Using a computer power source to control LEDs, et al..?

[SDHLaw1701]

Hey,
I kind of have what might seem as a silly question. I have heard of others using a computer power supply to power LEDs and other components in a model, given all the varrious wires eminating from the computer power supply how do you properly hook up the LEDs to the power supply with out destroying the LEDs and other lighting components (i.e. flasher boards..etc). Thanks
SDHLaw1701

[macfrank]

Hey,
I kind of have what might seem as a silly question. I have heard of others using a computer power supply to power LEDs and other components in a model, given all the varrious wires eminating from the computer power supply how do you properly hook up the LEDs to the power supply with out destroying the LEDs and other lighting components (i.e. flasher boards..etc). Thanks
SDHLaw1701

Using a PC power supply to light up some LEDs is overkill. PC power supplies tend to be bulky and have fans. Most modern supplies also require a "power good" signal from the motherboard which you'll have to supply. Also, some power supplies require a current load before they start operating properly. A fully stocked PC mother board is a load. For or five LEDs are not.

[en'til Zog]

Go to "The Realm of Zog" and look up 'Wall Warts'. The little blocks you plug into the walls to power clocks & such. Small, cheap, available.

[Madman Lighting]

Ditto what Zog said. You might want to get a *regulated* wort so the output voltage is smoother and ripple free. If you want to spend about $15, goto Digi key or Mouser and buy a regulated switch mode wall wort. Very compact, very efficient.

-John C.

[fokkerpilot]

Using a PC power supply to light up some LEDs is overkill. PC power supplies tend to be bulky and have fans. Most modern supplies also require a "power good" signal from the motherboard which you'll have to supply. Also, some power supplies require a current load before they start operating properly. A fully stocked PC mother board is a load. For or five LEDs are not.

Overkill. LOL ok, On the 1:350th it's worth it. PC power supplies have fans and rightly so because I wouldn't want a supply like that in my base unit with out some method of cooling. The current load you speak of is easily dubbed by inserting a jumper allowing the power supply to operate with an on/off switch. I strongly suggest the use of one on a model this big with the large number of LEDs involved when considering the total miiliamps. Radio Shack AC power adapters will be taxed to their limits and will eventually fail due to heat buildup.

Now for the smaller kits with, lets say, 20 LED's, then the little wall adapters would be fine and yes, a Computer power pack would be overkill. But not with the 1:350th.

[Madman Lighting]

I just looked at your 1/350th Enterprise, thats really nice work on your part. I've got one of those and its bloody HUGE.

How many LEDs did you use for yours? I'm guessing at least 30, or as many as 50.

I do have to disagree with you about choice of power supply, you dont need a PC power supply, even for that. Each LED draws about 20mA, even with 50LEDs, thats still only 1000mA, or just 1 amp and large wall worts are quite capable of those loads. The newer switch mode worts can do it, Mouser sells them:

http://www.mouser.com/catalog/625/1564.pdf

Nice model work.

-John C.

[fokkerpilot]

Thanks Madman. If I recall there were 68 LEDs total in this puppy. 2 circuit boards run off 12v for the flasher and photons. There's no offense taken to using wall adapters. I just have a slew of desktop computer power packs in the shop. I figured that since I had a fairly large base then why not use a CPU power supply; especially since I could tap the 12v and 3.3v side of it. The fan in this one runs quietly too.

The other good thing about this base is that the top will lift off just high enough to replace the power pack should it ever decide to go on vacation.

Off topic (sort of) but the idea for the base came up when I wasn't compfortable with the orginal design supporting the ship. The idea of the clear rods (martini stirrers) to support the saucer was pretty tacky on behalf of PL. The base they supply is nice but not big enough in my book.
This base I had ordered (custom built) has venting in the front and an exhaust port in the rear to give the power supply adequate airflow.

For those using just the original base, then a wall adapter would be good. My only word of caution is add the total Ma's and make sure that the wall adapter being purchased is rated at least 15% higher that the total Ma's from the build. Otherwise the unit will eventually heat up being pushed to it's limits. And while I'm on the topic of the Wall Adapter, those who need to use resistors to drop down to 3.3volts (for the sake of argument) and are concerned about heat build up may want to consider leaving a window or two open just to allow some airflow within the model. It wouldn't hurt.

[Sparky]

I 've got some pc power supplies laying around too. Found some articles on using them to power all sorts of things, like HAM radios. I think I even found an article on making one into variable power supply. They are well regulated since any fluctuation in the CPU power rail translates to the OS locking up or other un correctable bugs in what ever is running.

I didn’t think that modern PC power supplies required loading to work correctly.

[SDHLaw1701]

Thanks for all the advice. I agree with Fuzzy and thats why I want to use a computer power supply. My question is still do I have to be concerned with all the hook up wires comming out of the supply or do I just use the fan (fo example) wire to attach to the main power wires comming out of the enterprise? Thanks

[Sparky]