$2 DIY bench power supply for testing emitter and powering a hobby charger.

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JohnnyMac
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$2 DIY bench power supply for testing emitter and powering a hobby charger.

I recently received my Imax B8+ charger and have been trying to get a 12v power supply ready for it. Since I could also use a decent bench supply for other voltages I figured I'd go the usual route (cheapest) and make my own. I finally got the last of the needed parts yesterday so I began the assembly. All that is left to do is complete the internal wiring and that will happen tonight.


I am using an old computer power supply (psu) for the internals. This will provide me with 12v, 7v, 5v and 3v supply. I found a cigar box the perfect size to just fit the psu along with some external fan grills I had in the basement, a master switch ($1), and a speaker connector panel I picked up at Radio Shack on clearance for $0.87). Total investment? $2

Here it is so far:
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Zoom in (real dimensions: 800 x 600)Image
Zoom in (real dimensions: 800 x 600)Image
Zoom in (real dimensions: 800 x 600)Image

On the inside it looks like this. Just remember that the wiring is not completed and will be greatly cleaned up inside:
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Zoom in (real dimensions: 800 x 600)Image

Pretty darned wesome what $2 can still buy these days! ;)
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Johnny
Edited by: JohnnyMac on 03/25/2013 - 12:12
dthrckt
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Sweet!

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garrybunk
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That is Sweet!  I wouldn't mind building one myself.  Did you follow any particular "DIY Guide" to build it, or just do it?  (ie. do you have any links for the procedure?)

-Garry

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funkstrong
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How many amps you think if coming out of the 12v rail? I’ve got a bunch of old power supplies, this would be handy since I’ve already managed to fry a led by “testing” different batteries.

JohnnyMac
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garrybunk wrote:

That is Sweet!  I wouldn't mind building one myself.  Did you follow any particular "DIY Guide" to build it, or just do it?  (ie. do you have any links for the procedure?)

-Garry

Here you go, Garry!

http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Powe...

peterloron
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Nice build! I have an ATX supply I hacked into a bench supply, although I put the banana jacks ad master switch right into the metal case of the PSU.

One thing to note: these power supplies are not current-limited the way a proper lab supply often is. You can easily short many amps through something if you are not careful. Easy to let the magic smoke out.

Oh, and excellent cigar selection as well!

gords1001
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awesome job, love it. 8)

JohnnyMac
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funkstrong wrote:
How many amps you think if coming out of the 12v rail? I've got a bunch of old power supplies, this would be handy since I've already managed to fry a led by "testing" different batteries.
Here is what they claim for an average 300W supply:

apt323
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Thanks for the information! I have numerous atx supplies in the garage that I couldn’t part with! Now look what i can make. The woman will be so happy that i have another BLF inspired project. Lol

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Zeus33
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Nice job Johnny!

sanka
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I have never seen a power supply enclosed in Spanish Cedar. Very creative!

JohnnyMac
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Thanks, guys!  Yeah, even my step-son came home last night with his girlfriend and saw it on the kitchen table. He came into the living room where I was and asked, "did you make a power supply inside a cigar box?".  I replied, "yeah, man" to which he said, "that's awesome!"  :bigsmile:

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Very nice project JM Kudos :bigsmile:

garrybunk
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JohnnyMac wrote:

garrybunk wrote:

That is Sweet!  I wouldn't mind building one myself.  Did you follow any particular "DIY Guide" to build it, or just do it?  (ie. do you have any links for the procedure?)

-Garry

Here you go, Garry!

http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Powe...

Thanks for the link!  I actually started Googling and found that link in addition to this one: http://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/#intro

-Garry

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Don
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AT PSU’s are even easier to convert.

If you happen to have them lying around. I think I have about 50 of them so anyone within 3 hours drive of me can have one for free. It’ll help clearing the crap from my house.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Zeus33
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Issue of the Resistor

Power supplies need a certain minimum load to work properly. The min. load for mine is around 0.8 amps. Thus if you plan on powering LED’s or other such low-power device exclusively, you’ll need a resistor to provide a load. Otherwise you will damage the PSU.

A meaty 10-Ohm, 10 watt resistor from Radio Shack is a good choice. Wire it across 12 volt and ground.

garrybunk
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Zeus33 wrote:
Issue of the Resistor Power supplies need a certain minimum load to work properly. The min. load for mine is around 0.8 amps. Thus if you plan on powering LED's or other such low-power device exclusively, you'll need a resistor to provide a load. Otherwise you will damage the PSU. A meaty 10-Ohm, 10 watt resistor from Radio Shack is a good choice. Wire it across 12 volt and ground.

