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12vdc to 5vdc Answered

Can anyone help me, I need a way to convert 12vdc from a vehicle battery to 5vdc for an application that I am working on. I need to do this in a way that it will not fail quickly, and also on the smallest form factor that I can.

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Big Bwana (author)2008-11-06

or a 5 volt Zener Diode, if you don't have much current demand. (( few mA area )) And if you need efficiency or more power than a 78L05 can deliver, a small switched mode supply, they can easily handle 2 amps output with out need for a heat sink ((( And before you think a switched mode supply, sounds like lots of work. it's often cheaper to just buy an automotive lighter socket to USB adapter at a dollar store and use the gut's most will deliver 1 to 2 amps output and accept 8 to 24 volts input, nice if your boosting a battery and you forget to unhook items .. and the one I just picked up, I couldn't make it for a buck )))

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11010010110 (author)Big Bwana2008-11-08

i saw somewhere a switching power supply built as drop-in replacement for 7805 its kinda 20x20 mm circuit board with SMT components and 3 hard wires. you stick the entire thing into the main circuit as if its 7805

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guyfrom7up (author)Big Bwana2008-11-07

usually there's just a 7805 inside of those

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Big Bwana (author)guyfrom7up2008-11-07

All the one's I've opened up are a simple switched mode supply with smt resistors, caps, a 8 pin dip and an inductor, no 7805 or heat sink and they output 2 amps at 5 volts with out much problem and very little heat..... the last one I played with was over 95% efficient and it didn't even get warm (( honestly the resistor limiting the current going to the L.E.D. put out more heat then the whole power supply, the wire cutters quickly fixed that problem ))

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Gjdj3 (author)NachoMahma2008-11-07

Google is always the answer! haha.

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guyfrom7up (author)2008-11-05

get a 7805 chip from radioshack

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janders223 (author)guyfrom7up2008-11-05

So I only need the 7805 and nothing else?

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11010010110 (author)janders2232008-11-06

fast capacitor on the in (and out if you use it to power electronics) most non-electrolytic capacitors are fast. connect a 1uF+ fast capacitor in parallel with 100uF+ electrolytic one to combine spped with high capacity (its not perfect but a good working cheap solution) for currents below 100mA you may use 78L05 - a compact 7805 heatsink if needed

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NachoMahma (author)janders2232008-11-05

. Probably need a heatsink, but you can use the car (eg, firewall, dash brace).

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