Smoke Unit in LVTP-7 - Page 4 - RC Groups
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Feb 12, 2010, 08:43 PM
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Sorry Dan,I was called away.I really like your Idea,you have drawn exactly what I am attempting.The fluid cannot run out of the upper chamber faster than air can go in,that is my theory,the double nipple will allow one hose to attach to the bottom chamber,the other will connect a hose to a refill port.But their is one minor problem.If I unplug the refill port it will allow air in and fluid out at a faster rate I'm thinking.The drawing showing a baffle type opening to allow air pressure to be utilized from the fan is perfect.and easy to make since i also found my modelers guillotine today looking for the power supply,and the plasticard sheets I had with it.But Dan no matter what I do it is not as practical as your unit.The only advantage to my design if any would be modeler having several smoke units on hand.The real discovery is the heating element idea.So many guys dumped these units due to this defect. I am going to build the double chamber smoker design,I have little else to do until the weather warms,although Wisconsin is a lot colder than Tennessee, Thanks Dan,Blake
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Feb 12, 2010, 11:35 PM
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It's a noble idea to try to recycle all the old discarded H.L. smokers out there ; but if it's too complicated and time consuming ; just forget about it and go on with a more simple proven design...
Long before I found out about the last H.L. smokers with the removable top ; I was using my home-made smokers in my tanks....Now that I have done all I could do with the H.L. units ; I'm ready to go back and improve on my own smokers...
I'm using a 2" long x 2" wide x 1 1/4" high aluminum box to build those...
Here's a pic off that box filled to capacity with 35 ml of coloured water ( for show and tell ) ...35 ml is the whole content of the smoke fluid bottle provided by H.L. when you buy a new tank...
Feb 12, 2010, 11:49 PM
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here's a video of my panzer III (using that type of smoker ) that was posted a while ago...
My smoking Panzer lll (1 min 18 sec)
Feb 13, 2010, 01:03 AM
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STRMND54,You are correct.The H/L smokers need replacement by a better unit.I like the amount of smoke your pumping out,so how have you achieved that much smoke? The other reason I have been trying to improve using the H/L smoker base section is the component tray of the Asiatam lower hulls.Space is laid out according to stock units,and I just want to keep it simple,if it only works for my Tiger ok,your unit has a home in my Jagdpanther,without your data on the element we would not of had such an interesting and fun conversation.Dan's smoker is pretty compact,but in some tanks their is more room than others.Could you detail how you design is powered? I assume your using a fan?
Last edited by SAXONDOG; Feb 13, 2010 at 01:26 AM. Reason: picture
Feb 13, 2010, 09:00 PM
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Is this a picture of the unit you want to put in your tank ??
If so ; what is the voltage of your mini-fan ??
And here's a pic of the test smoker I am supposed to rewire and ship to yellowshaker this week . As I do the work I will take as many pics as I can to help you to finish yours...
Feb 13, 2010, 10:46 PM
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The fan in the picture is 12v.07amp 1x1,I have another fan that is 5v.2amp 1.5x1.5 it is a little large,my Tiger runs on a 33oomha Battery.My RX18 is double fan cooled and I run 3:1 Impact gearbox powered by Graupner speed 400's w/12Tpinion gears. My Tank weight is over 22lb.I submit this information to give a picture of my power requirements and to ask your opinion on battery size. Thanks Blake
Last edited by SAXONDOG; Feb 13, 2010 at 10:53 PM.
Feb 13, 2010, 10:55 PM
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I forgot to ask about the "smoke level probe"is this a tube for re-filling and checking level?
Feb 14, 2010, 07:08 PM
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I use the vent tube for both refilling and level indicator...In fact , to be honest ; the whole thing was desing as a refilling tube ...It's a pure accident that it turn out to become a low level indicator .
The 12 Volts fan should be perfect...I had to use a resistor to slow down the speed of my 5 Volts fan because it was pushing too much...
As for your battery pack ; I am running my pershing ( with the smoker posted in the video) for 1 hour non-stop using a 2000 mAh NiMh Mattorro battery from Mato-toys .
I bought a 5000 mAh NiMh pack from a chineese seller on e-bay a couples weeks ago ; for $35.00 I though it was a good deal ...In fact ; even fully charged ; the best running time I had with that battery in my pershing was around 55 minutes...Obviously some dishonest sellers are putting more capacity on the label than into the cells of their batteries . There must be a tread on this forum with a list of honest battery manufacturers and sellers to prevent us from being rubbed ????
I will more than likely buy 2 Matorro packs and plug them in parallel to get 4000 mAh .
At least I know that they'll put out what's on their labels...
Feb 14, 2010, 07:44 PM
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glycol fog juice cheaper than oil

