12 volt pc power supply

| hey guys here's a pic of the completed fully operational 63 watt power | supply.
Looks fine -- not exactly hard to make :)
| it has 12volts ( acka tester with new 9volt) and a 5 volt feed
Well, you probably won't be using the 5 volt feed ...
| it has an old hard disk for load ( possibly replaced by a 12volt car | light later) and a 30 amp
That's what we normally do.
| I'm using it for foam cutting now and may use the triton on it if it | has sutable amps...
It should. It won't change 18 NiCd cells at 5 amps (the charger will complain about input voltage, or the power supply will either shut off or melt down (melting down is unlikely)) but it should do smaller batteries or lower rates just fine.
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400 watt switching power supplies are available for around $25 all over town. Most will adjust to around 13v and put out better than 15 amps on the 12 v lines.
The 5v is useful if you plan to run a CNC foam cutter.
BTW, 12v is usually just barely enough to do serious foam cutting with any wir elonger than about 30 inches. I am running 35v/5a and it is enough for 54" of 0.020 stainless steel.
-- Paul McIntosh http://www.rc-bearings.com
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Good to see you doing this but get yourself a 200W AT style supply. 63Watts is next to useless.

While these older supplies generate what appears to be a good 12V try measuring it under load. You might find it drops very quickly. One way to counter this is to load the 5V side with resistors BUT that only applies to the later supplies.

Forget the car light (assuming you mean headlight) any decent headlight will draw more power than unit can supply.

63W divided by 12V = approx 5Amps. Totally unsuitable, particularly once you add that load to get it running.
Imagine your charger can charge a max of 24 cells (as I believe the Triton does).
25cells x 1.2V nominal per battery x 0.5W for a basic charge rate approx 15Amps draw (note I'm simplifying here for those electrical experts out there)
Another way to see it is: 63W divided by 12V = 5.25Amps output. 15Amps max required vs 5.25Amps available...
End result is that the supply cannot support the loads you might be imposing from your charger. Oh, and don't forget to factor in your supply eats some power itself.

Take a look at this link. The conversion is the basis for mine, except that I use a more appropriate mains switch for my locale. http://web2.murraystate.edu/andy.batts/ps/powersupply.htm
1. Fit a proper illuminated switch on the mains side of the supply. Usually this will fit the old output socket intended to run computer monitors. 2. Fit some decent wire wound resistors to the 5V side to generate sufficient load that the 12V side comes upto 12Vs. 3. Fit the resistors with a suitable heatsink and mount them securely. 4. Use as many of the 12V+ and ground leads as you can to mount to your binding posts. 5. Fit a lamp to the 12V side (The light in the mains switch shows you power going in, the 12V lamp shows power going out - an easy visual to it working). 6. Remove all unused wiring. Clean the PCB, case, and fan of dust. 7. Test carefully, mains power can kill and poor output voltages can fry stuff.
Between a friend and myself, we've successfully converted about a dozen supplies. Average conversion cost is under $15 AUD allowing for the niceities of illuminated switches and 12V lamps (I also fit dual binding posts so I can run two chargers at once....).
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The Raven
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| | > hey guys here's a pic of the completed fully operational 63 watt power | > supply. | | Good to see you doing this but get yourself a 200W AT style supply. 63Watts | is next to useless.
I agree that a 200 watt power supply would be ideal, but 63 watts is hardly `next to useless'. Assuming that his power supply can put out 5 amps at 12 volts, he should be able to charge up to 8 cell packs at 4 amps, or 4 cell LiPo at 2.5 amps (the max that the Triton will do with LiPo, I think) ...
I fly a lot of electrics, and I don't have any packs that are large enough that I'd need more than 5 amps input into my Triton to charge them. I doubt I'm unique in this.
(Of course, I do have two Tritons and an Astroflight 110D. To use all three at once, I'd definately need more power, but for just one of them, 5 amps is usually enough.)
| > it has 12volts ( acka tester with new 9volt) and a 5 volt feed | | While these older supplies generate what appears to be a good 12V try | measuring it under load. You might find it drops very quickly.
Perhaps, but even if it can only do 4 amps, it's still useful.
| > it has an old hard disk for load ( possibly replaced by a 12volt car | > light later) and a 30 amp illuminated switch for control. | | Forget the car light (assuming you mean headlight) any decent headlight will | draw more power than unit can supply.
`Car light' covers a lot of ground, and your assumption is probably incorrect. My power supplies use a 12 volt car light (think brake light) on the 5 volt line to make the power supply happy. Works great.
| > I'm using it for foam cutting now and may use the triton on it if it | > has sutable amps... | | 63W divided by 12V = approx 5Amps. Totally unsuitable, particularly once you | add that load to get it running.
I disagree ...
| Imagine your charger can charge a max of 24 cells (as I believe the Triton | does). | | 25cells x 1.2V nominal per battery x 0.5W for a basic charge rate | approx 15Amps draw | (note I'm simplifying here for those electrical experts out there)
The Triton will draw up to 13 amps when charging the right battery at it's highest rate. But most people don't have those batteries, or could just slow the charge rate down if they needed to. Certainly, the Triton will let you know immediately and loudly if the voltage drops low enough to not make it happy anymore, and then you just lower your charge rate.
Also note that when charging, it's more up to 1.5 - 1.6 volts per cell that you need to put into the cell to charge it at a high rate. Possibly even a bit higher if it has a high internal resistance.
More appropriate math would be 24 cells * 1.6 volts * 5 amps / 12 volts. That works out to 16 amps, plus you'd have to add some percentage to cover the not 100% efficient charging circuits (especially the circuit that converts 12 volts to 36 or so volts), but I'm pretty sure the Triton slows down it's charge rate greatly when you get that many cells on it.
But either way, if you don't need to charge huge packs, 5 amps input will probably fit most of your needs with a single Triton.
| 2. Fit some decent wire wound resistors to the 5V side to generate | sufficient load that the 12V side comes upto 12Vs. | 3. Fit the resistors with a suitable heatsink and mount them securely.
Using automobile brake lights, and you won't even need heat sinks, and they're cheaper and let you know that it's on.
| 5. Fit a lamp to the 12V side (The light in the mains switch shows you power | going in, the 12V lamp shows power going out - an easy visual to it | working).
You're wasting 12v power there. Put it on the 5v side, let it be a bit dim. If you need it to be brighter, use a 6 volt auto/motorcycle bulb.
You also don't need an external switch if you use a AT power supply. You probably have the switch that came with the computer, so just use it instead. (Shorten the cable if needed, but other than that, it's simple.)
--
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Another option for wire cutting is to skip the pc power supply electronics alltogether. There should be a number of taps coming straight out of the transformer, and if you use an extra length of wire and an alligator clip you can have an infinately variable rheostat (which of course will be hot) to fine tune the current.

