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Old Feb 03, 2010, 09:39 AM
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United States, MN, Brainerd
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smokers

Wow - SDog, thanks for that link. There is excellent smoker info there.

Do the mod to your busted units using the small resistor shown. Those smokers are getting much more smoke per watt than I get.

Here are the differences I can see:

In tanks, unit must be small to fit. In boats, can be bigger.
Tank units must use low watts - not much room for batts.
Tanks - less than 1 amp pulled by smoke unit (about .3 to .6A)
Boats- my smokers pull 2A
Boats need a lot of smoke - wind on water blows it away
HL tank smokers use oil - messy on model
"Fog juice" smokers use glycol solutions. Don't create a mess.

I'm going to change my smoker design and use the info in the link you provided.

When you fix your HL units with the mod, try using fog fluid instead of oil. Once you use oil, the fog fluid wont work well, so fog fluid has to be used on a new, clean unit.
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Old Feb 03, 2010, 12:45 PM
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Thanks Danl,the picture I posted is the units new,they are the new type coming in the newer Heng-Long Tanks.they wire into the drive motors and increase pump speed as the tank speed increases.Most of these units last but a few hours,the element just does not last.Your offer to work/repair these unit is generous,I can tell you many Tankers get frustrated with these smokers,but when they work the effect is very real as they are connected on most tanks straight through to the mufflers,so the smoke exits the same as the real tank.I believe I have a spare smoker that has a burned out element,these units are powered by the MFU unit,IT operates on 7.2v but the smoker unit is 5.0v to the element.Let me see if I can get you some specific information,and a smoker to mail to you,Thanks Dan for you input.By the way I got involved in this discussion because I also have a 1/6 SCALE TIGER tank that I am building,that tank will require a home built unit.Dan I will be in touch,I am sure I can provide you with a unit. Best Regards Blake
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Old Feb 06, 2010, 11:44 AM
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Sudbury ON Canada
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I tried using nichrome wire to fix my H.L. smokers a while ago. The problem is the limited size of the chamber : 1" x 1" x 1" ...
The original heater element in those units is 18 Ohms.
Now if you try to get 18 Ohms with a medium ga. nichrome wire like 32ga. (rated at 12.8 Ohms/ft) ; the wire is gonna be around 16.8 inches long (too much for a cramped space).
So you have to settle for a smaller ga. like 40 ga. (rated at 81.7 Ohms/ft) for which a 2.6 inches long wire will give you 18 Onms...
That's what they did at H.L. ..
But the wire is so small and flimsy that it either breaks or burns...
That's why I am now using resistors as heater elements.
They are cheap , self supporting , easy to weld and small size.
The trick is to drive the resistor way over it's power rating and cooling it off by evaporating smoke fluid on its surface while in the air-flow of a cooling mini-fan...so it doesn't burn...
For example ; a 18 Ohms 1/2 Watts resistor driven at 7.5 Volts ( average operating voltage of a H.L. tank) will have a current of 7.5/18 = 0.42 Amps which gives you a power of 7.5 x 0.42 = 3.1 Watts.
Now 3.1 Watts is around 6 times over the power rating of the resistor...
That's how it works.. It's a trial and errors process..
I've been using cotton candle wicks to wrapped around the resistor for a while and now I upgraded to kevlar wicks ( more heat resistant and more absorbing)..The results are promising : [URL="http://http://www.youtube.com/watch?v=DB1LEU7ZUAs"]
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Old Feb 06, 2010, 12:00 PM
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Well I'm not familiar with posting on this forum ; my video link didn't work .
Soooooo! let's try againhttp://http://www.youtube.com/watch?v=DB1LEU7ZUAs
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Old Feb 06, 2010, 12:11 PM
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And again...
Modified mini H.L. fully proportional smoker test.AVI (2 min 24 sec)
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Old Feb 06, 2010, 06:22 PM
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resistor is a brilliant idea

Using a resistor is brilliant. Makes the whole thing easy. A really good feed system for boats is a small glass capillary that percolates the fluid up out of a reservoir jar to a wick at the top of the tube. I'm thinking a resistor at the bottom of the percolator tube to boil the fluid up and then another wrapped in fiberglass insulation at the top to boil it off. I'm talking fog fluid, not oil.

