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  1. #21
    Join Date
    Apr 2013
    Posts
    1899

    Re: Fried a power supply

    Quote Originally Posted by mactec54 View Post
    The fuse is only for the main input power supply 120v / 240v Ac there is no protection on the DC side of these power supplies
    I see... not the way I'd design it...

  2. #22
    Join Date
    Apr 2013
    Posts
    1899

    Re: Fried a power supply

    Quote Originally Posted by rotccapt View Post
    Thank you for the info, I'm going to build the circuit I posted and am looking at switching the 5v control. If I can't do that I will move my relay to the DC side between the ps and the protection circuit
    Why not start with building an analogue PSU instead? All it needs is a transformer, a rectifier and a large capacitor. You are much better off with that than using a switching PSU + your circuit.

  3. #23
    Join Date
    May 2012
    Posts
    40

    Re: Fried a power supply

    Main reason is my motor speed control can only take up to 25v, I have not looked but I know a 24v ac transformer will produce close to 30v dc, I also already have the ps

  4. #24
    Join Date
    Mar 2007
    Posts
    2083

    Re: Fried a power supply

    I take the 25V limit is because the speed control is designed to be powered by 6 Lithium polymer cells
    that can absorb any returned energy (unlike the 24V switch mode power supply)

    if you protect the power supply with a diode
    I expect the speed control will be at more risque unless you add a shunt stabiliser / returned energy dump across the speed controls supply terminals

    without a circuit diagram or speed control board to study is impossible to tell how high a supply voltage the board can survive
    unless the speed control came with detailed specifications

    John

  5. #25
    Join Date
    May 2012
    Posts
    40

    Re: Fried a power supply

    You are correct about the voltage limit. I do not have any detailed info on the speed control. It is rated at 80A and can handle 1 to 6 lipo cells

  6. #26
    Join Date
    Apr 2013
    Posts
    1899

    Re: Fried a power supply

    Quote Originally Posted by rotccapt View Post
    Main reason is my motor speed control can only take up to 25v, I have not looked but I know a 24v ac transformer will produce close to 30v dc, I also already have the ps
    OK, in that case I'd add a simple voltage regulator circuit or would chose a transformer suitable for the purpose. You don't need to buy one with 24VAC secondary... 18VAC is pretty common. But sure, since you already have a PSU you might as well use that one until it lasts or you get tired of the fan noise, assuming it has a fan.

  7. #27
    Join Date
    Dec 2005
    Posts
    160

    Re: Fried a power supply

    2 MOV's rated at 160 joules 36vdc
    each and a large filter cap as his motor is pulling about 200w
    Attached Thumbnails Attached Thumbnails MOV160joules.JPG  

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