Model Train Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
47 Posts
Discussion Starter #1 (Edited)
Hello again,

When I restored my 726 I installed a liquid smoke unit because the original pellet unit was burned out. It smokes but not really what I would call well. I accepted this as normal until I saw how much smoke I got from just remaining pill residue on my Hudson.

I thought the problem might be with a poor connection, thus a voltage drop, to the smoke unit. I just double checked all my connections, and even re-ran my "ground" wire and made sure it is solid. I still get what I would consider a trivial amount of smoke with the train at operating voltage (10-12 volts). I can kick the train in neutral and hammer the voltage on the transformer and then it smokes like crazy, but at this kind of voltage but this is way to high to actually run the train on. I have measured the voltage directly at the smoke unit and it is receiving full track voltage. What's going on here?

Thoughts, suggestions, comments?

Anybody have any pictures or video of a working smoke unit?
 

·
Railroad Tycoon
Joined
·
23,975 Posts
Hello again,

When I restored my 726 I installed a liquid smoke unit because the original pellet unit was burned out. It smokes but not really what I would call well. I accepted this as normal until I saw how much smoke I got from just remaining pill residue on my Hudson.

I thought the problem might be with a poor connection, thus a voltage drop, to the smoke unit. I just double checked all my connections, and even re-ran my "ground" wire and made sure it is solid. I still get what I would consider a trivial amount of smoke with the train at operating voltage (10-12 volts). I can kick the train in neutral and hammer the voltage on the transformer and then it smokes like crazy, but at this kind of voltage but this is way to high to actually run the train on. I have measured the voltage directly at the smoke unit and it is receiving full track voltage. What's going on here?

Thoughts, suggestions, comments?

Anybody have any pictures or video of a working smoke unit?

How much liquid did you pour in the beginning?
The first time filling should be around 15 drops.
Do you have long straights? They do pour out smoke at 18v but slow down as the volts drop.

Look at this caboose smoke!:D That is at 18 volts though.

http://www.youtube.com/watch?v=VGzsJ-pOBbo
 

·
Registered
Joined
·
47 Posts
Discussion Starter #3 (Edited)
I don't have any straights long enough to see how it smokes while moving at 18v if that's what you're going for, it would derail on the curves. I have added fluid several times as the output begins to taper off. Is it possible to put too much fluid in it? Seems like I've heard that this will cause fluid to run out the bottom, which is not happening yet.

Just checking with my meter I am getting only .1-.3 ohms of resistance from the neutral side of the smoke unit to any of the drivers. On the hot leg I'm reading .2-.3 ohms of resistance from the pickup roller to smoke unit. Across the smoke unit I measure 8.5 ohms.

Doing the math tells me that at 10 volts I should be dissipating something around 11.7 watts across that resistor which isn't a ton. At 18 volts this would jump to 38 watts, which would explain why it's so much better.
 

·
Admin
Joined
·
44,203 Posts
Well, I have an identical issue with a conversion on a 2026, my Fort Knox Express mentioned in another thread.

One cure that I'm going to try is drop the voltage to the motor.

Use two strings of 3A silicon diodes, about 5 in each direction should do the trick. These are connected in series with the motor. This will require greater voltage on the track to get the same speed out of the motor, and the smoke unit will get the higher direct track voltage.

It is possible to add too much fluid to a smoke unit, been there, done that, made a mess. :D I add a few drops at a time until I get the desired result.
 

·
Premium Member
Joined
·
16,666 Posts
One cure that I'm going to try is drop the voltage to the motor.

Use two strings of 3A silicon diodes, about 5 in each direction should do the trick. These are connected in series with the motor. This will require greater voltage on the track to get the same speed out of the motor, and the smoke unit will get the higher direct track voltage.
I saw you discuss that briefly in another thread.

Just so I understand the wiring, do you mean that the two strings of diodes will be wired in parallel to each other (but in opposing directions to allow current flow with AC power), and that the wired pair will be in series with the input lead to the motor's power ??? Maybe I'm too fuzzy on this diode stuff ...

If is understand you, each diode (in the string) allows current flow, but with some voltage drop, hence "depowering" the motor.

Why not use resistors rather than diodes? Too much heat???

TJ
 

·
Admin
Joined
·
44,203 Posts
Yep, that's right, the diodes each drop around .6 to .7 volts. Resistors aren't a good choice since the voltage drop would be dependent on the current. While the voltage drop across diodes varies somewhat, it's minor when compared to the drop across a resistor.
 
1 - 7 of 7 Posts
Top