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Thread: Simple 2amp 12volt Regulator

  1. #1
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    Simple 2amp 12volt Regulator

    Hello there,

    while most probably already know about how simile these can be, nice images and parts required below

    useful for external power for modems, drives, or anything else with minimal power needs, with a 5volt similar model, would also power DVD drives, external HDD's.

    Parts list
    7812 IC
    2x 47uF 50Volt Caps
    2x 100ish Ohm Resistors
    2x Standard Brightness Green LEDs
    You'll also need a standard PCB, 5holes X 10holes

    Total construction size with my heatsink was 1/2inch X Inch X Inch
    1 LED for power in confirm
    1 LED for power out confirm


    1amp stable with no Heatsink
    1.5amp stable with Heatsink and 0.4v Drop
    2amp moderately stable Heatsink + Fan 0.5 - 0.7v Drop

    Next step, getting 5 - 10 amps

    Images Attached









  2. #2
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    Further Test Results

    This Regulator is able to power my JBL 4x100watt rms amp up to approximately 50% (depending on gain) of max volume, after 50% volume amps drawn exceeds what i am comfortable with (1.6amps)

    while this is in essence a meaningless test as no one in there right mind would use a regulator on a car amp, it was useful in showing how much this amaxingly small setup can do.


    ---
    pyr0

  3. #3
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    UPDATE:

    added a Power MOSFET in parallel to help increase amps out, thus far the largest load ive been able to find (not the units limit just the only thing i had around to plug in) is my portable car fridge that runs at ~3amp. The MOSFET is obviously resonsible for the 1+ amp increase in output

    have also added a permanent fan that uses 0.15amps of the regulated output

    New Images included



    An indicated 2.76amps which is whats expected for the 3amp car fridge



    Improved look of the unit, not as small but increased stability and output has made it somewhat expectable size increase. Also able to see the 2 LED's, foreground is the output LED, background, glow only is the input. Thought this would be a useful feature as it is yet to be fused, and helps in problem solving should this be installed.
    Unit sitting on top of the current porta-power, old motorcycle battery, first time its actually been useful.
    (also note; my sexy workbench :P)

  4. #4
    Variable Bitrate billmee's Avatar
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    Thanks for sharing.

    If you are looking for a larger load try a headlight.
    I used one to compare the efficiency of a dc-dc to an inverter.

  5. #5
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    this is with 3 headlights running off it, 6.12 amps stable and rather cool which surprised me, pushing for 10amps after i get some sleep

  6. #6
    Variable Bitrate Grrrmachine's Avatar
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    So can we have the schematic for the simple 12V 2A psu? This would be useful for those running lilliput screens, for example.

  7. #7
    Newbie smartass365's Avatar
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    What about the sag in output voltage when running off a fully / somewhat charged battery at about 1 amp load?

    Wouldn't it only work when the alternator's spinning?

    How about some sort of booster converter instead?
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  8. #8
    Newbie corvettecrazy's Avatar
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    Quote Originally Posted by smartass365 View Post
    What about the sag in output voltage when running off a fully / somewhat charged battery at about 1 amp load?

    Wouldn't it only work when the alternator's spinning?
    I was wondering this as well, since every voltage regulator that I have used requires a 1.5-2v drop/difference between input and output to work properly. Which would mean you would have to have the car running for it to work.

    It would be awesome if I was wrong, hence me asking about it.

  9. #9
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    That's correct. For the 7812, Vin(min) is officially 14.5v, though it'll operate down to 13.5v with a 2v drop (Vout = 11.5).

    Have you considered a boost-buck converter such as the Linear Technology LTC3780? It'll guarantee Vout at up to 20A for Vin = 4 to 36 volts.

  10. #10
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    I also made one just like it, but with two 7812 in parallell for more current.
    My PC died as soon as i turned the key off (below 11 volt) !

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