I'm using miniatronics "Grain of Dust" lights with 163 decoders, WHAT VALUE RESISTOR should I be using? I need to use the Grain of Dust size bulbs with my steam engines. I mount them in back of an MV Lens installed in a brass headlight casting. Is 800 ohms too much? Will using a 1/2 watt resistor instead of a 1/4 watt resistor get me anything?