Joining Computer power supplies - Electronic Circuits Projects Diagrams Free

chiba · 13th January 2007, 09:50 PM

I'm trying to come up with a cheap (read unregulated) 24V power supply that could handle around 12A. It's for powering a 24V dc motor attached to a speed controller. I know it would probably best be done with a Toroid, bridge and some caps but i remember seeing a page that hacked pc power supplies together. I know they can be joined in parallel without two many dramas but what happens if two switchmode pc power supples are joined in series? If anyone can help with what needs to be done or if they have a page that shows how then i'd be greatly appreciative.

**Nigel Goodwin** · 14th January 2007, 09:53 AM

You simply have to disconnect the secondary of one of the PSU's from chassis, otherwise it shorts the other PSU out.

How big are these motors?, is 12A the running current? - you need to bear in mind the massive starting current and stall current.

justDIY · 14th January 2007, 01:25 PM

just don't let the chassis touch each other, then you don't have to modify their wiring. for best results, the power supplies should be as identical as possible.

as Nigel's pointed out, your motors may have much greater current demands at startup and if they stall. does your controller support soft-start of the motors? having a massive current draw hit those switchers will probably trip some internal safety regulator and shut it down.

oh, don't forget to give each switcher a minimum load on each of the rails - typically 1-2 amps.

Sceadwian · 14th January 2007, 03:28 PM

Running switch modes in series like that is bound to be a pretty noisy business, but if it's just driving a motor..

chiba · 14th January 2007, 08:44 PM

Thanks guys, I tested it to 15A @ 24V, not bad considering these were rescued from the scrapheap. The motor is rated at 12A max, it won't see anywhere near that when running, but i wanted to make sure they could reach it.

13th January 2007, 09:50 PM	(permalink)
chiba Experienced Member	Joining Computer power supplies I'm trying to come up with a cheap (read unregulated) 24V power supply that could handle around 12A. It's for powering a 24V dc motor attached to a speed controller. I know it would probably best be done with a Toroid, bridge and some caps but i remember seeing a page that hacked pc power supplies together. I know they can be joined in parallel without two many dramas but what happens if two switchmode pc power supples are joined in series? If anyone can help with what needs to be done or if they have a page that shows how then i'd be greatly appreciative. __________________ 2.4Gigglehurtz

14th January 2007, 09:53 AM	(permalink)
Nigel Goodwin Super Moderator	You simply have to disconnect the secondary of one of the PSU's from chassis, otherwise it shorts the other PSU out. How big are these motors?, is 12A the running current? - you need to bear in mind the massive starting current and stall current. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

14th January 2007, 01:25 PM	(permalink)
justDIY Experienced Member	just don't let the chassis touch each other, then you don't have to modify their wiring. for best results, the power supplies should be as identical as possible. as Nigel's pointed out, your motors may have much greater current demands at startup and if they stall. does your controller support soft-start of the motors? having a massive current draw hit those switchers will probably trip some internal safety regulator and shut it down. oh, don't forget to give each switcher a minimum load on each of the rails - typically 1-2 amps. __________________ If you don't have a planet, what good are gold bars? want to contact me directly? gmail gordonthree check out my project website: http://projects.dimension-x.net Favorite numbers: 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

14th January 2007, 03:28 PM	(permalink)
Sceadwian Experienced Member Blog Entries: 1	Running switch modes in series like that is bound to be a pretty noisy business, but if it's just driving a motor.. __________________ Curiosity killed the cat; That's why they have nine lives.

14th January 2007, 08:44 PM	(permalink)
chiba Experienced Member	Thanks guys, I tested it to 15A @ 24V, not bad considering these were rescued from the scrapheap. The motor is rated at 12A max, it won't see anywhere near that when running, but i wanted to make sure they could reach it. __________________ 2.4Gigglehurtz Last edited by chiba; 14th January 2007 at 08:46 PM.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Latest
ATX Power unit Problem	Gayan Soyza	General Electronics Chat	2	20th December 2006 02:59 AM
[help] Power consumption issue on bullet counter project *	Lanzer	Electronic Projects Design/Ideas/Reviews	13	26th August 2005 06:06 AM
Power supplies in TVs, VCRs, etc	ljcox	General Electronics Chat	25	18th April 2005 06:58 PM
Still looking at power supplies	Scarr	General Electronics Chat	3	27th December 2003 02:47 PM
UPS (uninteruptable power supply) for computer	Maury	General Electronics Chat	6	26th August 2003 12:06 PM