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Finally, 12v @ 5amps !

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  • Finally, 12v @ 5amps !

    After trawling through the net 4 ages i finally found this psu:
    the 12v part of the circuit is rated at 5amps, and the psu would also work with the engine off.

    Heres a direct link to the schematic:

    Before attempting to build the 12v part of this circuit, I just have a few quick questions, as the website can be unclear at times
    1) Instead of using a transformer, should an inductor be used instead (im only using this circuit for 12v)?
    2) How many henries... (the lm2577 datasheet is quite vauge about this)? would a 100uF inductor suffice?
    3) What should be heatsinked.... the semiconductors probably need heatsinking, but what about the transistors?
    4) If so, how the hell would u heatsink a transistor? The one i seen is the shape of a boilied sweet, kinda like this -> <O>
    5) I can't work out what version lm2577 he has used?... I guess that its the lm2577-15 as he says on the webpage that the voltage is stepped up to 15v first.
    He might have used the lm2577-adj though, as there are resistors on the circuit, and i can't work out what they could do, exept adjust the output voltage.

    Btw, i've ordered almost all the parts, but i thought i`d better get these things resolved before i start soldering.

    Also, one last thing.... would i be able to increase the output to, say, 10amps easily?
    I know this sounds silly, but i have an lcd that runs off 12v, and it needs 3amps. Is just a case of hooking up another transistor for the 12v part of the circuit?
    If i cant, i'll use a ldo 7812 based circuit for it.

    My Setup