Connecting PSUs in parallel

Not simply, no.

That is one way, but its very fraught.

Must be an easier way.,..

If your looking for a 12v supply then nearly all PC PSU have more current than that example. Plenty of 300w supplys have 34 Amps.

If this is a 12V car tyre type compressor, then I'd be very surprised if you couldn't run it off a 300W ATX PSU. They draw around 7A.

However, because it's a brush motor running at a relatively low speed, they're very spikey in their current consumption. As such, I'd add a big capacitor across the 12V output.

I'll work back from the PSUs I have to see if any of them can produce a suitbable current.

Richard

Indeed it is such a device, or rather it is this one:

The search for maximum amps from this PSU is based on the thought that I'll be able to use it to test bits off the cars without having to resort to dreadful contrivances with car batteries.

Richard

Hmm, I find a portable jump-starter to be very handy for stuff like that. Much easier to carry around than a car battery, and very convenient when you have no mains.

This type of thing:

Hmm. 300w/12v=25A the way they taught ME maths..

Ah. An other peace ov meeningless inglish

Oh..don't piss around. Go to ebay and find a 10A or better ex CB 13.8V power supply.

Regulated and smoothed and do the business.

True, but I have a fair selection of ATX PSUs sitting on a shelf collecting dust. Building a lab PSU with one or some of them will be considerably less expensive than a portable jump starter.

And I like the complicated solution!

Richard

Connect 2 ATX 5 volt outputs in series. 12 volts, or ten. the pump will not notice the difference that much.

You will, of course, have to make sure that the 5 volt 'good' cable is connected up the right way, or the PSU will not start.

Dave

I got a jump start pack from Lidl for 20 quid. Has a built in compressor. Gets used as a 12 volt source for testing heavy current car bits - my bench top PS is restricted to 5 amps.

I didn't expect the SLA battery to last, but it's some 3 years old and still going strong. Has been used to jump start a few cars too.

posted a link to and do some basic maths before posting.

MBQ

Hi

You would only be able to do that if the units were floating from mains earth. All ATX power supplies I've ever seen are class 1 and would be dangerous to operate with a disconnected earth.

Steve

will short one of them out nicely via the earth wire, which may get quite hot under the gross overload if it doesnt shut down. Works fine if you disconnect the pcb in one from the case of course.

NT

You've also got to consider peak vs. contiuous ratings on some of these

I believe that I am still allowed to provide my own entertainment provided it does not interfere with anyone else.

As you may have seen, if had you bothered to read the whole thread, I have surplus ATX PSUs gathering dust. These are, possibly, going to cost me less than anything I can find on Fleabay.

Richard

Good point

Class 1 just means that it requires an earth to operate safely, it doesn't mean that the output is necessarily referenced to earth. I didn't have a spare ATX supply to hand but an old AT one I checked has floating outputs so it'd be worth the o/p checking his ATX units.

Note that when you connect the PSU to the mobo in the case the 0V will be connected to earth via the fixings but that is an EMC issue.

All very tecnikul. Wossa bindin post innit?