Is an ac drill an inductive load or a resistive load?

Discussion in 'The Projects Forum' started by Max12345, Oct 22, 2013.

  1. Max12345

    Thread Starter Member

    Aug 27, 2013
    Greetings all
    In a different thread, Dodgydave advised me " to use a light dimmer to alter the wattage" to reduce the power of a soldering iron.
    I now want to build one because it will cost a tenth of a commercial one.
    However, I thought of building a unit which could be used to control the power of the soldering iron AND the speed of my drill.
    Most of the circuits I came across on the net specifically stipulate that the dimmers may NOT be used for inductive loads, only for resistive loads, like incandescent bulbs, EXCEPT if the ac motor is universal, which means it can work with ac or dc, and has brushes.
    My drill only works with ac but has brushes (see attachment 1).
    1. Is this a universal motor or an inductive one?
    Attachments 2, 3 and 4 are dimmers which claim to work with both types of loads.
    2. Is this wise or possible?
    Attachment 5 shows what looks like a good resistive dimmer from Circuitstoday.
    3. Why does it not have or need a choke as I have inserted?
  2. strantor

    AAC Fanatic!

    Oct 3, 2010
    Your drill is both a universal motor AND and inductive load. I don't anticipate it working well with a dimmer. However you can get a "dimmer" for your drill cheaply. Search for "router speed control"

    P.s. you could run the drill motor on DC if you wanted to, but the finger trigger circuit probably wouldn't work.
    Max12345 likes this.
  3. MaxHeadRoom


    Jul 18, 2013
    The variable speed control included with hand tools use a form of Triac 'Dimmer' circuit, the main difference I have seen is the inclusion of a snubber of some kind used in these.
    As shown in the attachments.
    The inclusion of a choke can also be used in the between triac and motor.
    How the attachments are worded can be a bit misleading as it just blanket mentions AC motors, whereas AC 1ph induction motors do not take well to variable speed.
  4. Max12345

    Thread Starter Member

    Aug 27, 2013
    Thanks for the replies, strantor and MaxHeadRoom, that answers my questions very well.