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  1. #1
    Join Date
    Oct 2015
    Posts
    6

    How to reduce output of a DC power supply.

    I have an 85 volt 8 amp Dc power supply that I would like to use on my plasma table for driving my steppers. Problem is my Gecko drives will only handle 80v max. Is there an easy way to reduce the output of an unregulated DC power supply to say 70 volts or so?


    Sent from my iPhone using Tapatalk

  2. #2
    Join Date
    Sep 2005
    Posts
    287

    Re: How to reduce output of a DC power supply.

    One way is to get some power diodes and connect them in series with the output.

    A general silicon diode drops approx. 0.6 - 0.7 volts across it. Therefore to drop 6 volts you'd have to connect 10 of them in series.

    Next you have to consider the rated power dissipation of the individual diodes. Find what the maximum amps will be that your power supply will ever supply and use that. Power = volts x amps so let's say the max amps from your power supply would be 8 amps then 8 amps x 0.7 volts = 5.6 watts. You would need at LEAST that power rating for each diode, but preferably higher for a good safety margin.

    I just happened to be buying some 5 watt diodes yesterday and they were priced at $1.65 each. However, those prices are high and you'll probably get them cheaper on Ebay, etc, or if you buy from China, a fraction of that price.

  3. #3
    Join Date
    Dec 2003
    Posts
    24216

    Re: How to reduce output of a DC power supply.

    Another way is to remove some turns off of the secondary, for a E I transformer it is around 3 to 3.5 turns/volt, or 1.5 to 2 turns/volt for a Toroidal.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  4. #4
    Join Date
    May 2006
    Posts
    4043

    Re: How to reduce output of a DC power supply.

    You might put a 12V 8A Transformer in series (backwards)

    https://www.digikey.com/product-deta...717-ND/4878646
    TK
    http://dynomotion.com

  5. #5
    Join Date
    Jan 2005
    Posts
    15362

    Re: How to reduce output of a DC power supply.

    Quote Originally Posted by Joe 66 View Post
    I have an 85 volt 8 amp Dc power supply that I would like to use on my plasma table for driving my steppers. Problem is my Gecko drives will only handle 80v max. Is there an easy way to reduce the output of an unregulated DC power supply to say 70 volts or so?


    Sent from my iPhone using Tapatalk
    And another way is to control the input Ac power, with a simple light dimmer that can handle the amp draw, or something similar, I would not go the diode way if it fails then you may damage drive
    Mactec54

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