My system needs DC power input--maximum of 250W @ 24V--but with the use of an A/C power source. How do I go about this? I have no idea where to even acquire a DC power supply, but I'm not sure if that is the correct angle, as they're pretty pricey.

I am a mechanical engineering student, in his final semester. For our group's Capstone project, we made a shredder, and now just need to power it.

We purchased a 250W, 24V DC motor, along with a proper PWM DC Motor Controller to control its speed. The controller listed requires DC power in. https://www.amazon.com/RioRand-Controller-Efficiency-Generating-Protection/dp/B007TH4EN6

So far, I have wired the motor to the controller, and the controller to a "generic" wall plug from Lowe's. The third prong (ground) cable was left alone, as neither the motor nor controller has a spot for securing it. https://www.lowes.com/pd/InSinkErator-Power-Cord-3-ft-3-Prong-Black-Garbage-Disposal-Appliance-Power-Cord/1269937

The hot wire is attached to the power (+) terminal, and the neutral into the power (-) terminal. Then the motor is attached appropriately (but the ends can be swapped around based on which direction I want the motor to spin).

How would I have my DC system above powered with an A/C power source? I was tempted to go ahead and plug it into the wall, but don't want to risk frying any parts.

Thank you!


1 Answer 1


Your PWM controller has "polarity protection" but this does not mean it can accept AC (alternating current, where polarity switches at a frequency). According to the link, it can accept 12 to 40 volts DC input.

PWM Controller

As you've noted, two terminals connect to the motor, and reversing them changes the motor direction. The other two terminals are for DC input, labeled negative and positive.

In fact, in the link you provided, the manufacturer/seller has this image:

Caution statements

In short, do not connect this directly to mains power!

What you need is an AC-to-DC converter or power supply. Because your motor is 250 watts, you will want a converter (aka power supply) that can provide that as a minimum. Consider a Meanwell LRS-350-36 or something similar, which is a 350 watt supply that accepts multiple input AC voltages (120V, 240V), outputs 36 volts DC, and is relatively inexpensive.

  • 1
    \$\begingroup\$ +1 (new account :c ) Thank you so much for your replies! I figured as much, and was scouring for such a power supply, and the one you suggested is sweet! Apart from that, I was told about using a rectifier--would introducing that into the circuit (between the power plug and the controller) work as well? One I considered using: ebay.com/itm/… Or is it not that simple? \$\endgroup\$
    – user298278
    Commented Oct 20, 2021 at 22:45
  • 2
    \$\begingroup\$ A rectifier is the central function of an AC-to-DC converter. It would only give you DC with no voltage step-down, filtering, regulation, over-current protection, etc. -- these are the extra functions of the power supply suggested, which make it proper/safer to use. \$\endgroup\$
    – JYelton
    Commented Oct 20, 2021 at 23:48
  • 2
    \$\begingroup\$ Just an addendum: It may be that you are seeing "AC-to-DC converter" and thinking a rectifier will do the job much less expensively. This is a case where terminology is a little vague. A rectifier converts AC to DC, and only that. A power supply (which unfortunately can also be called an AC-to-DC converter) has additional functions that make it a much more robust solution. \$\endgroup\$
    – JYelton
    Commented Oct 20, 2021 at 23:50
  • \$\begingroup\$ I had a feeling that was the case. Thank you so much for the help! Power supply's on its way! \$\endgroup\$
    – user298278
    Commented Oct 21, 2021 at 13:35

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