Can I use 560 Ohm 1/2/ watt resistors, if the directions call for 560 Ohm 1/4 watt resistors? I am wiring 1.5 volt mini lamps to a soundtrax decoder in my HO brass 2-6-6-2. The issue is that I have the 1/2 watt resistors, and am having trouble finding 1/4 watt.
One of you electronics guys must have the answer to this.
yes…you can use either the 1/4 watt or the 1/2 watt…the only difference is the size of the resistor…i’ve used both on many different circuits and have had no trouble at all with heat dissipation issues with either of them…chuck
As a general rule, you can substitute a higher wattage resistor for a smaller one, but not the other way around. As CW pointed out, the size may be the only problem, but if you have room in the loco, it won’t be.
Art, remember that the resistor can be anywhere in the wire running from the decoder to the bulb, so there is sure to be space somewhere in that path. I like to put some heat shrink tube over the join between wire and reistor, to ensure that stray metal does not short.
Ohm’s law… P(ower) = current squared (light bulb rating) times resistance. Use the power rating of the bulb, for example 30mA (0.03 amps) times 30mA times 560 ohms (resistance) = 1/2 watt. The Half watt is actually what you need.
As Tom explained you can go with a higher wattage just never a lower wattage.