (ever use a samsung charger? They get VERY warm) so some innovation there would be cool.

jordi9

11 years ago

I needed a plus and minus voltage in dc, to feed a max038 wich supports at maximum 50mA per pin. With 2 regulators I stabilized the 5's V and have the 12V or 16V to amplify the 2Vpp output. If you change the values of the components you will have a more powerfull output. Also if you know other circuits to have the same specs, and more efficient, I'm all ears...!!!!

jordi9

11 years ago

I have made calculations and if you mesure the current througt the rectifying diode and assume it as constant, the efficiency of the circuit is 25%!!!! But, the current througt the rectifying diode only peaks twice per period, reducing the power consumption, that makes the circuit much more efficient around 65%!!!! It works more like a pulsing power source than a linear one..!!!!

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