Light wiring

[Tylerf]

Hi anyone that knows about electronics,
I can't seem to remember some simple wiring logic but I'm trying to add 1.5V bulbs to a locomotive and I need to attach half of the leads to a common pad on the decoder then the other wires go to seperate function pads. So my question is that 1 the common pad gives 12-14v that needs a resistor wired in between the pad and the bulb leads so can I use 1 resistor between there or do I need seperate resistors for each lead attached to the pad. Any help would be much appriciated.
Tyler 

[richG]

It should be one resistor for each light or LED. Here is a link to this subject. Save the link to this site. Marcus has a lot of good DCC information. One resistor for two or more bulbs is not recommended unless you are electronics savvy. and even then, I would never do that. A few people do use that method.


http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm

Rich

[Tylerf]

Thanks very much. That site definetly has everything I need to know, now I guess I have to get some resistors.

[jward]

the resistor needed would be determined by the current you want to flow through the light bulb. what is the current rating of the bulb? how about the light function of the decoder? the lowest number of the two will be the determining factor.....

the appropriate formula is ohm's law,
basically voltage = resistance (ohms) x current (amps)
the voltage you would use would be the decoder output minus the bulb voltage.
current rating was covered above.

ohm's law transposed to determine resistance thus becomes:
voltage divided by current = resistance.