Adding smoke to a new Bachmann J-class

[tucknroll]

Anyone have any experience adding smoke to one of the new Bachmann Spectrum HO N&W J-class locos w/ the Soundtraxx sound decoders? I know most modelers are against smoke, at least in HO due to residue left behind and it not being realistic but this is more for fun than realism and its a small layout so cleaning won't be a huge issue. I've tried to contact Soundtraxx but supposedly the wiring on the decoders for these locos is modified slightly by by Bachmann so the points/functions are different.  I was hoping to not have to wire to the motor leads or something as I would like to be able to turn the smoke on/off. The unit I have is a Seuthe smoke unit designed for plastic locos. Any ideas please let me know. Thanks!

Fred

[richG]

You can use one of the functions, say the tender light which would require another wire. Also hook the other lead to the blue common wire going to the loco light.

Find out what the current draw at 12vdc is for the smoke unit. Then check how much current the decoder can supply for each function.

Rich

[tucknroll]

Thanks for the info. I gave it a try but apparently it didn't have enough current as neither the smoke unit or tender light would come on. I'm not really sure how to test the current though. I've got the Digitrax Super Chief so I'm sure there's a way, I'll just have to look it up. The tender light wires each had a designated spot on the decoder so I ran wires from the smoke unit to those as there were no blues wires anywhere to the engine. Thinking back I could probably have spliced into a front headlight wire but not knowing which was the ground & no way to tell I didn't take a chance. Looking back I should probably have run the wire to the front headlight points on the decoder as the way it would have worked, if it worked would be the smoke only coming on in reverse as that's the only time that light works.

Anyway...If you have any other ideas please let me know. The only other thing I can think of is to run wires to the pickups and install a small switch on the bottom of the tender like what MTH does on their O gauge engines. And for anyone else thinking about trying this...there sin't much room for a smoke unit anyway. The front headlight holder is in the way and it's diecast. I cut some of it off but the top of the smoke unit still sticks out too much. Otheriwse you'll have to cut the whole bracket off and remount the headlight. Let me know if you have any ideas. Thanks!

[richG]

Since the smoke unit is set up for 12 volt DC, use the current scale of a digital voltmeter, to measure tha current being drawn by the smoke unit using a 12 volt DC power supply. If you are working with DCC or even DC, you should have a voltmeter.
There is a chance the decoder cannot supply the current required. I have seen this issue before in a couple other forums. Hopefully you have not wiped out the decoder.

Rich

[ta152h0]

Smoke generator are simply a low resistance short. it doesn't care if the current is DC or AC or DCC. breadboard the smoke unit directly from the output leads of the DCC power source, mine measures 15.8 volts. Breadboarding allows you to experiment with resistor values to cut the voltage prior to installation. Those things get hot so a metal bodied boiler is a must. Essentially you are throwing oil on a hot exhaust pipe. You might want to consider examining the MARKLIN 7226 smoke generator.
oh yeah, to complete the thought, run the leads from the red/black wires feeding the decoder. ( bypass the decoder )