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Offline Lotuswins

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Smoker w/voltage booster
« on: October 30, 2018, 02:11:11 PM »
Hi Luke,

Since I'm between model builds, and I read somewhere that a booster for the smoker would help it make more or more consistent smoke, I bought these little things the other day off amazon: https://www.amazon.com/gp/product/B06XWSV89D/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

They seem to be able to keep up with the 2.1 amp load of the Taigen smoker, but then wondered actually how to incorporate one into the TCB smoker output.  Since it is a pulsed output to the smoker (right?), the regulator on the booster would probably not like it?  So perhaps the way to go is to separate the heater from the pump motor, and connect it to the AUX output with the booster in series?  Then adjust the booster output until steady smoke appears, and the pump would be regulated by the smoker output?

Think this is the way to go?? This should help with smoker output regardless of battery voltage. Am I on to something or is this just wishful thinking?  Both smoker and Aux would be toggled from the same function.

Jerry

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Offline LukeZ

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Re: Smoker w/voltage booster
« Reply #1 on: October 30, 2018, 08:48:16 PM »
A couple comments. First, the downside of having the heating element powered in parallel with the fan/smoker motor is that at low speeds, the heating element is not going to get as hot as it will at full throttle. It very well could be the case that your source battery has plenty of voltage to create as much smoke as you want, but the way the standard smoker is wired full voltage only gets to the heating element when you're going full speed. At all other speeds it is getting something less.

So the easiest thing to do is wire the heating element separately to its own on/off circuit so it's always either full on or off, not halfway, as you suggest. But when it's full on you may find you don't need the voltage booster.
  • You could connect the heating element directly to the Aux output which can probably handle the current, but recall, the Aux output is capped at 5 volts (rather than full battery voltage). So that may not be enough.
  • You could wire it directly to one of the Motor A or B outputs (if those are free in your implementation), and use the Motor A/B on-off digital functions to treat it as a high-current switch (no more than 2 amps). The motor outputs give full battery voltage.
  • You could use a relay on one of the general purpose outputs and turn that on/off, with the relay connected to your source battery.
If your source battery voltage is not enough to give you the smoke you want, then you can experiment with a voltage booster, but I would not use the smoker output (because of the pulsed signal and also for the reason mentioned above, it is not always full voltage). Nor would I use the Aux output because again that is limited in voltage to begin with as well as current. The way the voltage booster works is that it basically converts current to voltage, you don't get extra voltage for free. Instead, I would toggle the voltage booster with a relay controlled by one of the general purpose outputs. But now we are involving lots of extra bis and bobs.

The best way to increase the heat output of the heating element is not to increase voltage, but to decrease the resistance of the element itself. This will cause the current going through it to increase as per Ohm's law, even though voltage remains constant. The standard resistor used in Taigen/Heng Long heaters is 18 ohms, you could try something less and increase the current (heat) generated. Resistors can be bought for pennies on DigiKey and elsewhere. You want to get one with a relatively high power rating (in watts) so the resistor doesn't just burn up, but of course there are size limitations you are working with as well and if you it is rated too highly it won't heat up sufficiently. Some experimentation would be in order, there were a couple threads back in the day on RCUniverse and RCGroups where guys including myself were goofing off with various resistors. Values from 5-12 ohms were tried, usually with ratings of 1 to 2 watts. Maybe there are more recent experiments recorded in other threads if you do a search.
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Offline Lotuswins

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Re: Smoker w/voltage booster
« Reply #2 on: November 01, 2018, 08:58:31 PM »
Hi Luke,

Thanks so much for the detailed answer.  So, Aux is out, only 5 volts and a limited source, it looks like battery for the heater is the only viable option.  This would be good since it will have the better voltage, and not be a pulsed output.  I thought of changing the resistor, but I think that is not the best of options.  I still like the regulated supply simply to keep the resistor at the optimum temperature to vaporize the smoke fluid.  There must be a narrow band where you need to be, not burning the wick, but providing the optimum amount of vapor.  The battery voltage will fluctuate as it is drained, from 7.2 down to 6.3 volts, which I would think would put the resistor outside the optimum temperature?  I've noticed it on my tanks, as the battery drains the smoker starts to put out less, then finally stop even though the tank is still operational.  So I think the general purpose output switching a relay, or even an rc switch, in parallel with the smoker output (mixed in the radio) would also work. 

I just ordered some 25mm fans, to make the smoker very small, which may help, but I'll start with stock HL/Taigen units and experiment to see what works best for mine. 

Thanks again,  Jerry

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Offline Lotuswins

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Re: Smoker w/voltage booster
« Reply #3 on: November 02, 2018, 04:06:23 PM »
Hi Luke,

Well I started the testing today, with a new Taigen V2 unit (all black if it matters).  I measured the resistance across the resistor, 15.4 ohms, having separated the heater from the motor.  I then plugged the pump into a stock Taigen V1 board, and connected the heater to the battery, with the booster in series.  So, I started out with 7.2 volts on the smoker heater, and started the board up, and all worked fine and the smoke was coming out very nicely.  I let it run for awhile, maybe 5 minutes or so until it started to smell a little burnt, so I reduced the voltage to the heater down to 6.5 (lowest the booster would go), and the smoke output diminished but was still putting out a minimum amount.  Then I noticed the smoke coming out of the side of the box, from the gasket, and noticed the side of the heater deformed, and soft as was the top of the heater.  Oops, melted the darn thing, and upon removing the top of the heater, 1/2 the wick was black and disintegrated.....yikes!! 

So apparently 7.2 volts is a bit much for this smoker.....drat.  I have a backup I can start testing on again, after I clear the room of smoke.  Fortunately its in the garage I'm testing, or I would be in the dog house yet again........

As a side note, I noticed the voltage output from the Taigen board to the smoker (before the booster) would dip down to 5.7 to 6.0 volts when the drive motors would start and run, unloaded yet.  The voltage out of the booster though kept a solid 7.2v or whatever you set it at, regardless of the input voltage, which is what I would expect.

I'm beginning to think the TARR smokers may be the way to go if I continue to have overheating issues.....at least I would only have to replace the wick since the thing is all metal.....

jerry

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Offline LukeZ

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Re: Smoker w/voltage booster
« Reply #4 on: November 04, 2018, 10:12:35 PM »
I don't think the Taigen/Heng Long smokers have a great reputation for longevity generally, though it seems like I have read that as of a few years ago the Taigen's were slightly higher quality. It used to be half the HL smokers burnt out the minute you turned them on.

For sure I do know that if the fluid level ever gets low they will certainly burn out. They need to be soaked in fluid in order not to overheat.
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Offline jhamm

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Re: Smoker w/voltage booster
« Reply #5 on: November 04, 2018, 11:43:01 PM »
For sure I do know that if the fluid level ever gets low they will certainly burn out. They need to be soaked in fluid in order not to overheat.

Right and true...
The original Resistor is a 2 Watt 17 Ohm and burn very fast if you use more than 7,2 Volt.
For more Voltage a Resistor rated 5 Watt arround 12 Ohm is required.