1. trainster

    trainster New Member

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    Any of you Electrical experts know how to take the 19v AC output on my power pack usually used for accessories, dim the output with a variable knob so the bulbs last longer, I use the DC on spare packs to dim lights but I would like to be able to do that with my 19v AC leads.
    Thank You :parghh:
     
    Last edited by a moderator: Mar 29, 2010
  2. brahamfireman

    brahamfireman TrainBoard Member

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    you could get complicated and put a transformer in there to drop it down to a lower voltage. or put a Resistor in one of the lines but the resistor will get pretty hot.
     
  3. Jack28

    Jack28 TrainBoard Member

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    Why not get a voltage regulator. There are many out there for RC planes and helicopters that will handle 40+ volts but deliver as low as 5
     
  4. dstuard

    dstuard TrainBoard Member

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    Voltage regulators only work on DC. It's still a good idea if you first convert the AC to DC using a bridge rectifier followed by a filter capacitor (250 mf 50V electrolytic), then use an LM317T or equivalent variable voltage regulator to set the output voltage to the desired value.
     
  5. lexon

    lexon TrainBoard Member

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    Use a diode like you were told in the Trains.com forum. Maybe two diodes. A 3 amp diode should work just fine. That will give you half wave DC. Radio Shack use to sell the 3 amp diode. I still have some.

    Rich
     
  6. CSX Robert

    CSX Robert TrainBoard Member

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    You could use multiple pairs of standard silicon diodes, each pair wired in parallel but with opposite polarity, and the multiple pairs wired in series with each other. Each pair of diodes would drop the voltage by ~0.7 volts.
     
  7. brahamfireman

    brahamfireman TrainBoard Member

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    Thats pretty much what a bridge rectifier is. 4 diodes, each pair parallel to each other.

    you must take the 1.4V drop into account when making one.
     
  8. dstuard

    dstuard TrainBoard Member

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    Diodes will work fine so long as you don't need a variable output (which was specified). Probably an easier way would be to use a wall dimmer switch to control the input to a wall-wart. The output of the W-W can then be varied. Low voltage under cabinet lighting uses this exact same approach.
     
  9. bucklaew

    bucklaew E-Mail Bounces

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    I tried something a little different. You have appliances that give up the ghost. Each comes with a plug that contains a power supply that is used to run the device. For instance. Power for remote switches works perfectly using a 9VDC power plug, thus taking the load off the power pack. Next I had one for 3VDC laying around doing nothing, so I used it to power the street light for my setup.

    My next project is to put a double pole single throw switch in the line of my DCS50 so I do not have to unplug it each time I use it.

    trainster,

    I happen to have a 14VAC output plug that was used with a defunct printer, that I use for my building lighting.

    Just my 2 pence worth.
     

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