Building a Digital Vaporizer (Brain Dump)

[mi643]

Vab999,

I have ordered the Aoyue 852 yesterday, it cost me 88 euro, incl. shipping.
Hope it will work for vaporizing..
Here some links.

http://www.youtube.com/watch?v=Z-6v...285BE7177&index=3&playnext=2&playnext_from=PL

http://www.youtube.com/watch?v=MOEH...285BE7177&playnext=1&playnext_from=PL&index=2

http://www.youtube.com/watch?v=quGs3q9nsA8

http://www.pcb-soldering.co.uk/index.php?target=categories&category_id=41

I'm going on a holiday for a month, after that i will start a new topic about my adventure whit this machine.

Greetz

 

[vap999]

I have ordered the Aoyue 852 yesterday, it cost me 88 euro, incl. shipping.
Hope it will work for vaporizing.

It's got solid-state variable temperature and air speed controls, an air flow meter, a built in external arm/holder, probably more heating power than needed for vaporization, has lots of attachments that look likely to interface with parts from existing vaporizers, has a ceramic heating element, and it works on 24 volts DC. Presuming you use the right stems, vapor tubes, whips or whatever that interface with the outports they offer, it looks as though it should work very well.

We all welcome hearing your report.

 

[mi643]

Delivery was faster then expected, the thing is burning in on my kitchen table as we speak..
Now i have to find the right bong/balloon setup.... i have been looking at some laboratory stuff, and there are some interesting things i can use..



Gonna play whit my new toy now....

 

[skippymcware]

Update:

That Aoyue 852 looks pretty nice. My only problem is that it looks like it wants a constant flow rate. Is this the case?

In other news, I did a bunch of testing with a friend over the weekend. It was a tough job and required a lot of snacks, but somebody had to do it. For science, I mean. We ended up with the heater temp at 430 and the air temp, on average, just over 380. Here is the graph of our last test:



That part where it jumps up to 325 in the beginning is where I plug the thermocouple in. That is the temperature of the still air in the heater tube. You can see the difference in the hitting style of my friend and I. I hit it first and, like always, I cause the air temp to drop over the length of the hit. He somehow manages to maintain a relatively constant temp. More importantly, though, those striped lines are 370 and 380, and we are just above them. Some of my hits even go below 370.


On another note, here is a pic of a standard food grade silicone hose and a tygon high purity silicone hose.



The darker hose is the standard silicone. Initially, I said that I thought that you were going to pay a lot for tygon because it was really good at things that didn't matter in this application. Now that I have tried the two back to back, however, I think it does have some useful features. It definitely has less of a taste than the standard silicone. The silicone has a very mild taste, but the tygon is almost tasteless. To be fair, however, the standard tubing's taste was covered up very quickly once I used it a few times. The tygon is also much more flexible. This is nice if you want to put it in your bag, coil it up, or shove it in a tight space. The only downside to this is that the hose will fold over on itself once in a while because it is so soft. For the most part, this happens right where it meets the whip handle. Lastly, the tygon looks much nicer. Granted, the standard silicone in that picture was used for a while, but the tygon definitely has a nicer clear white color to begin with.

The next step in this whole project will be to map out temp vs. flow rate and try using the air thermocouple as the control input. Should be interesting.

-skippy

 

[Hippie Dickie]

is that showing a 100F drop in 30 seconds? isn't there any temp feedback control going on?

and i feel ya on the testing ... it's arduous.

 

[skippymcware]

the control input in this setup is the heater temp. The heater temp barely moves at all when you take a hit. This is not because the control system is good, but because there is a lot of thermal mass and the heater just isn't effected by the air flowing through the tube. Because this tube is .065", the system works mostly off of its thermal capacity. As I mentioned, the next step is to see what this thing does when I use the air temp as the control input.

I checked the data, it is a 80 degree drop in 6 seconds and a 100 degree drop in 16 seconds.

This is slightly misleading though, because this is only after the flow has stopped. If you were to start hitting it again the temp would blast straight back up as is seen on the front side of those peaks.

 

[Hippie Dickie]

well, i see the minor movement during the hit - yours is down a bit, buddy's stays pretty flat. So why does the temp drop like that when the hit stops?

but taking a hit causes the temp to go back to the set point?

i don't understand what is controlling the temperature.

in my vape, the temp starts to drop when i take a hit, but the PWM turns on more current to the coil to bring the temp back to the setpoint.

 

[skippymcware]

Hippie,

If you look at the picture of the setup in previous posts it will become more clear, i think. In my previous post, I was saying that the heater temp barely moves. I was not implying that the air temp, seen in the above graph, is also stable.

