TMCC and K-Line Smoking Caboose

[Anonymous]

I bought a K-Lin NC5 Pensy smoking caboose this weekend. Brought it home and ran it w/my TMCC engine. It smoked great but then we noticed the smell of burning plastic. It melted a hole in the roof and bent the side of the car. I'm a newbie so I had no idea this could happen. My train shop willingly gave me a new caboose and he suggested until he finds some part (can't remember what he called it) to limit the power to the caboose that I not run it w/TMCC engines and only in conventional. What's this all about. My TMCC engine is an electric BB1 so it doesn't smoke, but will I have problems w/TMCC smoking engines as well.

Can someone explain this to me in plain English and not tech talk? I stil don't understand Ohms and regulators and such stuff.

Thanks

Marc

[Anonymous]

TMCC normally runs at full 18 volts to the track. A lot of pre-command equipment wasn't designed to handled sustained high voltage. Check the bottom of the caboose. A lof ot K-Line equipment has an on-off switch or a command/conventional switch. The command switch, if avialable, drops the voltage to the smoke unit/lights to keep them from overloading. You can wire in some diodes or a resistor to do the same thing.

[ChiefEagles]

Bob Nelson will probably tell you what to use. He has me using bridge rectifiers to reduce voltages. Parts are from Radio Shack. Easy to build. He may have a resister or something else. Give him time. 18V is really too hot for these things. Spankybird [Tom P] had an earlier made Lionel caboose with smoke do a melt down. They should give a warning in old print on command control [bith DCS and TMCC] 18 V is too high.

[Anonymous]

Chief

Yes a warning should absolutely be given. I am new to this hobby and had NO idea.
Problem with reducing voltage is that these things don't seem to smoke at all when voltage is too low. When I run my conventional engines on a reasonable speed they hardly smoke. I have to sort of "warm them up" in neutral w/ the controller handle turned all the way up.

Thanks

Marc

[ChiefEagles]

Well, if it does not have a switch, you can install one and make it full voltage and through the bridge rectifier. The bridge rectifier can control teh voltage by adding or subtracting the rectifiers. You get it where it is smoking good with the bridge rectifier and then you get a switch [mini] to switch track voltage from rectifier to straight track voltage. Now I know that sounds conplicated but it is not. If you can solder, you have it made. Bob has not replied so he may be busy tonight. Sent him a heads up email.

[lionelsoni]

Here I am, Frank.

There are two general ways to reduce the voltage. If the smoke unit is simply a heater, you can put a single rectifier diode in series with it. A 3-ampere diode should be big enough. This will reduce the voltage by 30 percent, that is, from 18 to about 13 volts. The waveform will no longer be sinusoidal; but the heater does not care about that. If it has a motor to run a blower, it is best to leave the motor alone and put the diode in series only with the heater element. Depending on how it is made, separating the wiring to the two may be difficult. A further caution is that the diode will draw a DC component of current from the transformer, but probably far less than enough to harm it. But there is a remote possibility that it will cause a small DC offset which a whistle circuit could see as a command to blow. A great advantage of the single-diode method, aside from its simplicity, is that it wastes almost no energy; so the diode does not get very hot.

The other general method is to put something in series with the smoke generator to drop the excess part of the voltage. Likely candidates are a resistor, a lamp, or diode pairs. These will get hot, but the combination of smoke generator and dropping element together will not be nearly as hot as the smoke generator by itself is now.

To use a resistor, I would first put the caboose on a variable-voltage transformer in series with a 1-ohm resistor and adjust it to the desired smoke level. Then measure the voltage across the caboose and the voltage across the resistor. Divide the voltage across the resistor by the resistance in ohms (1) to get the current in amperes. You will want to drop the 18 volts from the TMCC by the difference between 18 and the voltage you measured across the caboose. Let's say the caboose voltage was 13 volts; so the voltage to be dropped is 5 volts. Divide that by the current. Let's say that you measured 1.5 volts across the 1-ohm resistor, meaning that the current was 1.5 amperes. So 5 volts of drop divided by 1.5 amperes of current gives 3.3 ohms for the dropping resistor. Next calculate the power that the dropping resistor will have to dissipate as heat. This is the 5 volts of drop times the 1.5 amperes of current, or 7.5 watts. A little larger would be even better to keep it cooler; but you will need at least a 10-watt resistor.

If the voltage across the original 1-ohm resistor is too small to measure accurately, use a larger resistance value; and remember to divide the voltage by that value in calculating the current.

Another way is the diode-pair trick. In this you take a pair of rectifier diodes and wire them together back-to-back. Each diode has a stripe around it at the cathode end. You wire the cathode of each diode to the anode (the end without a stripe) of the other. Then you put this pair in series with the smoke generator. This reduces the voltage by about .6 volts. That's not enough; so you will need quite a few of these pairs in series to get a substantial reduction. A way to get more pairs in a small package is to use a bridge-rectifier module instead of individual diodes. Connect the + and - terminals together and then use the other two terminals to wire the module into the circuit. This is equivalent to two pairs of individual diodes, or four diodes. You will still probably need several. With the diode trick, you should probably just add or remove diodes until the smoke is the way you like it.

[ChiefEagles]

Here is a picture of the bridge rectifier I built to reduce the voltage for a smoke unit I put in a dummy. Since I run in command, I did this to keep from burning up the unit. Actually ended up with on 3 in series to reduce the voltage.

May look complicated but it is easy to do.

[phillyreading]

Does this problem happen with the DCS system by MTH also? I have a K-Line smoking caboose and am wondering if I need to modify it too before something happens to it. However my caboose has an on/off switch on the bottom of it.
Lee Fritz

[spankybird]

QUOTE: Originally posted by phillyreading

Does this problem happen with the DCS system by MTH also? I have a K-Line smoking caboose and am wondering if I need to modify it too before something happens to it. However my caboose has an on/off switch on the bottom of it.
Lee Fritz

I have 3 different K-line's with smoke and haven't had any problems with them while running under DCS. [;)] Now my Lionel one is a different story.[:(]

[ChiefEagles]

DCS runs constant 18V. If it has problems with TMCC, it will with DCS. BTW: they both will operate with less voltage. Engines respond different and don't have as much top speed. Most will jump the track at top speed on 18V anyway.

[phillyreading]

ChiefEagles,
Where did you get your bridge rectfier? The rectifier I bought from Radio Shack looks very differant, part number two76-1181(my two button just quit) full wave rectifier rated 8amps.
Lee Fritz

[Anonymous]

The Caboose has an on off switch. Nevertheless, you guys might as well be speaking chineese to me.
Thanks for the info anyway.

Spankybird, I have a macaw as well. You can see him at my website, www.thecoinopcollector.com

Marc