Homebuilt/DIY MTH Smoke Unit upgrade to a K-Line K3380-3768IC Pennsylvania Torpedo Steam Engine

I have a K-Line Torpedo with TMCC.

As stock it uses a piston driven smoke unit. I am dissatifies with this smoke unit due to the impact it has on slow speed operating characteristics of the locomotive.

So I want to replace it with a fan driven MTH unit. After removal of the piston driven unit and a test fit, I have room. The question of course is the electronics.

I have prototyped this circuit and tested it but have not attached it to my Torpedo as yet:

Functionally, the idea is to vari the speed of the smoke unit fan when the locomotive "chuffs" To do this I have "engineered the circuit to idel the fan at ~3VDC and bounce it momenarily to 12VDC when the chuff switch closes. This will approximately synchronize the increase in smoke output with the sound of the chuff.

And yes I am talking about a dirt simple electro-mechanincal synchronization.

The Torpedo has a physical switch for the smoke and using it, the whole circuit is de-engerized. The Torpedo does not have any "labored chuff/smoke" features.

My questions are:

Are the capacitors sized correctly to smooth out the voltage? Since it is not a digital control circuit inthe interests of size I used 100 uF 25v caps.

Are the diodes approprate? The diodes I have used are 1N4005 Sognal Diodes with PIV: 600v, Vf at If :1.6v, If 1A, Maximun Surge Current of 30A at 16ms, REverse Curretn at PIV 10uA.

Is it good to gound the cicuit back into the bridge rectifier for the DC portion, or shold I ground it elsewhere?

I have selected components based on what I had on hand.

Last question is how do you all identify ICs? I suspect that there is an IC that woul dlet me colapse both the signal detection/relay function and the voltage switiching. However, I don't even know where to look.

Thoughts?

Thanks

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3/11/1912:50 PM

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Carl TuvesonOGR Forum Member DIGITAL SUBSCRIBER

I would not use a 12 volt regulator. If the chuff switch stops in the closed position the motor will burn out. I would use a 5 or 6 volt regulator.

Here is a board I made that solves the problems. It runs the fan at an idle voltage between chuffs and when not moving and all of the puffs are the same length. Also the chuff switch resets the timer at each puff.

Carl

3/11/198:27 PM

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Rob JohnstonOGR Forum Member

Thank you Carl

3/11/1910:15 PM

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GGGOGR Forum Member

If you get a PS-1 smoke unit it will connect directly to the TMCC smoke output, but you will not get the chuff effect. Also, you can not drive a MTH PS-2 smoke with 8ohm effective resistance at track voltage for long. It will burn up. The PS-1 has circuitry to control element resistance based on track voltage. Carl, what does the chuff look like with your circuit. G

3/12/198:21 AM

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gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

Here's a board I made to solve the chuffing smoke issue. The idle smoke runs the fan at a lower speed, and the chuffs are variable length based on the speed of the locomotive. The board also offers Rule-17 lighting control and automatic cab light control.

Super-Chuffer II

If you want 4-chuffs/rev, you can get them without magnets and reed switches.

Chuff-Generator

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3/12/1910:10 AM

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Carl TuvesonOGR Forum Member DIGITAL SUBSCRIBER

Here is a video, one of many showing my puffer in action. I use it in my TMCC conversions of the AF Berk. Mikado and Pacifics. Ed Goldin uses them also.

I designed it before gunrunnerjohn made his available. It is cheap to make and works well. The parts are less than $5 .

Here is a web page with more details. http://www.tuveson.com/puffer/puffer.htm