Anyway, I admire your work. Really moves this smoker design thing forward.
Keep posting. I'll post anything interesting I might find.
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Old Feb 07, 2010, 02:36 AM
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I'm just a little bit confused,possibly I missed something.On the RCU forum you posted some excellent wiring diagrams and gave an optimum resistor rating of 12ohms x 1/2watt,here you describe the reason for 18ohms x 1/2watt.I agree with your math and it does make sense that as long as fluid is being absorbed and the air is moving across the resistor it will remain solid,not burn out and produce the desired smoke effect.So my question is which is the best rating to use? I would also like to add excellent work,math never lies,if you do the math the results are never a matter of guess work but data backed engineering.Pass or fail math is the key. Saxondog http://www.rcuniverse.com/forum/m_58..._2/key_/tm.htm
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Old Feb 07, 2010, 02:49 AM
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On the subject of the fluid chamber size,I am attempting to add another chamber behind and above the main chamber.The second chamber will mount on the fan and on the edge of the main chamber.Now the chambers top section has two nipples for the smoke to escape through to the exit at the back of most tanks.If you were to route one hose into the main chamber top plate adding a hole for to drain fluid into the chamber.here's the key,the second hose is the filler hose and it is plugged after filling.The smaller holes where the element wire passed through the cap are also key,plug one the other allows air in and fluid out,this should double or triple the smoker run time.Saxondog Note:In the picture if you mount the second chamber on the space between the fan and the main chamber this drip method should work. I will try to post pictures later on today,after a little sleep as it is near 2:00A.M. at present. Saxondog
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Old Feb 07, 2010, 12:05 PM
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Quote:
Originally Posted by SAXONDOG View Post
I'm just a little bit confused,possibly I missed something.On the RCU forum you posted some excellent wiring diagrams and gave an optimum resistor rating of 12ohms x 1/2watt,here you describe the reason for 18ohms x 1/2watt.I agree with your math and it does make sense that as long as fluid is being absorbed and the air is moving across the resistor it will remain solid,not burn out and produce the desired smoke effect.So my question is which is the best rating to use? I would also like to add excellent work,math never lies,if you do the math the results are never a matter of guess work but data backed engineering.Pass or fail math is the key. Saxondog http://www.rcuniverse.com/forum/m_58..._2/key_/tm.htm
I know it can be confusing as I did experiment with different values of resistors and configurations...I personnaly set out with the one that I call fully proportional as seen in my last video ; using a 12 Ohms 1/4 Watts resistor...I try to run my pershing at least 45 min. everyday to find out how long it'll last...I like your idea of using broken smokers as an extra fuel tank ; I will need more pics to fully understand how it works...

Here I will try to copy one of my posting from RC universe which sums up where I am now in my experiments...The schematic included in that posting ( the one using a 1 amp. fuse in the line from the motors terminals) is the configuration I have in my pershing right now...


I can now class my experiments in 3 types of smokers:

1- The non-proportional smokers ( using a fan and a 20 Ohms 1/4 Watts resistor) ; constant power to the fan and resistor element
low power consumption; smoke will decrease as the voltage at the battery decreases.

2- The semi-proportional smokers (like the original H.L.) ; (using a fan and a 18 Ohms 1/4 or 1/2 Watts resistor) ; variable power to the fan and constant power to the heater.
low consumption but doesn't put out the smoke when needed : ( If you put a Volmeter at the battery terminals ; You'll notice a voltage drop when you " put the pedal to the metal" ...It means that the power to the heater decreases while the power to the fan increases ; resulting in more air than smoke at the exhaust...

3- Fully proportional smokers ( using a fan and a 12 Ohms 1/4 or 1/2 Watts resistor) ( constant "idle" power to the fan and resistor given by 5 Volts regulator ) ( variable power to fan and resistor given by motors drivers)
Higher power consumption : 0.43 Amps on idle ; around 0.65 Amps full speed
More realistic output...