One of those articles also suggested wiring it so that the cooling fan became the load.

-Garry

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Zeus33
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garrybunk wrote:
One of those articles also suggested wiring it so that the cooling fan became the load.

-Garry

Excellent idea!

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interesting! I wonder if one of these could be used to do home anodising? Most guides I read specify a certain amount of current per surface area, whereas these are voltage controlled instead. It certainly would make it a whole lot cheaper if it would work.

Don
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Current for anodising is best at lots of amps. Preferably more than your typical PC PSU can provide. The more amps the better (generally).

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

moderator007
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Don wrote:
Current for anodising is best at lots of amps. Preferably more than your typical PC PSU can provide. The more amps the better (generally).

That greatly depends on the size of item being anodized. I have read through post that did use a computer power supply for anodizing with small pieces. I use my automotive battery charger to anodize with. It works well with a small host like a cut down mini mag with very good results. I tried a full sized 2D Maglite one time and didn’t turn out so well. The current wasn’t high enough for the amount of surface area in the mag.
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JohnnyMac
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moderator007 wrote:
Don wrote:
Current for anodising is best at lots of amps. Preferably more than your typical PC PSU can provide. The more amps the better (generally).
That greatly depends on the size of item being anodized. I have read through post that did use a computer power supply for anodizing with small pieces. I use my automotive battery charger to anodize with. It works well with a small host like a cut down mini mag with very good results. I tried a full sized 2D Maglite one time and didn't turn out so well. The current wasn't high enough for the amount of surface area in the mag. . Rit clothes dye from wally world, Sunshine Orange. ! photo DSC00694.jpg!
WOW!  Shocked :bigsmile:
mattthemuppet
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thanks, I’ll have to go back and read the mtbr thread about it and see how much current I would need..

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Also, you can easily get voltages that aren't officially supplied by the PSU. For example using the +12v as positive and +5v as negative will give you the difference between them, in that case 7 volts.

AlexGT
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Nice work! I like the enclosure!

If you need a bigger power supply with way more amps you can also convert a server power supply.

How many amps would you need to properly annodize a 2C mag? My power supply can deliver up to 150amps at 13.8v, would that be enough?

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Pretty cool, JM !!!

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Shadowww
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JohnnyMac wrote:

Here is what they claim for an average 300W supply:


Those supplies should NOT be used with anything expensive and valuable, such as expensive hobby chargers.
See this review of one of them to see why: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=324
I’m not going to quote the full review here, but this picture of ripple on 12V rail should be enough:

That’s at 300W btw.. Here’s for comparison Corsair AX1200i at 1200W:

JohnnyMac
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Shadowww wrote:
JohnnyMac wrote:

Here is what they claim for an average 300W supply:

Those supplies should NOT be used with anything expensive and valuable, such as expensive hobby chargers. See this review of one of them to see why: http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=324 I'm not going to quote the full review here, but this picture of ripple on 12V rail should be enough: !http://www.jonnyguru.com/modules/NDReviews/images/HerculesHRC512F/Oscope...! That's at 300W btw.. Here's for comparison Corsair AX1200i at 1200W: !http://www.jonnyguru.com/modules/NDReviews/images/AX1200i/Scope/Test8-12... link and your pics are no good.  404 error.

If they are no good for use with expensive electronics then there are a whole lot of computers (lots of expensive components in there) costing hundreds and thousands of dollars at risk that use them.  Someone had better tell Apple, Dell, HP, Compaq, Asus, Gateway, Toshiba, etc...

JohnnyMac
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I completed the wiring over the weekend and fired it up last night.  Works a treat!  Whisper quiet and puts out voltage in my choice of 24v/12v/7v/5v/3.3v

Fired up the new IMAX B8+ and it works great.  Looking forward to going through my cells and running discharge tests to filter out the older bad ones from laptop pulls and to get some good matched sets. Smile

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Is the 3.3v output close enough for driving a single emitter?  Say testing with a single Li-Ion max 4.5v driver.  If not, would you use the 5v output with a resistor or something? 

-Garry

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comfychair
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I think there's enough wiggle room in the specs for a '4.5v' driver to run fine on 5v. I haven't found one yet that isn't happy running even from 2xCR123As.

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