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#218735 09/09/17 10:47 PM
Joined: Jul 2002
Posts: 8,417
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Trumpy Offline OP
Member
Hi Guys,
Sorry it's been a while, but I would like to design a device for testing PC boards in dairy sheds I do a LOT of fault-finding in.
Now I have most of it all sorted but the one thing I can't get through my thick skull, is how I'm going to power this tester (which will in turn power the board under test), it needs to have a solid 25.5VDC to the board and I was thinking batteries, but this thing needs to be reasonably portable, sure, the current draw from something like this won't be any more than about 200-300mA, to power the test solenoids.
Sure, SLA batteries could be an option, but I've never heard of a battery that has any more than a 24VDC output.
I was also thinking a switch-mode PSU inside the box (that I want to keep as small as possible, if I can) but then you'd have to have 230VAC to the box, which isn't intrinsically a problem, but it affects the portability of the thing.
Any ideas?

Joined: Jul 2004
Posts: 9,689
Likes: 10
G
Member
Google up DC/DC converter. That is basically a switching power supply with a DC input (battery?) and then outputs DC at a different voltage. Like a laptop power supply.

Last edited by gfretwell; 09/10/17 12:30 AM.

Greg Fretwell
Joined: Dec 2002
Posts: 205
G
Member
How about one of these? I know the Chinese suppliers get some bad press, and I would be very cautious about anything mains powered, but I have had a few electronic modules from here and found them perfectly OK. Cheap enough to experiment with too.

https://www.banggood.com/DC-DC-600W...Power-Supply-p-1041640.html?rmmds=search

Joined: Nov 2005
Posts: 826
J
Member
This is what I use:
http://www.mpja.com/XL6009-Adj-5-35V-DC_DC-Boost-Converter/productinfo/31397+PS/
They also have one with a built in meter:
http://www.mpja.com/Boost-Converter-Adj-4-35V-with-LED-Meter/productinfo/33525+PS/
I know it doesn't make sense for you to order from an electronics supplier in Florida, but I would imagine that you have similar suppliers there. Mine is added as a boost supply, to make a standard PC supply, useful for my bench. You might consider adding one to an R/C Li-Po battery or USB power bank.

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Joined: Jul 2002
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Trumpy Offline OP
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Woah! ,
Hey thanks guys, it's been a while since I've worked with DC-DC converters, but it's given me something to think about though!
Will let you folks know how I get on and post some pics of the finished (prototype) tester.

Joined: Jul 2002
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Trumpy Offline OP
Member
JoeTestingEngr,
It's a shame that Marlin P Jones don't ship to NZ, because the first one you posted looks exactly like what I'm after.
I've searched all the local places here and all they have is nothing I want, it's all like boost 5VDC to 12VDC, which is not really what I'm after.

Joined: Mar 2004
Posts: 947
T
twh Offline
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Joined: Nov 2005
Posts: 826
J
Member
I think you're good to go, Trumpy!
http://www.ebay.com/itm/like/121623601859?chn=ps&dispItem=1
I also found them at All Electronics and they ship overseas. Better still, just Google "XL6009 Module", and you'll find them all over creation. I just double checked mine and it has the older, LM2577 adjustable switcher, in it. The XL6009 switches at 400kHz, instead of 50kHz. You'll probably be able to get yours from where MPJA buys theirs. Just add a heat sink if you start pushing 10W, or if it feels hot to the touch.
Joe

Joined: Nov 2005
Posts: 826
J
Member
TWH,
The specific item that you linked to is a buck converter. Trumpy is looking for a boost converter. The good thing is that they're available on Ebay, Amazon, and many other sites. I was a little surprised to learn than I could buy 2 for $6.94, with Amazon Prime, and have them on Thursday. I just hope that I never get to the point of impulse buying switching regulators.
Joe

Joined: Jul 2002
Posts: 8,417
Likes: 3
Trumpy Offline OP
Member
Joe,
You are awesome, mate. beer
I managed to find a place called Surplustronics here that stock these modules, for the paltry sum of NZ$5.50 + freight.
Thanks so much for your help.

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