Here is the setup:
There is a thermocouple in the heater that the controller is using as its control input. The controller is doing nothing more than maintaining a heater core temperature of 430 degrees. The thermocouple is sitting in the middle of the tube. When you draw air through the tube it stirs the air because I have a twisted tape turbulator in there.

http://pedco2000.com/images/Turbulator1640x480x100.jpg
*Mine is shaped exactly like the thing in the middle there (except it is made out of tin foil)

So, anyway, when you hit it, it stirs everything up and you get much hotter air passing over the thermocouple. When you aren't hitting it, the air in the center of the tube cools extremely quickly and gives you that low idle reading.

 

[Hippie Dickie]

thanks for explaining that. clearly i'm not keeping up with the lecture notes. it got too complicated for me to follow.

 

[skippymcware]

ya... if you were here and we had the thing in front of us it would be way easier. explaining things through the internets is hard as it is. Nevermind explaining something with this many details.

 

[Hippie Dickie]

did you get your MAX6675s yet? you know you can get samples - only the leadfree version, however. $3.95 in 1000s, $15.95 in units (ouch!).

 

[skippymcware]

I haven't got my hands on one yet. I am still working on sorting out exactly what the basis of this vape is going to be. Once I nail a heater setup I will start messing around with IC's.

 

[Hippie Dickie]

That's a good way to proceed ... pretty much what i did, too.

The MAX6675 is only available as surface mount. If you haven't dealt with that technology yet, there are some good Wikipedia articles and YouTube videos as training material.

 

[mi643]

That Aoyue 852 looks pretty nice. My only problem is that it looks like it wants a constant flow rate. Is this the case?

The thing works great.
Heating up is fast, and the temperature is very stable.

Downside is the noise it makes, but whit a bit of isolation it now is not that bad.
And there is always blowing some air out of the thing.. minimum when it is on the lowest setting, but there are always some bubbles in my bong.

When i'm back from turkey i will make some pictures and a little review.

Question: does anybody know what lightbulb the AroMed 4.0 uses? http://www.aromed.com/en/index.html Is it possible/simple to rebuild my station whit a bulb instead of the heating element?

 

[stinkmeaner]

Question: does anybody know what lightbulb the AroMed 4.0 uses? http://www.aromed.com/en/index.html Is it possible/simple to rebuild my station whit a bulb instead of the heating element?

I dont think the bulb would give off enough heat with the air flow of the station.

 

[stinkmeaner]

skippymcware I really like your prototype and have been contemplating building one of my own. If you haven't found a suitable housing for yours look into tattoo or PC power supplies, they are going to have a built in AC/DC converter and it seems like most of the digital box vaporizers are using this idea.

The first one looks like one of the Vaporfection Stealth models

 

[skippymcware]

stinkmeaner,

Thanks for the heads up on those enclosures. They look very nice. I will definitely check them out when I get to that point.



At the moment, though, I am going to put the large tabletop vaporizer on hold. Looking at the temperature vs time graph I posted earlier, I think it is pretty obvious that it does not need a more complicated control device. For the moment, I am going to take a break from this device and have started work on something like Hippie's portable vape. To this end, I have already done quit a bit of work. The biggest step forward was the flow rate testing I did. In summary, I used my aquarium pump on seven different flow settings. I then recorded the air temperature over a 15 second window. I figured this was about an average hit length. Here is the excel file with all the data:



Here are the seven individual temperature graphs from the tests. All of these have the turbulator in them, and the drop that you see over the 15 sec. is almost surely the tinfoil cooling off as you pass air over it:









[EDIT]
Here are the graphs from the flow tests without the turbulator. They are more clear. The turbulator kind of messes with things.










[/EDIT]

Anyway, all of this told me that my original estimate of 1.5 CFM was far too high. If I compare the outlet temperature of these tests to the outlet temperature I get when I hit it, I find that I must be hitting it at less than .25 CFM. If this is true, 25 watts should, technically, be enough to accomplish the goal. Given that there will be heat loss, people may hit harder than that, and we might want to raise the temp a little, we get the following:

Necessary Power = SCFM x (Tout - Tin) / 3 = .5 x (450-70) / 3 = 63.3 Watts

Just to be safe, let's bump this up to Hippie Dickie's 75 Watts. I should have just listened to him the whole time. My only caveat is that I had to rig up a volume measurement system using a plastic bag. But, as you can see from the excel file, everything was pretty consistent. If I decided to do this right, I would get a rotameter. Seen here:

http://www.omega.com/ppt/pptsc.asp?ref=FL4200_4600

Hilariously, mcmaster sells those as well.

