Author Topic: Question about LEDs  (Read 3867 times)

Blatant

Question about LEDs
« on: May 08, 2011, 09:45:41 AM »
Hey guys I recently bought a bulk pack of mixed LEDs online. I've no idea about the stats of them, so using a multimeter, is there any way to tell what sort of resistors I will need for a 9v source?
I get the online calculators, but you need to know amperage etc.

cheers

arma61

Re: Question about LEDs
« Reply #1 on: May 08, 2011, 09:53:26 AM »

an easy way it this

a pot connected this way, when you find the LED intensity you want misure the pot value and add the res value, that's your LED's resistor.

         ~200R         10k lin         LED
+9V----/\/\/\--------/\/\/\/\--------  -!>|----   -9
                           |_____|

Ciao

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Blatant

Re: Question about LEDs
« Reply #2 on: May 08, 2011, 06:49:02 PM »
cool, why do you need the 200r in front?
is there a way to test its maximum before blowing?
cheers

deadastronaut

Re: Question about LEDs
« Reply #3 on: May 08, 2011, 09:28:37 PM »
cool, why do you need the 200r in front?
is there a way to test its maximum before blowing?
cheers

if the 200r wasnt there , when you turned the pot fully it would blow it...you must have a resistor on any led...

try a 4.7k resistor on its own with the led..and work your way down to 200r......and you'll see the difference in 'brightness as the resistance changes... ;)
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