dc variable speed motor power supply

Discussion in 'General Electronics Chat' started by akolo georges, Feb 16, 2011.

  1. akolo georges

    Thread Starter New Member

    Jan 7, 2011
    1
    0
    i want to power my small homemade lathe with universal motor commonly used in sewing machines, i need to produce a dc supply to power it. from 220v main supply
     
  2. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    For starters, if truly a sewing mach. motor, the bulk of those are meant to run on 120vac, via an footpedal rheostat.........which would provide quite a wide window of speed control for a small lathe. So why would you want to bother with a DC arrangenent ??

    I use a converted {{ rewound with a heavier duty Nichrome spring for better amps }} sewing mach. footpedal rheostat to provide speed control for my 120vac Dremel, also a 'universal motor' -- which works like a charm.
     
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  3. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    Buy or build a full wave light dimmer. Dimmers work well with universal motors. I had one on my hand drill for ages.
    There are tons of circuits on the web.
    You DO have an isolation transformer, right? Experiencing the wrath of unbridled mains power will garner your respect in a flash-a big flash.
     
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  4. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    Doesn't an isolation transformer........1:1........ have equal amperage potential on the secondary, aka just as dangerous as open mains ?
     
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  5. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    The transformer will only deliver as many volt-amps as it is rated for (without burning up). If you have a 240VA transformer operating with a 120v constant voltage main (like a normal main would be), you can tax the secondary for 2amps max (120 * 2 = 240). The primary will then consume an equal 240 VA from the main. A smaller xfmr will have less VA and correspondingly less current to use.
     
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  6. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    The sewing-machine motor could be designed for 120V, 220V, 240V or some other value, depending where it was designed to be used and with what type of controller. It would be a good idea to check the motor rating, rather than making any assumptions about it
     
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