DCC Decoder for control of Smoke

There are three obvious ways to wire the smoke unit:

- direct across the track contacts. (uncontrolled and full power all the time)

- direct across the motor. (steam output in proportion to motor speed, but with a major drop-off at slower speeds)

- use a low current relay, switched by an auxilliary output, to control the smoke unit. (the power to the smoke unit can come from track or motor terminals.

The major factors to be considered are the current draws of the individual components; smoke unit, motor and relay coil, and how they are combined.

Greg.P.

On 2/28/2009 7:40 PM Greg.Procter spake thus:

Way to not answer the guy's question. He was asking about *DCC*.

Idiot.

Well, since you have named yourself -- I'll just mention that the answer DOES apply to the DCC systems as presently available AND the presently available smoke units. Now if someone wants to develop a 'chuff able' smoke unit, then a dedicated output from DCC decoders would be useful, but thats for sometime in the future.

Chuck D.

On 2/28/2009 9:04 PM Charles Davis spake thus:

Yeah, guess I jumped on that one a bit too quick ...

Check out MTH HO steam offers.

The smoke unit would yet another 'function'. Many DCC decoders have a bunch of 'function' outputs. *Usually* these are used for all sorts of extra lights, in addition to the head light: marker lights, mars lights, ditch lights, etc. Since a steam loco is not likely to have things like ditch lights, marker lights, or mars lights, you should be able to one these extra functions to control the smoke unit.

Not in my future if it still means wispy white oil vapors condensing on everything in sight.

Smoke units to date look REALLY hokey, with the side effect of laying down a film ofsticky slime on track and rolling stock and scenery and buildings.

Thank you for the response, Idiot.

I answered in terms of DCC.

Regards, Greg.P.

Tri-ang, Lionel and Bachmann (have there been others?) have all at odd times in the past developed, manufactured and sold mechanical "puffing/chuffing" smoke units. Seuthe makes an electronic puffing smoke unit. I think the buying consensus has been that they're not worth the extra cost, at this stage of development.

Regards, Greg.P.

Don't knock yourself too hard David, jumping in without sufficient thought is your forte.

Regards, Greg.P.

Smoke units I suspect draw a lot of power. Make sure yours doesn't draw more than the rating for the output.

Those function outputs don't have the current source/drain capacity to operate a smoke unit - hence my suggestion of using a miniature relay controlled by a function output supplying track current to the smoke unit.

Greg.P.

One can always get a tip3055 (plastic TO-220 version of a 2N3055) transistor and use it to drive the smoke unit.

Or a tip3055 transistor.

: wrote: : : > At Sat, 28 Feb 2009 21:33:00 -0500 Chris wrote: : >

: >>

: >> What kind of decoder do you need to control the smoke function? Ho : >> scale steam loco. : >>

: >> All the decoders that I have looked at mention nothing about this. Just : >> lights : >> and motor. : >

: > The smoke unit would yet another 'function'. Many DCC decoders have a : > bunch : > of 'function' outputs. *Usually* these are used for all sorts of extra : > lights, in addition to the head light: marker lights, mars lights, ditch : > lights, etc. Since a steam loco is not likely to have things like ditch : > lights, marker lights, or mars lights, you should be able to one these : > extra functions to control the smoke unit. : >

: : Those function outputs don't have the current source/drain capacity to : operate a smoke unit - hence my suggestion of using a miniature relay : controlled by a function output supplying track current to the smoke unit. : : Greg.P.

That's exactly what I do with my old American Flyer locos that have been upgraded to Timko can motors and DCC control. With the reversing unit removed, there's plenty of space for the decoder and relay.

It could probably also be done in HO, but there hasn't been a decent HO smoke unit since American Flyer got out of HO. It even 'chuffed' without any electronics. Imagine that.

Len

Sure, if you happen to have a source of DC current. :-)

On 3/1/2009 1:06 PM Greg.Procter spake thus:

Easily provided from track power with a diode and a filter capacitor.

See how at

So add an (equally cheap) bridge rectifier. Both the tip3055 and bridge rectifier are available from Radio Shack...

Thanks for that, very handy. *