An SPDT switch is an overkill for this. All you really need is an SPST across the dropping resistor. If you have a suitable SPDT, it will work of course; but it might be possible to find a smaller, less obtrusive SPST.
As for sizing the resistor, I would put a power resistor, perhaps 1 ohm, 10 watts, in series first and adjust the total voltage to get the best operation--enough smoke but not too hot. Then measure the voltage across the resistor and the voltage across the generator. (If the voltage across the resistor is too small to measure accurately, try repeating the test using a larger resistance.) Divide the resistor's voltage by its resistance to get I, the generator current. Subtract the generator's voltage from 18 volts (if that is the voltage you're operating at) to get E, the voltage drop needed. The resistor value needed is E/I. The power rating should be at least E*I, but using several times that will keep the resistor much cooler. Remember that whatever voltage doesn't appear across the generator will be across the dropping resistor, which you don't want to get too hot either.
Doing it this way, with the smoke generator actually running, avoids the pitfall of guessing wrong about the best voltage to supply to it. And, by doing the measurements with the generator running and hot, you take into account the fact that its resistance goes up somewhat with temperature.
Bob Nelson
lionelsoni wrote: An SPDT switch is an overkill for this. All you really need is an SPST across the dropping resistor. If you have a suitable SPDT, it will work of course; but it might be possible to find a smaller, less obtrusive SPST.
Cheap and dirty trick......I like it must be a technician as an engineer would over think it
Will have to get a smoking caboose just to tryout the circuit or maybe just a smoke unit.
Chief,
The K-Line caboose works fine in regular control(Non TMCC or Non DCS).
Some of the other guys may have a fix for using it in command mode with 18 volts constantly supplied to the track. If the original smoke unit fails I would just change it out to something better.
Lee F.
Tell me something here. Why does everybody run everything at 18 volts on your TMCC..................
I have been runnin my TMCC at 14-16 volts and haven't had any problems with stuff burning out or getting to hot. I have a few K-line smokin' cabooses and a few TMCC engines with smoke and haven't had any problems. They all smoke like a champ. I never had mine track voltage set at 18 volts or higher and I'm using the old ZW's and the KW's.
I always see topic being brought up. Maybe you guys should cut back on your track voltage.
Hev
Just what is an exceptable(recomended voltage) for TMCC???
I open my throttles on my PW Z W all the way almost all of the time but sometimes I cut it back a couple volts to save on my bulbs. I never had a problem except once with a new Lionel caboose that the wires inside of it were so tiny it burnt them all up, now, no lights or smoke in it & I removed the rest of the wires !
Thanks, John
God bless TCA 05-58541 Benefactor Member of the NRA, Member of the American Legion, Retired Boss Hog of Roseyville , KC&D Qualified
The TMCC manual does call for 18V. I haven't tried running on lesser. Kinda late to test my smoking caboose on lower voltage now.
Bruce Webster
alexweiihman wrote:I talked to some one who use to work for K-line and they said to add a 15om resistor in that unit because alot of people were running the caboose with tmcc and the resistor orginally came with it couldn`t handle that much current.
What wattage should the 15 ohm resister be able to handle? I just picked up some 10 ohm resisters at Radio Shack (some could carry either 1/4 or 1/2 watt and the others were for 1 watt) I was hoping the 10 ohm would be sufficient enough since I did not see any 15 ohm. I believe I saw 100 and 150 ohm resisters though (I could be wrong since the drawers had many types). Putting one of these in line with the smoke unit should be a "simple" modification (which is what I was looking for since I only plan to run these when running TMCC or DCS)
Thanks!
David
Impossible to say without some measurements. However, if we assume that 15 ohms is the right value and guess that it was intended to reduce the voltage by about 5 volts, from 18 to 13, then the power that it has to handle is 1 2/3 watt. To keep the resistor cool, I would triple it, to at least 5 watts.
Radio Shack sells 10-ohm, 1-watt resistors (271-151). Two of these in parallel would be 5 ohms, 2 watts, which would be ample to handle the one-third of the power, 556 milliwatts, that it would be called upon to if put in series with their 10-ohm, 10-watt resistor (271-132).
It would be neater to find a 15-ohm, 5- or 10-watt resistor from a distributor like Mouser or Digi-key, however. Mouser has a 5-watt (526-5W015) for $.35.
bibeaud wrote: alexweiihman wrote:I talked to some one who use to work for K-line and they said to add a 15om resistor in that unit because alot of people were running the caboose with tmcc and the resistor orginally came with it couldn`t handle that much current. What wattage should the 15 ohm resister be able to handle? I just picked up some 10 ohm resisters at Radio Shack (some could carry either 1/4 or 1/2 watt and the others were for 1 watt) I was hoping the 10 ohm would be sufficient enough since I did not see any 15 ohm. I believe I saw 100 and 150 ohm resisters though (I could be wrong since the drawers had many types). Putting one of these in line with the smoke unit should be a "simple" modification (which is what I was looking for since I only plan to run these when running TMCC or DCS)Thanks!David
I dont know exactly if ten would work but the safest bet would be 15 om
No. That will be 30 ohms.
You could do a 2x2 series-parallel circuit with 4 of them, which would raise the power rating to 2 watts while keeping the resistance at 15 ohms. However, I think 2 watts is cutting it a little close. A 3x3 series-parallel circuit would get you up to 4.5 watts, which is enough, but would use a whopping 9 resistors.
Check out this link, it will take care of the problems of "Caboose China Syndrome". I have the same caboose that they use in the demo, however I haven't done it yet because I would prefer a fan driven smoker instead of that irritating plastic puffer system.
http://www.electricrr.com/SmokingCaboose/Caboose.htm
Any other of the old geezers, like me, remember the baseball cards in the spokes of your bicycle trick? That is exactly what that puffer system sounds like to me.
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