With the talk about smoke units, I have a question about getting one to pulse. I have a few USA smoke units with fans. I use airwire units and phoenix sound with magnets and reed switches for chuff. Anyone have any thoughts?
Thanks
Terry
I’ve had the same thoughts. Would a pulsed smoke unit operate by using magnets? Since I try to avoid electronics like the plague, I haven’t delved any further into the qustion, fearing ridicule from some of the less electronically challenged here, LOL. It looks like I am the first to respond to your post. Unfortunately I haven’t the answer. Perhaps one of our better informed members can help.
This had been discussed in another thread. It went very far into the techno, wiz bang, catagory. I was thinking something simpler, like a disk with openings cut in it, that rotates in front of the fan to modulate (pulse) the airflow. But then I am just a simple person.
If using a reed switch with a magnet on the wheel/axle, make sure you try the normally closed reed. This would give more motor on time for one or 2 small magnets and place a diode across the motor to short out the back EMF to simulate a brake to slow the motor down faster.
The problem with a reed switch driven unit is if you stop the loco with the reed over the magnet, the smoke unit will continue to run. I’m looking for something that will make that problem go away.
I was playing around with a USA smoke unit and a 9v battery through a reed switch. Running on battery power i was looking at different ways to power the unit ie: seperate battery power, so I wouldn’t eat up my run time.
Terry
For a realistic display, you would need a volume of smoke to be "chuffed’ out each time. By turning the smoke unit on/off each time you would be defeating the purpose as most smoke units need a few seconds to produce smoke when turned on. I like the idea of the holes in a rotating gizmo with a hole over the outlet of the smoke unit. Adding a small chamber to hold a volume of smoke before each opening would allow a larger puff to escape adding to the effect. If the spin of the opening in the gizmo was timed to the chuff also, it could look awesome.
A USA trains smoke unit does just that. It has a heating element and a separate fan. What I am trying to do is pulse the fan.
Terry
Don’t USA smoke units have two separate power leads? One for the element and one for the fan I believe. They are both plugged into the circuit board supplied with the smoke unit. Couldn’t you insert a reed switch in one of the two wires that supply the fan? This would allow the element to remain on.
Back, way back, Tyco used a piston to give puffs of somke. When the piston was on its intake stroke it would draw in the smoke, so little to none came out of the stack, and then when it was on its exaust stroke it would produce a puff. But the system had issues. Maybe it was because of its size (it was inside of an HO locomotive), its basic design, or how it was made. I dunno, I didnt own one of them puffing locomotives.
That’s an idea! American Flyer and Lionel had pistons to push the smoke out. Of course there was a cam on the drive axle or on the motor gearing, I cannot recall which, that pushed the piston. Trying to get all of that mechanism into a locomotive might be tough. I think it would have to be completely separate from the drive of the locomotive.
seperate may be easier to rig, but it would be harder to time.
USA trains smoke unit does have separate leads for fan and heating element. The heating element can be on it’s the fan that has to pulse. But, when you use a reed switch a problem arises when the loco stops with the reed over the magnet the fan will continue to run. I’m looking for something to stop this from happening. A momentary switch that the reed can trigger. Does anything like this exist?
Moreover, the reed switches are not always good for inductive loads. You can put a “kicker” diode across the motor to help.
But this does not help your problem. You need electronics to do this. Why not have someone do a quick and dirty with a small processor fed by a magnet/reed switch. I bet Dave Bodnar could/would do it.
Small PIC or other cheap processor.
Take magnet input or autochuff.
Have a pulsed output to the fan, it would be easy to just output a single pulse when triggered, and not stay on.
You could also program it to have longer fan pulses when going slower.
Easy… relatively cheap, clearly not as cheap as just the reed relay and magnet.
Greg
That’s exactly what I was looking for. I’ll contact Dave and see if he is willing to do it.
Thanks
Terry
Terry, I have been working on a pulse smoke circuit. I use a PICAXE micro with an H-Bridge. I have had good results with this. When the circuit sees no ground from the chuff contact it gives a small idle like stream of smoke, when the chuff triggers the fan speeds up for a predetermine amount off time then goes back to idle. When the loco is moving the pulsing continues until you reach a certain speed, then the circuit goes into auto chuff so you can still see the individual pulses of smoke. I have been doing additional experiments making my own heaters and trying to get a more universal setup. I run DCC so right now I run my heater straight off the DCC track voltage. I am just a novice at this, Dave may have a better design, but I am doing it for fun.
Steve
Terry, it would be easy to program a microcontroller to supply pulses for the fan but I am not sure that you would get the desired effect. I think a piston or bellows is more likely to give what you want.
I may still have an aristo smoke unit with a fan. If so I can experiment a bit.
Dave
I think a piston would take the place of the fan. The fan is there to push smoke out the stack, The piston would do the same thing. The more complicated you get, the more problems you encounter. Of course, the piston mechanism would have to have mechanical actuation, so that would entail a direct hook-up to the motor or the valve gearing, etc.
David Bodnar said:
Terry, it would be easy to program a microcontroller to supply pulses for the fan but I am not sure that you would get the desired effect. I think a piston or bellows is more likely to give what you want. I may still have an aristo smoke unit with a fan. If so I can experiment a bit. Dave
David
The fan method is pretty well how it’s handled using the various DCC decoders.
Hello All
Lionel “O” gauge steam locos have been pulsing smoke since 1940,s
they use a simple piston loosely linked to the valve gear.
Get ahold of an old Hudson loco to get the parts.
BTW it only pulses once per revolution but still looks OK.
Bill Ewing
The USA fan works great when I manually pulse the fan. Again, building a piston system is not what I want to do. Carving through a frame attaching gears, rods pullies to a piston system attached to a smoke unit seems awfully counter productive for me.
USA trains docksider makes a nice piston system for the steam effect and i looked at using that for about 2 seconds. To me the work involved doesen’t equal the fun I would get out of it.
Terry