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Thread: 0 - 5 vdc regulated power supply schematic

  1. #1
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    Default 0 - 5 vdc regulated power supply schematic

    Im looking to build a simple power supply, possibly using an LM317 .
    Does anyone have a schematic to build this power supply ?
    Im using it to run the analog / 0-5v signal on a laser, to do some bench testing.

    must be variable 0 - 5vdc
    the LM317 chip will do 1 amp, so current is no problem.
    input will be 120 vac.

    Thanks in Advance,
    Carlos
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  2. #2
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    Hi

    You can go here... a ton of information on their site..
    You may need to dig a bit to get your zero requirement...

    http://www.national.com/ds/LM/LM117.pdf#page=1

    Cheers

    Ray
    NZ

  3. #3
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    ok, thanks for the info Pitts,

    i guess ill just get a wall wart that is approx 7.5 - 9 volts, (input voltage need to be approx 2 volts higher, than the voltage output to be regulated)
    so, a 7.5 vdc wall wart, into the LM317 circuit, should do the trick,
    time to go shoppin.........
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  4. #4
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    Carlos, if you are only going to use the supply to drive the modulation lines on solid state lasers, then I don't think using a 317 is the best bet. See the schematic below, most parts should be available at your local radio shack, maybe. This way you're not adjusting the regulator, just adjusting the final potentiometer which is basically set as a voltage divider. And the 7805 keeps your max output to around 5VDC.

    edit-just a quick warning, any circuit you wire up, connect a voltmeter to the output first and make sure the output is what's expected!
    Attached Images Attached Images
    Last edited by DZ; 12-23-2009 at 20:19.

  5. #5
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    Hey thanks DZ, unfortunately i just finished the power supply , using the lm317t, with an adjustable pot, putting out 0 - 5.4 volts,
    do you think i shoud not use the one i allready built?

    also, what is the voltage out of that transformer, in the circuit you recommended ?

    Thanks,
    carlos
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  6. #6
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    the circuit you did will work fine, but best practice is not to vary LM317 output voltage by trimming the adjust pin with a pot but to have it fixed 5V and use a pot to divide the voltage as DZ did on his schematic

    just calculate resistor values for 5V instead of your adjust pot, replace it by them, and put the pot at the end of the circuit like on the schematic, and you're done!

  7. #7
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    Thanks guys! , ill try putting the pot at the output of the regulator instead...
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