Fitting suethe smoke generator to HD Flying Scotsman

[Jon-350572]

Hi all,

has anyone fitted a smoke generator to the new HD Flying Scotsman? I’m looking at adding one to my BR version. I’m just wondering, do I need to run two wires from tender to loco? Or can I use the new draw bar?

regards

[ColinB]

Well if you want it under DCC control you have two options, run wires from the tender off the main DCC controller or fit a function decoder in the loco to just control the smoke generator. You give the two decoders the same address and assuming you don't use sound you could make F1 your smoke generator control on the function decoder. The new drawbar only has four connections as far as I can see. What you could do is connect it across the motor so the higher the motor voltage you get more smoke.

[Jon-350572]

Hi Colin,

thank you for your reply.

I already have a sound decoder in it. I’ll look into running a couple of wires across from the tender to loco and use one of the function keys to turn it on and off.

[37lover]

I haven't fitted a smoke generator but have read several posts about them and vaguely recall something about their current demand sometimes can be higher than that provided by the decoder function circuit.

[96RAF]

The normal method is to use the function output (limited to 100mA usually) to pull in a relay and for the relay to carry the smoke unit load if it’s current draw is outwith the decoder limits.

[Jon-350572]

Thank you 37lover and 96RAF. I’m using a zimo 648r sound decoder which I have been told by the seller (digitrains) can handle the generator without a problem.

its just working out where to run the wires.

regards

[P-Henny]

What you could do is connect it across the motor so the higher the motor voltage you get more smoke.

 

 

Personally, I think that is not something anybody should do. Smoke Generators can potentially draw a reasonable amount of current, add that to what the motor draws could exceed the decoder spec. Then the smoke generator heating coil could possibly affect the motor BEMF detection in the decoder and/or affect motor performance.

EDIT: I am assuming that the quoted statement means across the actual motor and not the motor feed output from the second decoder. Particularly as 'Function' decoders as specifically stated don't have a motor feed anyway.

[ColinB]

Yes the Zimo will handle the current, I checked when I fitted one to my West Country. I think the last time I measured the current it was about 120 milliamps it was just over the maximum output of TTS. The interesting part was I measured the current for a 1980s Hornby smoke generator and that was just under the 100 milliamps. Trouble is they were as measured on just two units, others may be higher. A smoke generator I doubt is going to make much effect to the motor current unless you are very near the limit especially as we are talking about a Zimo decoder. I take your point about the back emf though although I am not sure what effect it would actually have in reality. My suggestion was just away of avoiding extra wires to the tender. I must admit if it was me I would look up the cost of a LaisDCC decoder (last one I bought was £13.99) and use it as a function decoder in the loco itself. It is an A4 so there is plenty of room. NOrmally I avoid seuthe units like the plague as they distort loco bodies but in a HD case it is probably one of the few locos where it won't.

[Jon-350572]

Thank you all for your replies.

i shall do some more research.

regards