Switching power supply...


At my last job, PCB assembly, I got an old, but top-quality 24 volt solder iron and a load of A-quality tips. To power the steppermotors of a CNC-machine I'm building I'd also like to have a beefy 24 V powersupply.

I do have a lot of 12 volt equipment though and could use a better 12 volt supply as well.

With batteries it's no problem doubling the voltage. But... could I also buy 2 identical 12 volt switching power supplies and use those to create 24 volt safely or would it be an invitation to disasters ? I won't be using 12 and 24 volt equipment simultaneously.

Thanks in advance,


Yes, wire the 12V supplies in series. +12V A becomes +24. -12V connects to +12VB. -12VB becomes 24V return.

How many amps do you need to buy? http://www.mpja.com/prodinfo.asp?number=16032+PS others available as well.

Ah - Netherlands, never mind. There are comparable European surplus sites?

Thank you, that makes a lot possible !

I probably need 6 amps max at 24 volt, guess I'll stay under 10 for a while in the future and would like to operate the supplies at no more then 60-70% of their capacity. 2 x 15amps should be more then enough.

Shipping costs indeed ruin a lot and I haven't found really interesting surplus-shops locally yet. (started "playing" with electronics again 2 years back) But I'm pretty happy with ebay.

make sure they are isolated supplies. things like computer supplies tend to go into protection if you try to put them in series.

I have been thinking of using a PC-supply, but rather have 2 12-volt only supplies like the one on Crossroads message. I hope you mean checking whether their enclosures are electrically insulated/not connected to the negative output... since I wouldn't know what to check else.

Isolated meaning that the 12V return is not connected to the ground wire coming into the supply.

That... will be no problem. My friend multimeter should tell me enough :)

Problem is that I do have lots of interest in electronics, but when it comes to mains calculating the load of each group is about the best I do :roll_eyes:. I'm hardly interested to be honest. While soldering I'll of course be present..., but watching every 2-X hour CNC-job ?

This setup would really be great, I'm very interested in building an atmega-version of an 8051 AVR-based stepper driver which uses DACs for microstepping and tda2030 chips. I read a zillion threads on CNC and also collected most mechanical parts by now, I'd better not start counting in months of completion yet, but... I'm certainly a step closer, thanks !

Shipping took a while, but I received my 2 powersupplies and the solution works perfectly !

Thank you all for responding !