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I am looking to build a power supply to power a 150 V DC armature motor that will pull a maximum of 4 A. The cheapest I have seen so far is the following on ebay.

I'm looking to build one myself but can't find anywhere online that will give me a guideline as to whats involved. Can anyone point me in the right direction

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  • \$\begingroup\$ Without following your link, what's your input voltage? \$\endgroup\$
    – shimofuri
    Feb 6, 2013 at 12:38
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    \$\begingroup\$ Granted the listing is priced in £ Sterling, I'm guessing 230V 50 Hz... \$\endgroup\$
    – user16324
    Feb 6, 2013 at 12:41

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I would look for a 230-110V transformer at your rated current, add a bridge rectifier and beefy capacitor, and start from there. You don't say if you are looking for PWM for speed control, but if you are, this will provide a decent supply for your PWM controller.

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  • \$\begingroup\$ I agree. 2:1 transformer seems to be usable in this scenario. \$\endgroup\$
    – Al Kepp
    Feb 6, 2013 at 12:50
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    \$\begingroup\$ Also, 110V transformers are reasonably common items for some reason! \$\endgroup\$
    – user16324
    Feb 6, 2013 at 12:58
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Out of safety, reliability and cost, choose any 2. For reliability you need overvoltage protection function because of back EMF. So lab supply will not work. Ordinary DC lab supply will die fast from back EMF. Because of high torque mode at start, the short term rush current should be about x5-x10 of nominal. So most of cheap regulated supplies will not work. With reliablity in place consider safety: the kill switch is a must for any schematics with high power motor running near humans. But it is not that trivial as simply breaking the supply current. The kill switch, emergency override (Red EMO mushroom button) should also involve an absorbing regenerative resistor to receive recuperated energy in break mode, when user or runaway-limit switch trips the EMO. And so on. So cost will be high if you need precise, DC, regulated, lab grade supply.

If the accuracy is not a requirement, then so named raw power supply is best option. Raw power supply should include only "dumb", highly reliable, exceedingly overrated parts with no much semiconductors, except diodes and overvoltage zeners.

Chassis, AC-connectors/grounding, AC-switch, AC-fuse, AC-filter, Rush current limiter AC-thermistor 10A, Transformer 230/150V 10A, Diode bridge 400V/20A, Capacitor bank (needs some calculations) about 10000-100000uF, slow DC trip/breaker 20-30A, overvoltage AC zener/TVS 175-190V rated for impulse current ~20-100A, 20-100W resistor ~50 Ohm with high voltage power transitor to automatically turn regenerative mode, 2 (for 2 human hands) low current mushroom EMO buttons, DC relay, few small parts.

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