Reduce voltage to MTH smoke unit

[lionelsoni]

Frank Eagles sent me this by e-mail:

"I have put 8 bridge rectifiers in a row on an MTH smoke unit to reduce the track power so it will smoke like a diesel and not a steamer.  Still smokes a lot.  Suggestions??  If I reduce transformer voltage, she will slow down.  I'm running it on command so 18V.  Something in the board must be beefing the voltage back up to a point.   On a Lionel smoke unit, 3 bridge rectifiers will reduce it enough to get good smoke but not too much."

I don't know what's inside the smoke generator; but it is acting like it is regulated.  That is, the basic generator is designed to put out full smoke at some low voltage; and the electronics reduces the voltage that you give it, or otherwise slows down the generator in some way, to keep the smoke at the intended level.  So it's very unlikely that it actually "beef[s]...the voltage back up"; but the effect is the same.

You are reducing the RMS voltage substantially, probably to somewhere around 10 or 12 volts.  However, short of reverse-engineering the smoke generator, about the only option is reducing it even more, if you've got room for the diodes, to below the point at which it is regulated.  You could use a dropping resistor in this case instead of the diodes, since the track voltage is constant.  That will be a trial-and-error process.  If you do it, be sure that you stay well below the resistor's power rating.  Measuring the voltage across it.  The power is the square of that voltage, divided by the resistance, and should be less than half the rated power to keep the resistor reasonably cool.

[DMUinCT]

If you are running in Command (DCS), push the "Menu" button, move to the second line "Control", push wheel.  "Smoke Volume" is selected (has arrow pointing to it), push wheel.  Push S1 (Min), S2 (Med), or S3 (Max) to select smoke volume.  Push "Menu" 3 times to return to operation. 

[ChiefEagles]

Nope.  Dummy that has a smoke unit added.