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Where can I find Blue LEDs?
rmusick:
Thats probably my best best to Ebay it.. Man I have spent alot of money on their lately :dunno
rmusick:
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?
saint:
--- Quote from: 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?
--- End quote ---
Depends on the specs on the LED. 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.
drventure:
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.
rmusick:
Thanks for all of your suggestions, Will try them out this weekend.. Will let you know how it turns out.
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