Miniatronics bulbs on 3mm led source

wire the bulbs in series. To calculate a resistor for parallel you need the input voltage. I would guess 100 ohm,half watt added resistor. This assumes 3.2 volts input or a series resistor already in place to the LED from the power source.

Dale H

Does the headlight LED have a resistor in line or is it just plugged into the decoder?

Normally LED only use 20-30ma of current and operate about at 3VDC.  So the question is one of rating of the decoder light circuit.  What current it can handle.

If you put 2 bulbs in parallel you would be drawing 30ma each or 60ma total at 1.5V.

If you put them in series as Dale says you would be in better shape with an equivalent 3V drop and current probably down around 30ma.  Which should work.  G

Standard LED's, that is virtually all the consumer types, are rated at 20ma maximum current.  If the decoder output is current limited, they may not be all that bright, but surely you'll want them in series.

Thanks for the input, I intend to do this on the new 3rd rail F7's. Don't have them with me right now (international shipping), but I suppose the come wired directly from the decoder. I'll see when I get them. Series seems like the way to go. I'll report back when I get them. Thanks again.