Harbor freight router speed controller question on where extra power goes

Discussion in 'General Electronics Chat' started by RogueRose, Aug 7, 2016.

  1. RogueRose

    Thread Starter Member

    Oct 10, 2014
    This controller is good for like 1500-2000 watts

    I have hooked it up to two old motors (1/4hp and 1/2hp) and they run well when the dial is in the upper part of the middle section but makes a strange sound (like a switching polarity slower maybe??) at anything lower and even goes into a full stall in the low setting and just entering the medium section of the dial - the sound the motor makes is kind of like the hum of a flourescent or neon ballast. IDK if this is because the type of motor that I'm using (these are probably 40+ year old, heavy - 20-30lbs) or if this is what is to be expected.

    I have a rotozip that has a speed adjustment from 10,000 - 35,000 rpm (Dremel tool 5,000 - 35,000 rpm as well) and they both have what seems to be a potentiometer but the motor doesn't sound as different when it goes to the low speeds like the router speed controller.

    Another question is if the motor draws 4.5A @ 120v and I use the controller to slow it by 50%, does it still draw the same amount of energy and disippate as heat, or does it reduce power intake? This is really important as I don't want it melting or catching fire if left on for 24 hours.
  2. tcmtech

    Distinguished Member

    Nov 4, 2013
    Are they high-speed universal type motors or regular induction motors?

    If they are regular induction motors they are not speed controllable by one of those devices and you will just burn them and or the controller out trying.

    Why are you running your router for 24 hours?

    Do you think it's dissipating the energy? o_O

    Does it get burning hot like its dissipating a few hundred watts of energy? :rolleyes:

    Basic reasoning and deduction ( and some proper online searches for how those devices work) should be able to tell you what it's doing? :oops:
    Last edited: Aug 7, 2016
  3. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    Are the motors induction, or wound field, and in this case shunt or series wound, or something else?
  4. MaxHeadRoom


    Jul 18, 2013
    That controller only works on Universal motors as it comes, if wishing to use a DC brushed motor then a Bridge rectifier is needed.
    An induction motor on these will drop out of run at low rpm. Especially if on load.
    They are simple Triac type.
  5. crutschow


    Mar 14, 2008
    As tcmtech noted, that speed controller won't work well on induction motors, which is what most small AC motors are.
    It's designed for universal type motors such as found on routers and vacuum cleaners.
    If you notice in the description, it only mentions routers.
    What did you intend to use it for?
  6. RogueRose

    Thread Starter Member

    Oct 10, 2014
    Thanks for the explanation between the universal and induction. The motor I tried on was induction so I see why it wouldn't work. I now understand how to identify a universal vs induction motor so that is a big step in the right direction! Thanks again for the help!