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2 Responses to LED, Resistor, DC and DCC
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The vast majority of led’s only require around 2Volts with approx 10 ma through them. If you want to operate on eg. 16-18 volts which is typical for digital layouts you need to ‘drop’ 14 to 16 volts. ie. 14v divided by 10 ma is a resistor of 1400 ohms, say 1500 as you cant get all values. for 16v increase ressistance slightly to eg 1800 (the next value available! Check actual voltage and current for the Leds you use but the maths is the same.
Colin
Tim, the most used LEDs in H.O. engines are the 3mm and the 5mm, the resisters can vary, as to how bright you want the LEDs to be. a 1K1000ohm1/4watt resister works fine with 10 to 14 volts on the rails. If using more than standard 14 volts use 1/2 watt 1K resister. If space is close a 1.5ohm 1/8 watt resister will work. This is for DCC, always remember, polarity must be observed with LEDs, keep your plus and minus straight, the longer arm on LEDs are +…Hope this helps.