Anyway, after I did those tests I found myself in this awkward position where I had a much lower power requirement and didn't really need AC power any more. I did some calling around to see if I could get a 6.4 Volt heater made up, but that is pretty much unheard of in industry, and the manufacturers were going to have to charge me a huge amount of money to make one. Unfortunately, I can't use the same nichrome wire as Hippie because I really want the heater to be in the middle of the air stream and need it to be stainless steel. I also would like an internal thermocouple on the heater. This pretty much leaves me shooting for a cartridge heater. In other words, back to the original idea. After some thinking, I decided to use 12 V. I can use this batter pack:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3938

Conveniently, it has its own charge/discharge management card packaged with the batteries. The best news about all of this is that, at 75 watts, this device will take less than 6 amps. This is practical for both a wall power outlet and the average car circuit. Cigarette lighters in cars can, apparently, do at least 7.5 amps. In my mind, this kind of justifies the external batter pack and makes it more convenient to use with different power sources. It will also be significantly more stealth given that you don't have to hold the power source up to your face as well. Anyway, although I was forced to use 12 volts, it kinda worked out nicely.

Here is a first picture of the vape:



The body will be aluminum and measures 3.5"x2.25"x.75". I suppose I could get away with a really hard wood, but I want to try aluminum first. It is using a 2.5" x .375" cartridge heater at the moment. I am going to order one of these this week to make sure it is up to the job. The drawing has side covers on it. I used carbon fiber texture, but they might as well be wood. If it is aluminum, it will need something to insulate your hand from the hot metal. I haven't drawn the mouthpiece yet, but it will attach to the bottom of the main body. I am thinking of using magnets. That is kinda getting ahead of myself, though.

Sorry for not putting any updates up for a while, but, as you can see, I have been busy changing course. I am not going to abandon the last project, just taking a break. I may still decide to squeeze what I have now into an enclosure and go from there.

-skippy

 

[Hippie Dickie]

Don't forget the 75 watts just happens to be what the batteries (6.6 volts) are delivering into 1/2 ohm of 16ga nichrome 80 (24"). But that much power sure drives the heater to temp quickly - about 10 to 15F per second.

Is there that much difference between stainless steel and nichrome 80? Both have a melting point above 1000C, eh?

 

[skippymcware]

Hippie,

Whether or not Nichrome or Kandal or any of the other heater metals are food safe has been a constant study of mine since the beginning of this. I called so many companies in the heater industry. I have gotten answers on both ends of the spectrum and everything in between. From what I understand, the argument is that over time the metal begins to degrade and fatigue from all of the heat/cool cycles. This degradation allows small pieces on the surface of the metal to flake and break off. Apparently, old heaters have very pitted surfaces when looked at through a microscope. The question is, where did all of that stuff go? In our case, it would all be released into the air. I guess stainless steel is less prone to fatiguing and it doesn't contain nearly as much nickel or chromium, which are toxic to us. Just to make sure, I looked up their alloying elements on wiki. Nichrome is 80% nickel and 20$ chromium. 304 stainless steel has 10% nickel and 18% chromium. This is not so much my conviction, but it is the best argument I have heard so far. Not to mention the fact that it came from an engineer at sylvania/osram. A contrary opinion came from an engineer at tutco-farnam who told me that their heaters had exposed nichrome elements and that some of his customers, who he was unwilling to name or give me further details about, were able to determine that a short run-in process made them food-safe enough for their company.

All I can say is I will keep looking out for convincing evidence one way or the other.

 

[Hippie Dickie]

Thanks for the metal composition info. i shouldn't be so lazy, but it's a moot point for my design since the metal is all outside the glass that contains the airflow.

i saw more degradation of the 22ga nichrome 60 than i do of the 16ga nichrome 80.

Also, the feedback temp probe is about 1/2" away from the hottest part of the coil, which turns out to be 100F hotter than where the probe is measuring. so i'm seeing discoloration (oxidation?) at the hottest section of the coil.

 

[skippymcware]

I had to make a dimensioned drawings for some heater peoples, so I figured I would post it up here:

 

[stinkmeaner]

Skippy What made you change you mind from using one of the inline heat torches you had considered?

It seemed the cool touch inline heater would make an excellent (true) forced air whip vape possible, unlike the current one on the market which just use a couple of PC fans blowing onto a wide open glass tube.

 

[skippymcware]

The heat torches have two problems with them. One, they have exposed nichrome hetaing elements, so they are a health risk. Two, they were $175 and up.

 

[stinkmeaner]

In your research, did you check to see if this one has exposed nichrome wire?
http://www.farnam-custom.com/air_heaters/heatTorch050.php

It has an option for ceramic or mica series, and the rest is made of stainless. I wonder in the ceramic series embeds the nichrome in the ceramic. I guess I would have to call them to find out.

 

[skippymcware]

Yeah. As I mentioned in my recent conversation with Hippie, an engineer from Tutco-Farnam was the one who told me that all of their heat torch and cool torch products have exposed elements, but that one of their customers had managed to get it approved as food safe for their use. Apprently, they were "running it through a break in process" that involved running the heater at high temps and large air flows to burn any bad residue off. If you are interested, you can see the farnam products priced at

http://www.abbeon.com/store/categoryitems.cfm?catid=429

Hope that helps,
-skippy