djsfantasi
Member
I've read that you should use a resistor with a wattage rating that is 20% greater than the load. Then, I've read double the wattage... Which is correct? I'd normally go for double, but when price and size are a concern, I question it and go for the 20% overhead.
Specifically, as part of a 7 segment display module, which eses 2 LEDs in series for a total Vf of 4VDC and running it at 25mA. My calculations call for a 330Ω resistor. The power through it is 0.193W. No heavy duty switching - either on or off. Is a 1/4W 330Ω resistor ok? And why? 0.194 is 77.6%, under the 80% (20% greater than required) mark.
Thanks,
dj
Specifically, as part of a 7 segment display module, which eses 2 LEDs in series for a total Vf of 4VDC and running it at 25mA. My calculations call for a 330Ω resistor. The power through it is 0.193W. No heavy duty switching - either on or off. Is a 1/4W 330Ω resistor ok? And why? 0.194 is 77.6%, under the 80% (20% greater than required) mark.
Thanks,
dj