ProtoSound 2 to DCC Conversion: How do the various components work?

Ed KapuscinskiOGR Forum Member

I've been working on converting an MTH PRR H3 2-8-0 over to DCC using a TCS WowSteam decoder. So far so good (although the MTH wiring scheme made no sense).

https://www.youtube.com/watch?v=rqTFD8jcBU0

However, I want to try and use the smoke generator and possibly the synchro cam.

Do any of you folks have info about how those components work and are wired?

I know, for example, I know what wires are connected to what:

Dark Blue - Cam
Orange - Cam
Brown - Smoke Heater
Green - Smoke Fan
Gray - Smoke Fan

But I don't know the details of what those inputs and outputs actually are doing.

Any help would be appreciated.

11/10/2010:07 AM

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sinclairOGR Forum Member

As far as I know, there isn't a decoder that can run a native O smoke unit, they draw too much current. The cam should be an on/off signal, so does the decoder have a chug trigger input? I would think one of the cam's wires goes to the trigger on the decoder and the other either to ground or power, depending on how the decoder looks for a trigger.

I think you'd get more help in the DCC forum then the MTH one.

11/10/2011:12 AM

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gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

The smoke heater is two 16 ohm resistors in parallel to yield 8 ohms. The smoke motor runs on 5VDC. The tach reader is simply a reflective optical sensor that pulses for each stripe, you need power an an analog input circuit to use it.

The smoke heater and motor are managed by the PS/2 board, they use PWM control to vary the smoke volume and fan speed. The tach reader is simply an input to the PS/2 board to allow the electronics to control speed and to time the chuff signal and smoke puffing.

11/10/203:02 PM

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Ed KapuscinskiOGR Forum Member

Ok awesome, that is all very helpful.

So I'm guessing I just put +12v on the one side of the tach and then feed the other end into the chuff input on the decoder (depending on what it expects, I'll dig into that separately).

As for smoke, I think I'll give that a pass for now. I guess the way to do it is to use relays to control the on/off and then let the decoder figure out the fan situation (it's got an output for it).

Thank you for the help!!

11/10/203:18 PM

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gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

12V on the tach reader will turn it to cinders, it's rated at 5V. Also, unless the chuff input on the decoder does a division on the tach reader output, you'll have a problem as you're getting 24 pulses with each rev of the flywheel now. I also doubt the decoder input circuit will deal with the decoder analog output.

What you really need is something that takes those tach pulses and turns them into chuffs at the correct rate. As it turns out, there is such a product. Programmable Chuff-Generator. This also runs on 5VDC, but outputs a digital pulse at any chuff rate you program in during installation.