Dark asylumn

Ok guys I am heading to radio shack to pick up a few 10/10 resistors and a few 10/1 resistors.  I have read the posts but to me the information gets jumbled  I will follow the initial guide but m question is  what would be the correct  configuration for the resistor  I am buying enough of these so that anything you all tell me to do I will have plenty to choose from   radio shack is and hour away[]  I am stellar at some electronics but when it come to resistance I fall really really short. so if all the original information is correct  then I just need the new/best resistor setup.  Thank you guys I have like 10 ps that I can convert if I like the outcome

Dark asylumn

Wow I just finished up.  took me about 45-50 mins of actually doing it.  Took me 8 hours to read all the posts, reread all the posts, read all the useful links, rereadind the useful links, worrying about in-countering gray wire problems, problems with it not being able to stay on when charger is connected, just a little worry wart. It fired right up no problems what so ever. tested it with cover off, worked great, put cover on no power, remembered a post I had reread, tested posts 12.06v, took cover off (4 small screws no big deal) turned switch, fired right up. the wires for the posts were hitting the fan. Remember just because the fan isn't moving doesn't mean it not on lol. Thank you so much Andrew and everyone else that posted.


only thing I am wondering about?
 when I check the 5v and the 3.3v  they show up as the voltage they are suppose to but my tester says they they are "bad"  shows "good" on the 12v side.  Is that because they are using a 12v ground, not the respective -5 and -3.3 grounds (the white and the what ever color the other - was)

I have 2 green wires one I left unhooked. Is that right?

As for as the led
is it the led resistor to the -  side? I specialize in custom led automotive lighting and on 12v I put them on the + side. Is it something about the power supply make you have to do that?

And with the led is it better to go on a 5v or the gray wire?


oh yeah choosing which resistor setup was decided was best took me another hour to figure out. ended up going with the 4 1Ohm/10watt in series. drops to 11.74v while charging. fine with me it was a ps I took out of my throwaway pile, because I have no use for a 250w 14a ps lol. glad I stumbled upon this thread b4 I made my junk run. It will only be used for my nimh's

Have had it charging my nicd for 20 mins and the resistors ar at 89 coldest one 100 hottest one so no probs there.

and again  Thank you all so much. Without this thread I would have never done this. I have wondered for awhile if it was possibe.

IT IS AND ITS REALLY EASY. DONT BE INTIMIDATED TO TRY THIS

Dark asylumn

Ok I figured out what was going on with the "bad" light for the 5v and 3.3v outputs.   I am an IDIOT!!!!!!! had the tester on battery load check. oh course it was "bad" mut the tester in the correct position and no "bad" light comes on

Andrew

Around here, we refer to that as an ID 10 T error. At least your meter didn't go PHHHHHHHT !!

Your resistor can go on either leg of the LED just use the 5v (red) rail and 1/4W resistor in the range of 180 to 220 ohms. If your ambient light is pretty bright, you may want to use the lower resistance to brighten up the LED.

Glad you got it up and running.

andrew

Dark asylumn

I use the resistors that my led supplier supplies me with. I have just about every color led there is. I dont know their value (different for every color) but they work in the cars so I am good to go there. Thank you for the fast reply

Dark asylumn

Here is the second one Idid its pushing 19a at 12.18 volts under load. Ididnt hook up the 3.3v bc Iran out of posts and waitin for local ratshack to get more in Ibought all their 1/10 resistors 10/10 resistors and all of their binding posts. They keep like 3 packages in stock here of everything kinda sucks for an hour drive and not come home with ALLthe parts you wanted



the 120 mm fan on the top is great to keep your batteries cool

AJsToyz

Andrew,

I'm running an old Dell ps and its @ 11.4 volts no problems but am going to try the 10 ohm resisters to see if it comes up to 12v. I'm looking at some newr supplies that show multiple 12v rails. I'm guessing that these are totally separate and can run the stated amperage per rail?? 12v-1 19a 12v-2 19a 12v-3 19a I should be able to rune three chargers @ 19a each??

