Electronics Power supply/battery charger,

Hi Guys,Maybe someone can help me out.My other hobby is radio control trucks (the fast ones), now, i need to buy a good battery charger, the type i am going to buy needs a 12volt power supply to run it, i can buy a mains powered power supply from my local modelshop which converts to 12 volt, the thing is this costs £40 which i don't want to spend. So my question is can i use a PC power supply, i have a spare 250w power supply and i was going to fit an appropriate plug to the 12volt molex connector and use it to run the new battery charger, can i do this or is there other issues i should be aware of. Cheers

 

It will work no problem, its what my brother used when we did 1/10th off road for ~9 years.

'doc

 

Well an easy way to check is see what that psu can give on its 12V rail and compare it to your chosen charging current. Now its been a while since I've been in the hobby but the highest any of my chargers would go was 9.5A, which should be fine on most psu's AFAIK.

 

Hi Guys, Thanks for the replys, It would be great if someone could check this link out for me, it is a short spec list of the charger i would be running, Thank you.
http://www.sussex-model-centre.co.uk/Pro-Peak_Prodigy-2250.htm

 

Trust me, it will be more then enough.


'doc

 

You may need a dummy load on the 5V line to keep the psu on (and give accurate 12V regulation) at low charging currents. A 6V 5W bulb would do the trick, or a 4.7 ohm 10W resistor.

Or it could be a "feature", where the psu automatically trips off when you disconnect the battery on charge.

 

I had thought about plugging in an old floppy drive, would that be ok,

 

Not really, a floppy drive probably wouldn't draw enough current to stabilise the PSU properly. Best just stick with a resistor of about 5 ohms like cpemma said. Note that it will get a little bit warm though... Other than that I cannot see any problem with using a PSU like that - I've used old PSU's to drive all sorts of things, from CCTV systems to small TV sets. (It was an old caravan TV that only ran on 12 Volts)

Edit: If you're in the UK, Maplin sell 10 Watt 4.7R resistors like the ones you need for just 19p each. (Order code H4K7)

 

Hi Guys, So if i go and buy the resistor you advise where exactly do i put it (no remarks please) complete noob where electronics is concerned, also when you say resistor do you mean the tiny little ones that are used with LEDs. Cheers.

 

Put the resistor from any red wire (+5V) to any black wire (Ground).

This resistor does will be a little bigger than those little resistors you use for LEDs. Those resistors are only 1/4 Watt, the 10 Watt one you need will most likely be white ceramic and be a couple inches long and a half inch square.

 

Hi Guys, before i go ahead and connect everything together could someone double check via the photo's below if everything is fine to use, also going of the specs below do i still need the resistor that has been mentioned, Thanks Guys,


The photo below is the spec lable on the PSU.



The photo's below are the spec of the charger.

 

Everything looks cool. As for the resistor... you'll just have to try it out. Some PSU's need some kind of a load on the 5V rail to stabilize them. But the half dozen or so PSU's I've turned on with no load, all has been well, so just fire it up and check the voltage on the 12V rail. If things seem to be acting up a bit then try the resistor, but I have a feeling you wont need it.

 

Thanks biff, just to double check, red+black=5v and yellow+black=12v is this correct thanks again.

 

Correctomundo!

 

Thanks again, much appreciated.