Power supply for a DIY electromagnetic vise

I am making a electromagnet from two microwave transformers. I have tried several power supplies but they all trip on and off. i need one that does 8 to 10 amps output and between 10 to 15v without tripping. Any ideas

Hi, Please check out this list of filtered results for 160-180W GlobTek Desktop power adapters which should work for you. :crossed_fingers:


Good luck!

1 Like

Check the DC resistance of your electromagnet to verify the current requirement.
Be sure to zero out the leads of your ohmmeter since the resistance is likely below 200 ohms.
Then use Ohm’s law to determine the current requirement.
Amps = Volts / Ohms

Add five to fifteen percent to the amps calculated to account for measurement tolerances (assumes meters costing less than $200.00US).

If the power supply’s rated current is greater than the coil current you determined, then any reputable brand (all of the ones Digi-Key carries) will work.

Also be aware that when power is removed from a DC energized coil there will be a large switch-off spike that can damage a power supply. Normally the spike is dampened using a snubber circuit, often just a flyback diode.

Thank You, Paul I did already buy the Shockey diodes for flashbacks. I did not know how to calculate the current need. very helpful. I have 0.4 ohm resistance on each coil 0.7 on two when connected in series. from what I calculate, I see my need for a 12v 20amp power supply?

Yes, with a 0.7 ohm load @ 12VDC you’ll want a 20 A supply.