Finding a simple a off the shelf turn key controller isn't looking all that simple. I think I'll send the guy who built my controller a link to this forum and see if his electronics guy can come up with a better box. I want one where it is easy to set a larger number of puff duration and frequency times than the one I have now. I would also like to be able to set the number of puffs and then stop. Also, a nice digital display showing the settings and with timer displays would be great.
If you want to see what commercial t-cigarette machine look like check out borgwaldt: https://borgwaldt.hauni.com/en/instruments/smoking-machines/linear.html. I think they start at $30K.
Thanks for all your comments and help.
I don't think it would be difficult to do in hardware. The biggest cost would be in the printed circuit board, but if other people want some that cost would be reduced as you probably can buy 5 for the same price as one. Maybe you could put the specs you would like in one post and I'll have a go at a hardware design. Then we can figure out how to get it built.
You help is very much appreciated. I purchased most of the parts for the machine from Teague Industries in Woodland California. They should be able to build the design.
We are trying to make a machine that emulates e-cigarette users. From clinical and other studies we see that the average user takes a 4 second puff every 30 seconds. It would be nice if we could control the machine to take a 3.5 second puff every 40 seconds. It just seems like a good idea to be able to be flexible in programming the machine.
For the puff duration we would like to supply 12 volts to both the solenoid and the 3-way valve for puff duration times ranging from 0.5 to 10 seconds. We would like have a puff frequencies ranging from 20 to 180 seconds. It would be great to have a puff counter so the puffing would stop after a predetermined number of puff say 3 to 60 puffs.
It would be great if we could control the solenoid which directs the power from the power supply and the valve which directs the suction from the vacuum pump independently. E-cigarette users can push the button on the battery for a second or 2 to preheat the coil before puffing. Right now I control the solenoid which closes the circuit to deliver the power to the coil and open the 3-way valve to the e-cigarette at the same time using the same 12 volts from the controller. A controller that would allow for the power to be delivered to the coil for a 0.5 to 2 seconds before the second 12 volts was sent to the valve would allow for us to simulate this.
The main reason why I want to have an smoking machine is so I can simulate the e-cigarette smoker and collect the vapor in the gas washing bottles for chemical analysis. The biggest driver in e-liquid vaporization and delivery is the voltage. The amount of e-liquid vaporized by a device can go up 8 fold from 3 to 6 volts. Also at higher voltages a lot more formaldehyde is produced. I have very good control over the power (voltage and amperage) being delivered using the constant voltage power supply.
Here is a link to a U-Tube video that shows the machine: running
I think I almost have it.
Let me play it back to you and see if we are on the same page.
You would like a puff duration of 1 to 5 seconds.
You would like one puff cycle to be adjustable from 20 to 40 seconds.
You would like to be able to delay the vacuum valve from .2 to 2 seconds after the coil voltage is applied.
You would like to be able to set the number of puffs from 3 to 60 and you would restart it after each of these?
Now a couple more questions:
What do you mean by a frequency of 20 to 180 seconds?
How would you like to select the times? I envision 2 rotary switches. Say 5 positions for duration - 1 to 5 seconds. One for cycle time - again maybe 5 positions, 20, 25, 30 35 and 40 seconds. And finally maybe a dip switch - a small switch with several positions to set the number of cycles.
We could also make them continuously variable but then you would need something to measure them with.
How accurate do the times need to be? Could 1 second be 1.1 seconds and 5 seconds be 5.5 seconds? Or better?
FWIW: LabView would be cake.
I think what I said earlier was valid. You need a much better HMI interface. I do think the Arduino would be a decent platform with the IDE being the HMI.
Some disadvantages, yes. Not 100% stand-alone.
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I was going to mention "power control" from an electronic load rather than power supply, but your simulating what actually happens.
My "all scenario" brain says the battery is constantly loosing charge and does the model account for that or does it have to?
We're almost there:
Puff frequency and puff cycle are the same. I would like the cycle to be variable from 20 to 180 seconds to simulate puffing from 3 times per minute to once every 3 minutes. 20, 30, 60 90 and 120 would work.
I would like to be able to adjust the puff duration from 1 to 10 seconds with 0.5 second or better accuracy. Times of 2, 3, 4, 5, 6, and 10 second duration are much better than I have now.
I would like to be able to adjust the puff duration independently for the valve and the solenoid. This way I could have a power duration of 5 seconds and a vacuum for 4. This would mimic a user activating the battery for a second before he takes a puff.
Lets shoot for better accuracy then. I can make the clock for the timers adjustable so they can be set more accurately.Rotary switches are good with fixed times and 10% accuracy will work and would be better than variable times for reproducibility.
We're seeing a coefficient of variation of 18% in the delivery/vaporization of e-liquid from 15 puffs from the same device. Delivery is very easy and accurate to measure with e-cigarettes. We simply weigh the device on an analytical balance before and after puffing. Typically we get 80 mg delivered in 15 puffs at 3.7 volts.
That would be nice. Maybe you could let me build it for 75% of what the other guys quote you.If you can design a controller that can do this I'll put you on the paper as an author. You will have the gratitude of the everyone doing e-cigarette research and the FDA.
someone said:Something you wish to quote
How about 0 to 1.8 seconds in steps of .2 seconds?The timings look great except would it be possible to include a 0 second delay on the coil?
Since it is difficult to find a rotary switch with more than 10 positions I would suggest making the puff counter count by fives instead of ones. So you could dial in 5 puffs to 50 puffs in increments of 5..... 5, 10, 15, etc.I'm not sure what you mean by the first option?
I just need to know the current so I know how big the transistor to turn them on needs to be. I think you said they were both 12 volts.I don't have links to the relay and valve but both are 12 volts. I think the relay can handle 10 amps.
Both devices are being driven by the same controller which is fed off a little wall wart. I can put my meter on the connections and see what it says.
I got the relay at Electronics Plus for $24. Having it built in would make it more marketable, but for now, we can leave it external.
When I get to work tomorrow, I'll take some more pictures provide you with the information.
Here are some better pictures which might help you see what's going on. I was wrong about the 12 volts. It's 15 volts and 15.8 on the meter when the controller fires.Oh, I see now it is not a relay, but a solenoid to push the button.
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