I have a DCC with sound Bachmann ho SD70ACe that has LED headlights and I want to add LED ditchlights, can I wire them together so they all come on and go off at the same time?
sure, you can wire them together, but you will lose the special effects ditchlights can have .. do you have two spare function outputs that you could dedicate to the ditchlights ??
Check the manual to see if the decoder board has extra solder pads for function outputs. Some later run models look to have functional ditch lights, so unless they got a new board design, you could install them too. If there is no way to separate them from the headlight circuit, just make sure that each LED gets its own resistor.
There is not additional functions on the PC board but there is a small PC board for the lights on the new shell but no outlet to feed that plug from the original board. The original board is in a Bachmann model 66004 and the new shell is a model 66008 with ditchlights installed and wired with the headlights to a separate small board. There is no resistors on this small board.
There is no manual with the Bachmann loco a quick guide only,I have inquired to Bachmann for info on the board for the model 66008 but have not heard anything back. I have checked their parts bin but it is not available, the model 66004 is available but not the 66008.
I just heard back from Bachmann and they are are not and will not stock the 66008 sound board so I hope I hear bacj from Soundtrax the maker of the sound board.
I also have heard back from Soundtrax and there is no part # for the sound board for the Bachmann 66008.
Ido not see any resistors on the headlights front or back so I am assuming the resistors are on the mother board.
Test out the ditch lights before you put the shell on. Wiring LEDs in parallel with only one resistor total is a bit unconventional, usually it is safer to have one resistor for each LED in series. You may have to put additional resistors on the ditch lights, but test it out first. If the voltage and current is low enough, they should be fine. If they look too bright or burn out, add a resistor to protect them.
Wiring LEDs in parallel is not a good idea because each LED has a semiconductor in it with a junction that emits light when the correct voltage is apples across the junction. The problem is that every color has a different voltage and even LEDs with the same color can have slight differences in their voltage. The result is that all the current will flow through one or two LEDs and potentially burn them out. In addition, the brightness will be different for different LEDs. You however can wire LEDs in series with one resistor with a value calculated taking into account the voltage drop across each LED in series.
