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  1. #1
    Join Date
    Apr 2010
    Posts
    486

    Power supply question

    Need small amounts of 12 volt and 24 volt DC on the mill rehab. Used the original 18 volt CT transformer with a pair of monster bridges, no idea what they are, but the mill had a ton of them built in, and a pair of 4200 mfd 50 volt caps. (Trying to get maximum use out of the original factory supplied components.)

    Then we knocked one of the input terminals off the transformer and destroyed it. Duh.....

    Local surplus dealer gave me a monster 24 volt CT transformer ( 0.500 KVA ). Hooked it up with just 2 diodes in series with the transformer, and the same caps as filters.

    Now we've got about 36 vdc and 19 vdc, which is a bit higher than I'd like.

    Happen to have a couple of three tab voltage regulators, one 12 v and one 24 bolts which should arrive in a couple of days. <http://www.mpja.com/prodinfo.asp?number=0361+RG> I've never used a three tab regulator before, and my googling didn't find a good tutorial.

    Is the three tab regulator the best way to get 12 and 24 out of this setup? Can anyone point me to a tutorial on three tabs?

    Thanks

    Tom

  2. #2
    Join Date
    May 2008
    Posts
    666
    This will depend how much currant you'll need.

    Just put heat sink on the regulator.


    Normally, TO-220 regulator pin out is:

    1 = in
    2 = GND
    3 = out

    You have to calculate Vin - Vout (36-24) = 12 volts.

    Power dissipation will be 12 volts X by the currant.

    Just google LM7812 or LM7824 for schematic

    Jeff
    Attached Thumbnails Attached Thumbnails 7812.gif  

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