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Main => Everything Else => Topic started by: rmusick on December 01, 2011, 04:11:01 pm

Title: Where can I find Blue LEDs?
Post by: rmusick on December 01, 2011, 04:11:01 pm
not sure if this should go here but...

Hey I i need some advice on where to shop.
I am wanting to do the something done here:
http://forum.arcadecontrols.com/index.php?topic=88912.msg971849#msg971849 (http://forum.arcadecontrols.com/index.php?topic=88912.msg971849#msg971849)

Only I want to use blue LEDs.  I was thinking of getting a strand of 35 LED blue Christmas lights and chaining them up, but all that is sold here is either 35 all white or 35 mulicolor.
Ideas?
Title: Re: Where can I find Blue LEDs?
Post by: Nephasth on December 01, 2011, 05:16:06 pm
Ebay. Sellers from China sell them really cheap with free resistors.
Title: Re: Where can I find Blue LEDs?
Post by: saint on December 01, 2011, 06:02:16 pm
http://www.superbrightleds.com/cat/component-leds/filter/Color,Blue,3,14: (http://www.superbrightleds.com/cat/component-leds/filter/Color,Blue,3,14:)
Title: Re: Where can I find Blue LEDs?
Post by: DCsegaDH on December 04, 2011, 04:20:39 pm
Ebay, I got 100 for about $5 with free shipping.
Title: Re: Where can I find Blue LEDs?
Post by: dextercf on December 04, 2011, 04:59:42 pm
I got a bag of 600 blue, blinking LEDs with (the mentioned earlier) free resistors..
Those china guys on ebay is practicly giving them away.. :P
Title: Re: Where can I find Blue LEDs?
Post by: rmusick on December 05, 2011, 11:18:07 am
Thats probably my best best to Ebay it.. Man I have spent alot of money on their lately  :dunno
Title: Re: Where can I find Blue LEDs?
Post by: rmusick on January 03, 2012, 10:19:02 am
Well, I come with the best solution yet... Well from what I gather the best.  I bout a pack of 35 Blue LEDs at an after Christmas sale.  They are perfect, only one problem.  I was under the assumption that each of the LEDs had a resistor and diode in the housing, bein that it was AC in and there was an AC out on the tail of the string,  Assuming that 120V AC goes through the entire line.  My Logic is flawed.  I cut off one of the LEDs and wired it into 12v DC.  It went up in Smoke.. :(  I guess my question should be this,  Can anyone tell me what Resistor I will need to drop 12v AC down to power an LED?
Title: Re: Where can I find Blue LEDs?
Post by: saint on January 03, 2012, 10:25:07 am
Well, I come with the best solution yet... Well from what I gather the best.  I bout a pack of 35 Blue LEDs at an after Christmas sale.  They are perfect, only one problem.  I was under the assumption that each of the LEDs had a resistor and diode in the housing, bein that it was AC in and there was an AC out on the tail of the string,  Assuming that 120V AC goes through the entire line.  My Logic is flawed.  I cut off one of the LEDs and wired it into 12v DC.  It went up in Smoke.. :(  I guess my question should be this,  Can anyone tell me what Resistor I will need to drop 12v AC down to power an LED?

Depends on the specs on the LED. http://ledcalc.com/ (http://ledcalc.com/) is your friend, makes it really easy. For instance, if it's a 3.3V, 20Amp LED, you'd want a 470 Ohm 1/4 watt resistor attached to the positive (longer) leg of the LED says the site. ledcalc.com makes it really easy to configure varying numbers of resistors in various configurations.
Title: Re: Where can I find Blue LEDs?
Post by: drventure on January 03, 2012, 12:10:42 pm
If you get leds from some unknown place and are not sure of their specs, you can always do this.

Grab a pack of misc resistors from radio shack. They usually range from 1ohm all the way up to 100k ohm

Start at about 10k, and work your way down from there. At 10k ohm, most 3-12vdc leds won't light, but you won't blow them either.

Starting around 600 to 1k ohm, they'll start lighting but be very dim.

Once it's reasonably bright, you should be good. Go too low with the resistor though, and you'll blow the LED.

Alternately, use a Voltmeter to measure the forward voltage of the LED, and then use calculate saint mentioned. It's esp handy if you have several LEDs you want to light simultaneously.

Title: Re: Where can I find Blue LEDs?
Post by: rmusick on January 03, 2012, 12:45:39 pm
Thanks for all of your suggestions,  Will try them out this weekend.. Will let you know how it turns out.