63Watts
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Which transformer are you referring to? Most PC power supplies are switched types. The voltage comes from rapidly switching transistors, not tansformers.
-- Paul McIntosh http://www.rc-bearings.com

power
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I stand corrected. I see some large inductors but nothing that looks like the traditional power transformer.
Of couse the alligator clip on some extra wire trick still works even if it is plugged directly in the wall, but someone somewhere has probably already burned their house down with that setup.

try
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Doug McLaren wrote:

The Triton internal dc-dc converter is only 90w output max. The input is 90w-100w max.
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I finally found a great source for 12V Power supplies.. It i
www.12vadapters.com. I use the 12V 5 Amp unit for almost all my D charging needs.... It is so much cheaper than buying the same components from an R specialty site, for less than half the price..
Anyone else has have a good source for components.
Thanks Jo
-- Joe Gulispi ----------------------------------------------------------------------- Joe Gulispie's Profile: http://www.rcgroups.com/forums/member.php?u 063 View this thread: http://www.rcgroups.com/forums/showthread.php?t )023
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DIY ex PC power packs at minimal cost:: refer PC Power Supply Conversion - Pat Harvey PC Power Supply - convert to power a 12VDC Battery Charger PC Power Supply Conversion (110/230 Vac to 12V ) under "Battery Chargers & DIY Power Supplies." at Alan's Hobby Model & RC FAQ Web Links http://homepages.ihug.co.nz/~atong
Regards Alan T.

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Joe Gulispie wrote:

I got a 10A CB mains-to-13.8v rig on ebay..
Love it.
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Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:
If you have (or can find at a dump) and old computer, pull the power supply out of it. Check the leads with a voltmeter. There will be at least one set of leads that is 12 volt (typically 5 amp. Out of pocket expense $0.00 Time - about 10 minutes to pull the power supply and another 5 minutes to locate the 12 volt leads.

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On Mon, 10 Mar 2008 19:59:54 -0400, Ted Campanelli

Not as simple as that, usually PC psu's will sense if there is no load and cut power after a while.
Theres an article on the web somewhere how to make a dummy load to make it work..

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Not only not quite that simple, but it's also not quite zero cost. I spent about $15 at Radio Shack for the banana plugs and other pieces and parts not including the power supply. However, if you get a big enough power supply, you can power two chargers for most needs. Also, one of the most useful features I found is that you can also provide a 5VDC source to power up a airborne system which you are doing set up or trouble shooting on the bench. BTW http://reckerclub.tripod.com/id105.html has a step by step with photos on how to do the conversion. There are other sites as well, but this one worked for me.
Tom
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Tom,
The Recker RC Club article on PC power supply conversion is the most complete and clearly written such article I've found. Thanks!
Randy
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here's one ready to go.
http://www.flyhurricane.com/product_info.php?cPath5&products_id 2&osCsidIfb51bcd602f4d6bfef1be2780993a6

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Joe Gulispie wrote:

As close as your nearest Walmart: http://www.walmart.com/catalog/product.do?product_id942756
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My visit to that link said "not available online" "not available in stores" LOL! I did make a power supply from a computer power supply. I put posts, banana plugs and auto plugs and a female ciggy socket on mine. Handy dandy thing. mk
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On Sat, 15 Mar 2008 03:07:57 GMT, Congoleum Breckenridge

Depends what you need, Most model PSU's are 15 amps, and once you get to that ampage they are just as cheap from a RC store as an electronics store.
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