Transformerless 220VAC-12VDC PSU

826

17:33:50

Inspired by techplanet's circuit, this PSU is a slim version of his already fantastic circuit. Current source is standard PAL format (220VAC 50Hz).Output is 12VDC. The values are all calculated to keep the output current between 12.1 and 19.9 volts, the best result i could achieve by tuning the NPN-based regulator. Amperage tuning is done by changing resistance of the first resistor. Actually it's set on 100mA.
Thanks to hurz for useful tips!

published 11 years ago

tpfohl

11 years ago

I think you will get shocked on the output if you don't galvanically separate the circuit but i still like it.

hurz

11 years ago

Your AC source is a mix of 220VDCrms and 220VAC. Correct should be DC=0 and AC suppose to be in your country 311VAC. And yes, its transformerless, but if you have ground in your country its dangarous, and the 1k resistor >>45Watt is bigger than a little transformer. So its bigger, its not safe, its inefficient.

Jack23247

11 years ago

Updated. Thanks for your comments!

Jack23247

11 years ago

Voltages in my country are 2-phases 220VAC 50Hz and 3-phases 380VAC. By fixing the input i was able to reduce significantly the resistance of the first resistor, and the circuu

Jack23247

11 years ago

*circuit now works better. Sorry for triple post, I'm starting to hate my phone.

hurz

11 years ago

In EC you configure the peak voltage. 220Vpeak is equivalent to 155VDC! You have to configure 311Vpeak to get 220VAC. And 1Ohm is also not a good idea. measure the current!

Jack23247

11 years ago

It should be better now, current is significantly reduced. I also put 311V peak.

hurz

11 years ago

The current is going upto 600mA in peak and looks also like a rectangle. Suppose this is a DC current of about 250mA, the power disipation at resistor is calculated by P=I^2*R = 0.25^2 * 500 = 31Watt. This power goes directly into heat!

Jack23247

11 years ago

Efficiency could actually be a tough problem, but i'm not planning to build it, so if it could virtually work it's already a great goal for me...

hurz

11 years ago

Ok, but also keep an eye on the cap at input, in case you plug into powerline while the voltage gets a maximum your circuit will draw extremly high current, just for a short while but a heavy spike. You could test this plugin behavior by use of a 220V rectangle.

faceblast

11 years ago

probably illegal to plug this in. You should probably be fairly safe though, because the 500 ohm resistor will most likely explode before it can emit enough heat to set fire to anything. The transistor will shoot through and the resulting load should burn your fuses out.