My concern about that hook up is the extra 0.65 Amps load added to the transistors powering the drive motors. I put a 1 Amps fast blow fuse in line as an extra protection.
I didn't have any problems with the RX-14 board in my Pershing yet but what if I was driving a tiger 1 outside by a hot summer day???
The obvious solution would be to interface with a power transistor to drive the smoker..I got to test that...

Meanwhile I've been experimenting with kevlar wicks ( more heat resistant and more absorbing than cotton) and I too got some mini-fans ( 1" x 1") in order to make the smoker as small as possible.
I put my last modification in my Pershing and uploaded a video on you-tube
Modified mini H.L. fully proportional smoker test.AVI (2 min 24 sec)
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Old Feb 08, 2010, 08:07 AM
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DanL, This resistor method seems to be the way to go. If you change the way you put yours together, let me know. I believe I would like to do it also if it works out better. If you need some of the HL smokers, I will be happy to send you a couple.
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Old Feb 08, 2010, 06:22 PM
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clearly understood excellent explanation of various type and performance.The method I am describing I will post pictures soon,I intend on stacking the second chamber on top and too the front of the hull.one edge on the smoker chamber and the other edge of the chamber on top of the fan. Blake I will try to post later the picture
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Old Feb 08, 2010, 06:26 PM
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I forgot to post this the fan on my smoker in the picture is 1"x1" 12v-o.o7amp 4.75 from rccommand,perfect fit after a little trimming. Blake
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Old Feb 08, 2010, 08:45 PM
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Low and High amp smokers

I've been checking here because of the great smoker work for tanks. I do boats where we can use a lot more amps (we can use much bigger batteries).
If I'm not careful, I'm gonna be building a tank soon!
Anyway, I'm going to try using resistors vs nichrome in my smoker design. I'm also going to compare relative smoke quantity of oil vs glycol fog fluid. In boats, most of us think glycol fog is better.

What do you consider a good oil for your smokers?

Some thoughts to check with you all:
Best fan - the small 1x1" computer fans put out plenty of air flow, are small enough for your tanks and usually pull very low amps.
Wick - cotton, kevlar, etc being used. I use pink fiberglass insulation.
Heating element - resistor better than nichrome. Maybe 2-3 resistors vs one would be better. Use same total resistance, but provide more heat transfer area to wick and fluid.
Fluid feed - solved for boats with percolator tube. Is there a simple "no pump" feed system taht works for tanks?
Smoke proportional with engine speed - highly desired. Is controlling just the fan speed good enough IF the heater doesnt burn out at low fan speed?

Not really expecting answers, but just putting my thoughts out there. I'll work on this tonight and post something tomorrow.

How much dooes a HL smoker cost?

Roughly how much does a decent BIG RC tank cost (a kit, not RTR)?

Anybody interested in firing guns? See my brig....
http://www.rcgroups.com/forums/showa...7&d=1225335600
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Old Feb 08, 2010, 10:48 PM
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DanL, The HL smokers cost about 15.00 for the old units. I think the glycol is the better fluid. Wick? I would try to avoid cotton if I could, less chance of a fire. Proportional control of the fan only would work if the elements don't burn up. I don't know about the cost of a tank kit. I scratch built my LVTP-7.
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Old Feb 08, 2010, 11:59 PM
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Green -
The unit I built for you was large, like the boat units. In that size, the necessary length of a decent diameter nichrome wire is easy to fit in the percolator tube. The wire should not fail. Going to a resistor is perfect for a small unit when there is little space for a smoke unit and when the calc's show that a very small dia (and easily burned/broken) wire is necessary. I don't remember howI configured your wick. At the amps your unit was built to operate at (nearly 2A I think?), you should get a LOT of smoke. If not, a wick fix is in order.
Let me check back on how I built yours. If not enough smoke, I'll figure out how to fix it.
I think strmnd54 has the best HL fix with the resistor. Where there's more room and where a bigger batt is available, the glycol percolator unit pulling somewhere in the rane of 10-20W (depending on V and battery capacity available) is probably a better option than an HL.
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