2006 Wing, 1989 Wing, Past: Honda Elite, Suzuki 450, Honda VT500, 84Wing
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THEORY BEHIND THE RESISTORS:
Here's why the cruise and fuel lights stay on when using LEDS.
In those circuits there is some leakage current through the lamps. Incandescent lamps will not glow because the current is very low, too low to light the filament and the cold filaments act like a short circuit.
The LEDS will emit light once their threshold voltage, anywhere from 1.2-3.7 volts depending on color, is exceeded and because they are efficient they can emit enough light to be deceptively on.
The resistor in parallel with the LEDS bleeds the leakage current around the led so that the voltage across the resistor is less than the threshold voltage to turn on the LED. When the LED/resistor sees the full 12 volts the LED lights and the resistor is for all intents and purposes irrelevant.
The value of the resistor is found by experiment. It needs to be small enough to make the voltage across the led to be lower than the threshold. But the smaller the resistance is the more current it will carry when it gets full voltage to light it and then it gets hotter. So the highest resistance that will extinguish the light with the running voltage at it's max it the value you want because it will keep the heat down when the full running voltage is on it.
The values mentioned here work. Why different? Different leakage current.
The power rating of the resistors has to be high enough to not burn out with 12 volts across it. Power = Voltage squared/Resistance. Example for 470 ohm resistor: Using 14.2 volts as the running voltage 14.2 X 14.2 = 201.64 then 201.64/470 ohms =.429 watts 1/2 watt covers it especially if it can get ventilation. 201.64/1000 ohms= .201 watts so 1/4 watt is enough. You can always go up in wattage rating.
THEORY BEHIND THE RESISTORS:
Here's why the cruise and fuel lights stay on when using LEDS.
In those circuits there is some leakage current through the lamps. Incandescent lamps will not glow because the current is very low, too low to light the filament and the cold filaments act like a short circuit.
The LEDS will emit light once their threshold voltage, anywhere from 1.2-3.7 volts depending on color, is exceeded and because they are efficient they can emit enough light to be deceptively on.
The resistor in parallel with the LEDS bleeds the leakage current around the led so that the voltage across the resistor is less than the threshold voltage to turn on the LED. When the LED/resistor sees the full 12 volts the LED lights and the resistor is for all intents and purposes irrelevant.
The value of the resistor is found by experiment. It needs to be small enough to make the voltage across the led to be lower than the threshold. But the smaller the resistance is the more current it will carry when it gets full voltage to light it and then it gets hotter. So the highest resistance that will extinguish the light with the running voltage at it's max it the value you want because it will keep the heat down when the full running voltage is on it.
The values mentioned here work. Why different? Different leakage current.
The power rating of the resistors has to be high enough to not burn out with 12 volts across it. Power = Voltage squared/Resistance. Example for 470 ohm resistor: Using 14.2 volts as the running voltage 14.2 X 14.2 = 201.64 then 201.64/470 ohms =.429 watts 1/2 watt covers it especially if it can get ventilation. 201.64/1000 ohms= .201 watts so 1/4 watt is enough. You can always go up in wattage rating.
