I have been tasked with designing a "spy kids"-like console with radar images, flashing lights, working switches, etc. I have the pc parts figured out, but am a novice with electronics - last time I built a circuit board was as a kid.

Wanting to setup a few simple flashing LED panels with off\on switches. Have found a few places that sell 12V flashing LEDs.

http://www.vellemanusa.com/us/enu/pr...iew/?id=349956

http://www.partsexpress.com/pe/showd...number=079-175

My first question is can I use an old 12V power supply scrapped from an old wireless phone base (or one I could pick up at radio shack) to power a bunch of these things? I was planning on cutting the adapter plug off and wiring it straight into some of these with an on\off switch. If that would work - would I wire them in parallel or series? How many do you think could be wired off of 1 standard power supply?

Any advice is appreciated! (Also, if anyone has any simple ideas to add some "coolness" to such a console - that would be awesome too!)

Thanks!

Glen M

 

By Power supply do you mean a wallwart aka AC Adapter?
If so, then yes you could use it.

Put the LED's in parrellel, also observe correct polarity.

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Thanks! Yes - it is a wall AC adapter. 12V/1500mA. How many 12V LEDs could I conceivably run off of one of these? And could I run multiple parallel circuits off of it? For instance - 3-4 LED panels with x LEDs each and an off\on switch for each panel - each running parallel off the one AC adapter. Is that possible?

Thanks!

Glen M

 

to answer that you would need to know how many mA each LED needs.

most red LEDs need 20mA, but im not too sure about these, because they run at a much higher voltage and may have a flashing circuit in the casing.

asuming they do run at 20mA you should be able to run 75, although i wouldnt trust my calculations.

yes, you could run multiple circuits off it, as long as you dont exceede the maximum ratings of the supply.

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hi Glen,

Have a look at this link.
http://www.kpsec.freeuk.com/components/led.htm

You should not connect LED's directly in parallel, each 'parallel' LED requires it own resistor.

As you have a 12Vdc psu, I would suggest series connection of the LED's would be the most efficient.

Eric

 

if you wired 12 volt led's in series, wouldn't you have to have a higher voltage? if you wired 4 led's in series on 12 volts, each led would see 3 volts, but if you had say 7, each led would see 1.7 volts, which isn't enough for yellow's, blues, whites, greens and all the others except for red. right????

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hi things,
If you look at the link I posted for Glen, you will see the majority, if not all common LED types fall within the 1.5v thru 5v voltage band.

Eric

 

You can get simple multicolour flashing leds that would look impressive, some cycle through red,green, blue quickly and others slowly blend the colours.
Have a search on ebay, usually China based suppliers have them in various quantities and cheap.

 

Hi picasm,
The colour cyclic LED's are called 'rainbow' LED's, if you want to refine the search.

Eric

EDIT:
http://www.bit-tech.net/modding/2002.../rainbow_led/1

http://www.goldmine-elec-products.co...?number=G13897

 

I'm looking at using the 12V flashing LEDs from here:

http://www.partsexpress.com/pe/showd...number=079-175

So from what I understand if I put several of them in series I would require more than 12V power. But to put them in parallel each LED would require a resistor? That sounds like the way to go I suppose. What kind of resisters would I need?

Thanks all!

Glen M

 

Just hook them up in parallel to a 12VDC wall wart, 500ma is common and should be enough for a couple of dozen of those flashing LEDs.

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Hi Glen,
I don't know how many flashing LED's you are planning, but the flashers in the link will be an expensive way to do the project if you use more than one or two.
It would be possible using a simple pulse generator [555 or equiv] with a couple of logic ic's, using budget LED's to give flashing and LED sequencing.

Eric
EDIT: using the flasher in your link, its already got internal resistors/etc, so these parallel flashers dont need resistors.
Look here:
http://www.glowsticks.co.uk/acatalog...NOVELTIES.html