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Variable DC power supply

Discussion in 'Electronic Basics' started by Stumpy, Aug 31, 2006.

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  1. Stumpy

    Stumpy Guest

    I'm planning on testing a house light dimmer switch to provide <120 Vac for
    a bridge rectifier circuit with a one choke and two capacitor filter.

    I presume that the dimmer will put out an attenuated sine wave so I can dial
    up 0 - ~60 Vdc.

    Is this feasible?

    Also, the choke I bought at Radio Shack (273-102) has one end of the wire
    wrapped around the core soldered to one lead of the choke. Does it matter
    which way this points? Towards the PS or towards the load?
     
  2. No. You need a fan speed controller - light dimmers are usually asymetrical.
    Doesn't matter
     
  3. Stumpy

    Stumpy Guest

    Also not linear. I did a test with a dimmer switch direct to the bridge
    circuit. Got 50 Vdc at the output - no load - in the minimum position.
    Turned the dimmer up to 1/2 of full rotation, got 60 Vdc. Turned it up a
    hair more, heard a slight buzzing from the dimmer and then the 1000 uH
    capacitor blew.

    Took awhile to get the capacitor oil off my desk. I guess the 50 volt
    rating was serious. I'm still interested to try the dimmer, but should have
    added a step-down transformer.
     
  4. We ran low voltage lamps via fan speed controls - or look for a symmetrical
    design to build. If you can find one of the old GE SCR Handbooks it had some
    good design info. Running a lot of DC through your transformer does nasty
    things.
     
  5. jasen

    jasen Guest

    not usually.
     
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