Glycol fog juice is cheaper than glycerin and Heng Long smoke fluid!!!
I followed the advice of DanL and bought 4 litres of glycol smoke fluid yesterday...It turn out that the clerk at the music store made a mistake in checking the price of their smoke fluid the other day...The real price was $35.00 instead of $45.00...So I paid $39.55 with taxes for 4 litres ...
I was paying $6.00 for a 100 ml of glycerin at the drug store...
After mixing with distilled water in a 1/1 ratio I had 200ml of oil for around $6.00 ...
To get 4 litres ( 4000 ml) of oil I would have needed 20 bottles of 200ml at $6.00/bottle = $120.00
So 4 litres of glycerin oil = $120.00 ; compared to $40.00 for glycol...
The savings are obvious..
So thanks DanL for showing me the light...
Feb 15, 2010, 09:34 PM
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mini smoker

Saxondog ; I rewired my spare mini smoker today ...Here's some pics to help you in your project...
Feb 16, 2010, 12:24 PM
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Strmnd54.Just excellent work,perfect explanation.And thank you very much.I have been pre-occupied as you know from my pm but this is truly excellent work.As for Dan's idea about using the different fluid and understanding the cost breakdown I can once again only say your math proves the value of the glycol fluid.Thanks again for helping me to build a better unit, Best regards,Blake
Feb 17, 2010, 09:51 AM
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Resistor Burn Out and Sizing Info

I tested a smoker to failure on purpose to see what happens. I let it run til the fluid was totally evporated away. The wick slowly buned away like a glowing cigarette and the resistor was totally black. I stopped at that point, but I think there is potential for the overheated resistor to start a fire. It only took about 5 minutes after the fluid was gone for this to happen.

I checked the resistance of the resistor to see how it was. It was a 10ohm, 1W, metal oxide resistor, but after overheating it was 145ohms. Obviously starting to break down.

I then checked the resistor in another smoker that I had been testing. The R was up to 14ohms (from 10). So...the resistors are changing with the overheating. But how much are they overheating? I calculated some wattage overload ratios to get an idea of what size wattage to use in different applications. Here's a first cut at some numbers. I think that if the resistor rated wattage is too low relative to the actual circuit wattage, the resistor will fail or possibly even start a fire. I calculated an "Overload Factor" shown in the attachment. From the limited data we have so far, it seems that if that factor is less than 10, the resistor heat will be reasonable but still hot enough to generate smoke. Over 10, like the high overload numbers for these first boat smokers I made, will likely damage the resistors.
Anyway, more work is necessary here to get the wattage sizng guideline defined.

(Note 1: For boats, we need more smoke and have bigger batteries, so the boat smokers are designed to run at 1 or more amps vs less than 1 am for the tank smokers. It's a matter of how much battery power you have to trade off for smoke)

(Note2: The metal oxide resistors I used are rated "flame proof", meaning they won't burst into flame when overheated. We need to find out what type of resistors can handle high overload heat the best)
Last edited by DanL; Feb 17, 2010 at 09:56 AM.
Feb 17, 2010, 10:16 PM
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overpowering resistor

I agree with you . There must be a limit to overpowering resistor . At a certain point ; safety becomes an issue . Now as to what that limit should be remains to be tested . For example , that mini smoker ( the one in the video posted on you-tube on Feb. 04 ) has been running every day since . It's been 14 days today and I took an Ohmmeter reading prior to this posting and read 12.1 Ohms ... Which is very good news ...That resistor is 1/4 Watts ; so I have and overpower ratio of 19 ...
The only change I made on this one was to switch from cotton to kevlar wicks . According to this site :
Kevlar is more heat resistant and has more absorbtion than cotton ...
After a while cotton turns into "charcoal" on the resistor and looses it's absorbtion so the resistor gradually runs dry and burns ....
I guess your next move will be to use (2) 10 Ohms 2 Watts resistors mounted in parallel in your unit ...That should be interesting to see...
Keep us posted ...Norm
Feb 18, 2010, 09:55 AM
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Very interesting that your resistor is stable at a factor of 19. I found a local supplier of many resistors and bought a bunch of different values and types (carbon, metal oxide, wire wound, etc).
I found that some resistors start decreasing resistance deramatically as they heat up, and then go down slightly in value when they cool down. One 15ohm went to less than 10ohm when running (calculated from current measurements) and after cooling was only about 13ohms. Another resistor, after running maybe two hrs total, went from 10ohm to 138ohm when cool. That resistor was running very hot.
Anyway... the approach is great, but resistor stability might be an issue.
For a 12V system, I'm having great smoke output with a 10ohm, 2W resistor (14watt output) . I'd say it's putting out 75% of the smoke that my other 2.2A nichrome percolator (26watt output) puts out, so the resistor unit is not only much simpler ad smaller in design, but also much more efficient.

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