CHEF-UK

Re: Power supply for RC use


I need some help, I have read numerous pages on this site and elsewhere but I still have a problem.

I am using a ASTEC 200W computer power supply which says on it 12V @ 8A

I am wanting this unit to power my triton charger.

The PSU does not say AT or ATX,

I have managed to bridge the unit so it powers on as there is no actual power switch.

I have found the + 5V +12V, Common wires etc.

The problem is, I have put a load on the 5V line. I have tried 1 10ohm x 10 watt resistor and I have also tried 2 as well. I get nearly 12V on the 12V outlet side, but as SOON as I connect my triton the 12V line goes down to 3.46V. I am thinking that maybe the TRITON take a Boost at start up and my PSU is not capable of delivering that. What can I do? Is this power supply not adequate for the job or what. Just cannot seem to get the triton to power up. As soon as I connect it to the 12V output the PSU does NOT shut down, it just lowers that voltage.

Help, as I have read so much on here, Do I Need a capacitor and if so which one and how do you wire it etc. In electrics, I am no expert at all! So layman terms please �


Keith, in windy UK

CoosBayLumber

My Feedback: (1)

Computer power supply current ratings are deceiving. So many times, the noted wattage relates to a 120/220VAC INPUT rating and not to a total output rating. Just do the math, Amperes times volts equals watts. The output rating so often is based on the primary windings of the transformer, as it is easier to measure it there.

The output rating is maximum peak power, but combined over the 12+, the 5+ and the 3+ output ratings. That peak power rating is not continuous, and usually 2/3rds is the expected maximum on over one minute. Many computers only need the boost in juice to get a silent hard drive spinning, which takes just a few seconds. Usually no one of the leads will give the rated power output, but as a group they will get near it. If you have a voltmeter handy measure the current at each of the P.S. output lines and see if they are all down some when you try and draw maximum. If the 12+ lines read less than 11 volts, then there are internal problems with the power supply.

One thing, if this is not a new power supply, quite often the ratings are then bad for one of the leads. Computer power supplies tend to loose some voltage with use, until they cannot fire off the 12+ for the hard drives. A hard drive will run on 10 volts, but it will not start spinning unless there is a full 12 volts to boost it into motion. This does not happen to just one lead, but all of them too.

Stick with the earlier AT style computer power supplies, as they did not incorporate the electronic on/off switch that the later ones did, and thus compounding your problems. The later power supplies had a big 20 pin connector, of which you had to short out a pair or so of wires in order for it to turn on.

Wm.


Wm.

ballgunner

My Feedback: (1)

Best AC/DC power supply I've found yet is from AstroFlight. About 75 bucks from Hobby Lobby.

Ed Smith

I have found that whenever I ask questions of computer geeks, I get the glassy eyed stare and they bombard me with bafflegab. So, do yourself a favour and buy a 12v motor cycle battery with a wall charger. You now have a portabe, rechargeable power supply.

Ed S

iowanspctr

I built one using two 10 ohm 10 watt RadioShack resistors paralled on the 5 volt to ground side. Works just fine with my Triton! Gives me just short of 12 volts and holds up well.

msu68stang

My Feedback: (7)

Here is the power supply you need. At $20 it's cheaper than any hobby power supply. All you have to do is wire in a power cord. A computer power cord should do. I have one and I have never had a problem with it.

[link=http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=36323&item=3839543 254&rd=1]Cosel Power Supply[/link]

Chris

Walleye

I have built about 6 of the power supplies with 3 different types. The most common problem most people have is forget to move the selector switch to 115 volts instead of 230 volts which will cause the exact problem you have. The switch is red and located next to the power cord. Hope this helps. I also used 10 ohm in parallel down to 2 ohm 25 watts. the smaller the ohms the more power it seems to have under load. Don't forget the heat 25 watts will produce.
Jerry Wallis

DABradbury

Check out [link=http://www.club-chat.co.uk]Club-chat[/link]. They have a good artice on using a computer power supply for powering a charger. I converted one a while back for use with my Supernova that is still going strong. Any problems finding it drop me a line and I will get a linksorted out..

Dave

branded

My Feedback: (9)

Have you connected the 12 volt sense leads to the 12 volt output wires? If you don't know which is which then you must connect all the yellow wires together (whether you're using them or not) as well as all the black wires. If not then your supply will kich offline.........

4*60

My Feedback: (41)

You guys resurrected this from Sept 2004. The PS was probably thrown away by now.