5V PS2 steamer smoke unit

Hi

know this is an old topic but i have a ps2 steamer i might need to just drop a basic reverse board in. Is a 5v dc regulator and bridge rectifier enough to run the smoke or do i need more?

thanks!

You obviously won't have chuffing smoke, but you're close.  It actually takes around 6-6.5 volts to get decent smoke out of the 8 ohm resistor value with the two parallel 16 ohm resistors in the PS/2 smoke unit.  If you use an adjustable power supply, you can drop the voltage for the motor with a couple of diodes, two or three will do the trick, depending on the exact voltage you end up with to get decent smoke.

I'm thinking you might even be able to tap the output of the reverse-unit's bridge rectifier.  Then you can use an eBay 99 cent (free shipping from Asia) DC-to-DC converter modules to get your 6-6.5V DC for the heater voltage.  The diodes to lower the heater to ~5V DC fan voltage would be, say, 20 for 99 cents on eBay (free shipping from Asia).

It sounds like you have a PS2 engine with failed PS2 electronics board set.   If you're a DIY enthusiast and handy with a soldering iron, it might be interesting to see if you can restore puffing smoke which is a nice feature of PS2 vs. PS1.  That is, I'm guessing the flywheel-tach sensor is still functional.  I'm imagining a simple digital counter circuit (less than $5) that uses the existing tach sensor to pulse the 5V fan voltage to effect 4 puffs per revolution of the driver wheel.

Stan, the smoke resistor needs around 3/4 of an amp, so that needs to be considered in picking the power source.

Agreed.   But being the cheapskate, the idea is that generic reverse units are rated in # of Amps relative to the motor.  His steamer may have the smaller, less power hungry Mabuchi RS-3xx motor vs. say a Pittman.  So there may be 3/4 Amp excess capacity in the bridge.  Also, you generally see a heat-sink on the 4 motor drive transistors before you see on on the bridge also suggesting excess capacity.  And, if using the DC-DC $1 switching regulator modules, the current thru the bridge decreases as track voltage increases.  If done right the reverse unit should have been designed to handle stall-current at higher track voltage.  But at, say, 15V on the track, if the regulator output set to 6-6.5V DC, the smoke input current thru the bridge would be maybe half whatever it was at low track voltage.  In other words smoke uses more bridge current when the motor uses less.  Well, that was my logic anyway...

A lot of ifs, ands, and buts. 

A separate 1 or 2 Amp bridge for the smoke would be less than $1.   Just annoyed that the DC-DC eBay modules are 99 cents...but the AC-DC modules with what amounts to an additional 25 cent bridge and 25 cent capacitor and the module jumps the price to $4 or so.

Stan, I can only imagine that is a product of the quantity produced.  I guess the DC-DC modules are produced in high volume and the AC-DC modules in our desired voltage ranges are much lower quantity products.

I know it's an old thread, but pertinent to a question I've got:  Is there any sort of module from China that is a DC-DC regulator (or AC-DC) that outputs regulated 6.5V in a "pulsing" (0-6.5-0) pattern, and with higher input voltage the pulse frequency increases?  Maybe a cheap way to simulate chuff without using the photo-gates or magnets or whatever?  Is there a generic name for such a circuit? (i.e. Proportional Frequency Pulsing Regulator or something fancy like that?).  

Then maybe you could pull off the bridge in the reverse unit like Stan says, and perhaps set the output voltage to something around 7.5 so the effective resistor wattage is still enough to get enough smoke, then add in 3 diodes before the motor?

If I understand correctly, you're proposing using the voltage being applied to the traction motor to control the pulsing frequency of the fan motor?

If so, the fly in the ointment is a given voltage applied to the traction motor can have a wide range of speeds...primarily depending on the load.  For example, apply 10V DC to just an engine and it might move along at 10 sMPH or whatever.  But that same 10V might not even budge an engine pulling some passenger cars.  Then imagine the difference in speed for a consist going up or down a grade at some fixed voltage.

Perhaps you are thinking of the commonly used technique of measuring the generator voltage as a proxy for engine speed.  The idea is to momentary disconnect the drive voltage to the motor and measure the DC voltage that the spinning motor generates (aka back-emf).  There's a lot of geeky math involved but for DC can motors used in O-gauge you'd only need to interrupt motor drive for less than a tenth of a second for the motor to generate a voltage that would be proportional to actual speed.  And if the motor was stalled, generator voltage would be zero which is of course what you want.  I don't know of any off-the-shelf DIY type circuits or ebay modules that perform this function.   But this function is built-in to most DCC decoders for speed control and commonly used in command-control in HO.  These decoders use a microcontroller is to do the timing and control.  If attempting a DIY, I'd lean toward an Arduino.

There is such a circuit, it's called the MTH ProtoSound 1 board.   The way they regulate the chuff rate is the motor voltage.  As Stan notes, it's not exactly synchronized with anything.  They also didn't bother controlling the smoke fan as well.

Most folks that have chuffing smoke want the chuffs synchronized to the sound and truly proportional to speed.  Enter the Super-Chuffer II and the Chuff-Generator, my products to accomplish that goal.

Stan, I thought about Arduino but I'm not sure there's enough room to put a board in anywhere and I don't know much about programming.

I thought maybe some sort of charging/discharging capacitor circuit to actually run the fan. And I understand that the pulse rate won't be exactly matching the speed of the train since the speed would not be proportional to voltage at the motor, but they are at least related.

John, the PS1 board increases fan speed with track voltage, but it doesn't pulse. It's just a constant speed proportional to track voltage. Better than nothing, but "puffs" are fun to see sometimes. 

Look at the Arduino NANO, it's very small.

Why re-invent the wheel, why not use the time honored reed switch and magnet?  The reed switch can drive the motor directly, the fan motor is around 40ma, most reed switches handle 500ma.  You get chuffing that's truly linked to speed, and by adding a little electronics, you can even have continuous smoke at idle.