Chuff switch for fan driven smoke

I think this is the approach lionel took with the super smoke units.  They used an ACREG item that also powered the smoke unit.  I imagine it pulsed extra voltage to the fan unit, but I beleive it was driven via the R2LC vice a switch.  Worst that can happen is wearing out a $6 fan motor early.  G

Every smoke unit with a fan now does exactly that-turns it on and off at low speeds until you get going fast enough to turn the fan motor on continuously, so it shouldn't hurt anymore than we already do.....

Thanks guys, I wasn't sure exactly how they did that, I guess I never looked close enough at one that has fan driven smoke.

Seems like a pretty simple thing to do, a reed switch and one of the tiny magnets.

Are you running conventional? Chuff switches are useless if you're running conventional because the heating element requires constant voltage to stay hot and work properly with the fan turning on and off. If you're running dcc and your engine has chuff sound you could most likely wire the fan motor to the chuff board so every time the chuff sounds then the smoke will puff. I've not done this conversion to MTH but I have done it to Lionel.

Thomas

I'm running an MTH locomotive converted to TMCC using the ERR Cruise Commander.  The MTH fan driven unit has the smoke heater and fan separately powered.  I'm planning on having the smoke unit energized all the time, just flipping the fan on and off with the chuff switch.

The fan unit is wired seperately because your engine is running on A/C power supply and the smoke fan is D/C. your fan motor should be wired to a board in which The A/C power is driven thru the board and refigured to D/C before reaching the fan motor. If you unplug the fan motor and hook it straight up to track power it will run eratic for a few seconds then it'll pop with a whisp of smoke never to run again. The smoke unit can be rewired to puff with a two wire swap and a little resoldering on the smoke board if you have a sound board with chuff sound. Heres the easiest safest way : Take a 1 amp chuff switch and splice it directly into the power side of your fan motor then mount the chuff switch inside the steam chest where a drive rod can move in and out to activate the switch. Hope this will help you on your quest for the puff.

Thomas

Thanks, I realize the motor is running from low voltage DC on the regulator board.  Your description is exactly what I was considering, but I'm thinking of using a reed switch and a magnet, I think that will be easier to mount and get working.  I also have a few of the tiny microswitches if that turns out to be the better solution.

A reed switch can be configured to trip more than once per revolution where as in most cases the chuff switch above can only be tripped once per wheel revolution giving you a less than desired prototipical chuff cycle. The reed switch is a good choice.

Thomas

I'll just have to figure out where to mount the magnet(s) to get the best sound.

I have to get the conversion finished first, I'm just starting on my custom lights in the shell now.   I'm also waiting on the Cruise Commander kit so I'll have some power.

It would be nice if someone has a picture or two of a conversion like this to post. I have been pondering doing this exact thing on a couple of Lionels that have continuous smoke. I guess I have been spoiled by PS-2 chuff smoke units and now nothing else looks right.

Rod

Well, I'll try to take pictures as I go, if it works out well I'll post them.   If it doesn't work as I expect, I'll just bury the pictures and you'll never hear about it again.  

I think the exact placement of the magnet or magnets will depend on the layout in an individual locomotive.  The one I'm converting happens to be an MTH with PS-1, and there's no chuff provision.  On the good side, I get lots of smoke from the smoke unit, so it bodes well for a conversion.  I'm also faced with the issue of having to provide a separate chuff switch for the RailSounds board, so I may have to get creative there, perhaps a SPDT relay to provide isolated contacts for the two purposes.  Decisions...decisions...decisions...

I don't think it'll work that great as PS2 reverses the fan motr polarity at each chug to stop the fan. Without the polarity change the fan motor will simply speed up and slow down.

Well, I can do a reversal without too much trouble if that's required.  A DPDT relay or perhaps electronically.  I'm going to be wiring a small board for the custom lighting anyway, so I'll have a place for a few more components.  The nice thing about this locomotive is there is tons of space inside, so I have room to get creative.   The Cruise Commander will be in the locomotive, and the RailSounds Commander will be in the tender.

I might get by by just shorting the leads of the motor with the relay when I want to stop it, that will stop a freewheeling DC motor in a hurry.

John,  Here is a part number Lionel uses.  Your method probably less expensive.

Remember that the PS-1 smoke unit has a 2 stage element, depending on voltage.  You may want to capitalize on that also.  G

Well, the TMCC smoke output has a "turbo" function if you hold the "smoke on" key, but that's probably not what you're talking about.

I see that PS-1 smoke units have two resistors, but I thought they were simply wired in parallel.  How does the 2-stage smoke work?

Do you have a reference for that Lionel part, I didn't find it.

MTH PS1 smoke units do not reverse fan polarity. However, be  advised if you stop the engine w/power on unit while the fan is off for any length of time the unit can overheat quickly. If anyone wants a schematic of the PS1 smoke unit, email me at aglenney@sbcglobal.net 

Good point on the overheating, I'll have to take that into account.  It's looking more like a custom circuit to do the chuff management at this point.  Perhaps I'd have to have a timer that if I didn't get a chuff for a couple of seconds, I'd just start the fan until I did.  Time to dig out my supply of 555 timers.

John, No they wind up in series.  The first number is the part number.

This is Lionels super smoke unit.  I think there is documentation about a patent infringement with MTH.  It is wired to the R2LC and the smoke unit to allow for chuff puff! :-)

I think your method wants to leave the fan on at a low voltage and use your chuff switch, or a modified timer to pulse higher voltage to simulate the higher smoke output.

Since you are going TMCC and will have full voltage, the current PS-1 smoke unit will have the heaters on full.  You may want to look at the MTH web site they have info on the smoke unit in the service area, and you can look at the mod done to the unit if you do a PS-2 conversion.  It includes cutting a trace on the smoke unit.

The regulator may be a more elegant solution, though a $30 one, but no additional switches and magnets.    G

Actually, I like the idea of running the fan slow, then hitting it with a shot for the chuff, that might eliminate the issue of it overheating.  The output of the R2LC is not full 18 volts, it's actually half-wave.  When you apply the boost, you get the full wave output voltage, but I don't believe that's 18V either.  FWIW, the smoke unit in this PS/1 locomotive is connected directly to track power, so it's getting whatever it takes to move the locomotive and cars.

Got the schematic for the PS/1 smoke unit, it's more complicated than it would appear.  The smoke resistors are in series, and they have a voltage switch to bypass to a single one when the voltage goes low, I guess to keep the smoke output up at slow speed by heating it hotter.

I had no idea how to find the service note you mention over at MTH, not the best designed site on the planet.