Backlighting and 12V Power Supplies.

[Holclo]

I am at the stage where I am backlighting my panels using LED strips and considering Cold Cathode Tubes. Now on E-buyer I can purchase a 500W power supply with 4 Molex connectors for about £13. Sounds good to me but as I do not really understand electronics is this a good idea and the way to go? At the moment I am using one 12v adaptor to run the 24LED strip that I am using but I need lots more!!
Bill

[Trevor Hale]

Hey there.

If I were you I would bank on 45 - 50mA per led X 24 Led's = aprox 1 - 1.2 Amps per strip. a 500W power supply is probably capable of supplying around15 - 20 or so Amps at 12V.

Do you think that would meet your requirements?

Best regards,

Trev

[ian@737ng.co.uk]

hello captain.....
trevor is right. i dont have the patience to sit there soldering 100's of led's and resistors, so i went down a different route. i used 12v MES bulbs instead on an ATX 500w power supply. i ended up with 12 to backlight my overhead, so for your purpose, i dont think you will have any issues.
attached is a picture of the MES bulbs when i was wiring them into my old overhead. led's draw so much less power than a bulb, so i guess you will not have any issues.
have a great day .... ian

[Holclo]

Thank you guys. Just to prove I am a real beginner when I get this power supply which has 4 molex connectors does this mean I can only attach 4 LED strips or 4 Cold Cathobe Tubes. Can I purchase "molex" connectors to attach to the LED wires so that I can connect it to the power supply. It is obvious that I have never even seen a PSU!!
Bill

[mpl330]

Bill,

Its possible to buy molex Y splitters that take one molex lead and this 'splits' it to give you 2.

I've ordered some cold cathode tubes myself this week for back lighting (also from E-buyer and only just over 2 pounds for 2 ) - I'll update to let you know what connections they have...

Regards
Mike

[Holclo]

Thanks Mike. I will be away from my computer for most of next week but will look forward to your observations. I think cold catobe from ebuyer come with molex connectors and a switch. I am thinking of ordering red. What have you ordered? Very interested to hear your opinions. The postage (courier) is very expensive. £8.90 to deliver a £4 order - that is why I am also going to purchase the PSU at the same time - postage only goes up to£9+.
Bill

[Trevor Hale]

Thank you guys. Just to prove I am a real beginner when I get this power supply which has 4 molex connectors does this mean I can only attach 4 LED strips or 4 Cold Cathobe Tubes. Can I purchase "molex" connectors to attach to the LED wires so that I can connect it to the power supply. It is obvious that I have never even seen a PSU!!
Bill

Hi Bill, actually all those molex connectors are wired in parallel inside the psu. Keep in mind in order to get the psu to power up I beleive you will have to find the Green wire and connect it to ground. (a black wire). Take one of the large molex connectors and cut the Black and Yellow wire off of the molex. (The Black next to the yellow)

Wire all your strips to the black and yellow and use solder or wirenuts to secure them.

Don't waste your time messing with the molex connectors.

Best regards,

Trev

[mpl330]

Trev,

I was thinking about cutting the molex connectors off and then connecting 2 or 3 cathodes (via a switch) to one pair of cables (+ve & -ve) from where i've cut it off - shouldnt be any issues doing that should there?

Thanks
Mike

[Trevor Hale]

Nope, No problems at all.. If I understand you right

[Holclo]

Ah right I think I need to clarify and possibly Trev will be answering Mikes points as well. What I was thinking was to use the new PSU outside the computer and simply for providing 12v for the backlighting and nothing else. This would be to save having a number of small 240v to 12v adaptors cluttering up my power extensions (already have about 12 different plugs (monitors, printers, throttles usb ports etc)
Bill