If this is the case I can get one of the new PC power supplies, run all three of my chargers with out having three power supplies running. I have some 4mm female bullets I'm using on one charger so I don't have to mod the case.

I love this thread, saved me some money not having to purchase an expensive power supply. With the newer chargers I just set the max draw to 6 amps and the old ps works just fine!

Andrew

You will likely find that the voltage on the 12v rail of your DELL will increase somewhat - I've not seen a supply that did not respond with a higher output. 11.4v is a little low to start, so hitting the 12v target is unlikely. However, a second advantage of the load resistor, particularly on the older supplies, is voltage stability under load - you won't see as much of a voltage drop as the current demands increase.

In response to your comment on running multiple chargers at 19A, that is probably not going to happen. The guidelines were modified to include a 12V2 rail (second 12v source) when the 20 pin Molex MoBo connector could not carry the power demands of the newer motherboards at time. The powersupplies were being beefed up and the processors were pulling more power than ever, but the standard 20 pin connector had a single 12v line - the connector was failing due to overheating. The newly added 4 pin 12v2 connector was rated at 192 watts and would support a 16A load. On some supplies, these are sourced separately, but on most, the 12v source is from the same location on the PSU board. The limiting factor was the current capacity of the connector. On one supply here in my office (counted 11 laying around), the specification placard lists 12v1 @ 18A and 12v2 @ 16A - this is a combined output of 408 watts. But, there is also an entry indicating that 12v1 and 12v2 combined will max at 300 watts or a total of 25A. On the better supplies, the placards will indicate the maximum combined load that the rails will carry, usually significantly below the output calculated by adding each amperage.

Many of the high wattage low dollar PSU's are grossly overrated and will not produce the claimed current. The Intel Design Guidelines are just that, guidelines, and manufacturers are not mandated to follow them. When shopping for a supply, see if it has an image of the spec. placard and if you can read the max combined wattage - I guessing it will run in the neighborhood of 70 to 75%. Translating, you might be able to run 3 chargers at 10 to 12A, assuming that the specs have not been puffed up too much.

Regards,

andrew

AJsToyz

Andrew,

Thanks for clearing that up. I have no problem at the moment just takes a little longer to charge batteries. I found and extra power supply in the basement from a machine I parted out, an Antec True Power 380. This ones rated @ 18A on 12V so I'll be able to put the settings back up a little on my 10s. I think I can set the max. amp draw on my 4s and 10s but not sure about my Triton, I'll check to make sure.

Thanks for the input.

Andy

cummins driver

My Feedback: (31)

I am getting ready to do this myself since i plan to upgrade chargers and batteries soon and will need a power supply.

I heard somewhere that a lighted switch, or an LED alone would be enough load to trick the power supply into turning on. Is this right, or do I need to wire in a resistor? I was planning on wiring in an LED to show when the power was on.

Thanks[8D]

Eric

Edit- I kind of answered my own question by reading at the bottom of the 1st page. I think ill try the LED and if it wont power up, or if I need more voltage, ill stick a resistor in it. Basically though, I just dont like the fact that the resistor produces heat. Ill see what happens. Gotta get a power supply first. Hoping dad can get me one for free at work. I bought the banana jacks and plugs today. Just going to try and run 5 volts and 12 volts so i can test motors, etc and run a charger.

Dark asylumn

my resistors only get up to about 100f degrees so they really arent that bad

cummins driver

My Feedback: (31)

That doesent sound too bad then. Ill probably end up getting one and wiring it in. Ill probably have to in order to get 12+ volts going by what i have read.

Eric

Dark asylumn

I use 2 in series so it splits the load and heat you gotta buy 2 in a pack anyways

cummins driver

My Feedback: (31)

Well, I have finished my 230w power supply up.

I put in two grounds, a 12v hot, and a 5v hot. I wired in two 10ohm, 10w resistors also, and they are in front of the fan for cooling.

