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Yes.airbrush said:so the resistors values for the 1.7 leds on the previous page are still correct then??
You're welcome, I'm glad to help. :lol:thx again for your help
Did you build both circuits?airbrush said:okay...a slight problem...all the LEDS are still on when the pots are turned down....so i need to reduce the value of the 180 resistor for 1.7volt leds and the 910 resistor for the for the 3.3volt leds schematics accordingly??
How much do I need to reduce it?? what do you suggest to try??
How much is their current? Measure the voltage across the 390 ohm resistor and use Ohm's Law.airbrush said:hmm...thats very strange...the orange ones are no where near as bright as the green or white and they are actually rated at a higher brightness than the green LED are :? ...
You never said what is your voltage measurement of the LEDs so we are just guessing that they are 3.3V.the green and white remain on all the time...what would you recommend I change the 910 resistor value to??
audioguru said:Ok, if the green and white LEDs are rated at 3.3V each, then with two in series with a 220 ohm resistor, why do they light with the 6.02V that you measured? The only way to reduce their brightness is to measure their voltage then change the circuit to match.
dont know why they light...so how do i measure the LED individual voltage if they are not correct as they were specified?? :?
You can'simply reduce the value of the 910 ohm resistor to dim the LEDs at minimum pot setting, because then their max brightness will also be reduced. The resistance of the 240 ohm resistor also must be reduced but not as much as the reduction of the value of the 910 ohm resistor.
So how do i keep their max brightness and still have then dim totally off...so is that why my orange ones that dim off are not as bright as they could be?? So you're saying that adjusting the 910 will adjust their min so the dim off and then adjusting the 240 will keep their max brightness?
What is the voltage across the orange LEDs' 390 ohm resistor when the circuit's pot is at the brightest? Also, double check and measure the 390 ohm resistance of the resistor.
Yes, but the resistors affect each other. We need to know the actual operating voltage of the LEDs and their series resistor to recalculate the resistors properly.So how do i keep their max brightness and still have then dim totally off...so is that why my orange ones that dim off are not as bright as they could be?? So you're saying that adjusting the 910 will adjust their min so the dim off and then adjusting the 240 will keep their max brightness?