It works good. It has its own switch, and I wired in a standard(non LED) light to the 12v side. However, with no load, it is putting out just over 12 volts. Right at 12.1 and 12.2v. When i put my charger on it, the charger works fine, and nothing kicks off, but the voltage goes down to around 11.7v

Is 11.7v too low under load? Its definately lower than I would like. I ran a motor on the 5v side and plugged my charger in before i had the resistors wired up and it was putting out about 12.3 volts, so i know it could still come up some, but im not sure what i should do to get it there, of if i should just leave it alone. I just dont want to damage my charger.

Thanks for any help!

Eric

On Edit- My duratrax Onyx that im currently running on my PS is rated to run at anything from 11-15 volts. And the Accucel 6 charger I am buying is rated to run on anything from 11-17 volts. So, that makes me feel better about the PS putting out 11.7 volts under load, but I still think 12 volts under load would be nice. Let me know what you electronic guru's think[8D]

keredg

plug a 12v tail light on the 5 volt rail and see what you get, upped mine from 12.15 to 12.47v even though i have resistences in aswell

cummins driver

My Feedback: (31)

I think that would help since the voltage is about 12.3 under load when I have a motor running off of the 5 volt side. I just hate to put a bulb in there because of the heat, but I would like to up the voltage a little so i may try it.

Eric

Andrew

In series or in parallel? If in series, wire them in parallel. If already in parallel, wire in a third resistor in parallel - this will increase the load to 3.33 ohms which may help boost your 12 rail and improve stability under load.

andrew

cummins driver

My Feedback: (31)

Im assuming it would be called parallel in this case. I have them both side by side with a hot running into the same end of both of them, and a ground running into the same end of both of them. I think 1 more resistor would get it over 12v. It came up from 10.7v to 12.1 volts without load by adding the 2 resistors. One more might would do the trick.

Also, I have just 1 hot wire that I split to run to the resistors. Is this fine? Same with the ground. Thanks!

Oh, and my sister goes to Murray. Do you teach there?

Eric

keredg

the resisters will probably get hotter as that is how they are supposed to work, heat sink them well. A bulb will create less heat as it converts the energy absobed to light rather than direct heat as the resistors do, the 12v bulb will only be dim on the 5v rail and doesn't create much heat, also works as an on indicator when lit

Andrew

One wire will be fine - if you can heatsink the resistors against the case, it will help keep them cooler than just having them in the airflow.

I do teach at MSU - Dept. of Computer Science. Graduation was today.

andrew

http://web2.murraystate.edu/andy.bat...owersupply.htm

cummins driver

My Feedback: (31)

Thanks, I may add in another resistor then if you think it will help. It'd be nice to have it over 12v at least.

I had been using that link and I knew it was yours, but i just now realized it was on Murray's site. haha

I graduated from EKU today, my sister still has 3 years or so left though. Now I just have to find a job, which is proving to be tough.

Eric

4nn4

Dear collegues also Mr. Andrew of MSU....
I am Vincent who might personally write an email to you then I am sorry for the inconvenience as I am so newbie in this area.
So, it seem again I stumble to read this good site andtherad and get know more about converting PS to DC power supply.
And it's even surprise me the same of Mr. Andrew of MSU also here

Btw,I may explain why I interest to build, this is may different from other who may use for RC/Lab purpose. I am thinking to use it as power source 12VDC of my portable air inflator (which isusually use for emergency air inflator for car's tyre using cigars lighter or directly car's battery 12v power source).

However I may use this air inflator a lot around my home so a 220VAC-12VDC converter is needed. But the current needed to run this inflator around rated 20-30A and as you know it's quite expensive to buy real converter AC-DC who can supply much current.

So if is possible to draw out allthe current from 500W ATX power supply for 12VDC only, if I eliminate all other voltage ?. I just need DCV +12V
The PS label state +12V 10A and I count there is 6 yellow 12V cable avalaible to use

Thank you for your kind advice

Regards,

Andrew

Email reply sent.

andrew

4nn4

dr. Andrew...
Thnak you so much for your email's reply and also for this forum/therad it's very clear information. I may put aside the idea using the PS to power up a mobile air compressor but it's still intriguing me to build this DIY project for other purpose

Regards,

icarus46

Heres a pic of the one I made. They work quite well.