The Bud Toaster - (currently: Model 14, version 3)
- Thread starter Hippie Dickie
- Start date
. Additionally its successor, the MAX31855 is out of stock everywhere... grumble.
Whoa! nice find! i didn't realize the MAX6675 had a sequel - seems (quick read) to handle more than just K-type thermocouple, reports temps below 0C, much faster conversion 100 msec vs 220 msec, 32bit temperature reading instead of 16bit -- to show more error states. Samples are in stock.
Hmmm ... lower supply voltage of 3.3v -- that would be a problem, i need the 5v of the MAX6675 to keep the MOSFET gate voltage high enough to minimize resistance Rds-on.
i got MAX6675 samples a couple of times, but yeah, i'm paying $14 each in small quantities (10 at a time).
Hmmm ... lower supply voltage of 3.3v -- that would be a problem, i need the 5v of the MAX6675 to keep the MOSFET gate voltage high enough to minimize resistance Rds-on.
i got MAX6675 samples a couple of times, but yeah, i'm paying $14 each in small quantities (10 at a time).
Engy
engy
Ah, I didn't catch the supply voltage. You could always keep the uC at 5V, though, and level-shift the SPI signals between the uC and the MAX31855. Then again, minimizing the number of components is always good, so having all the peripherals use 5V is convenient.
This app note on level shifting is quite informative: http://www.maxim-ic.com/app-notes/index.mvp/id/3007
Guess I'll bite the bullet on these MAX6675s
This app note on level shifting is quite informative: http://www.maxim-ic.com/app-notes/index.mvp/id/3007
Guess I'll bite the bullet on these MAX6675s
well, the uC is okay down to 2vdc ... it's just the MOSFET that needs 4.5v or more on the gate -- maybe use a smaller MOSFET to control the larger MOSFET, or respecify that MOSFET if possible. A lower Vcc of 3.3v would make low dropout voltage regulator unnecessary -- the uC should crap out before the batteries discharge to below 2v each.
seems like parts specification is always a moving target -- or maybe i just move too slowly.
seems like parts specification is always a moving target -- or maybe i just move too slowly.
FungusAmungus1012
Member
Well it has been a long month of finding parts and figuring out a lot of new things, but my large, computer supply powered bud toaster version is finally complete. Not having much knowledge of electronics I decided I would take the more pre-made part route rather than build everything myself (at least for the first version 
). I took a 30A motor controller (way overkill for the project as it turns out) and connected it to a 300W power supply which was slightly modified to output 10A @ 12V (also overkill as it turned out). This was then connected to a Hippie Dickie styled test tube oven and all of this was put inside a wooden box. Here is a gallery of the device: http://fungusamungus1012.imgur.com/vapobox . Thank you HD for all your help and advice and for making such a kickass article that inspired me to make this.
). I took a 30A motor controller (way overkill for the project as it turns out) and connected it to a 300W power supply which was slightly modified to output 10A @ 12V (also overkill as it turned out). This was then connected to a Hippie Dickie styled test tube oven and all of this was put inside a wooden box. Here is a gallery of the device: http://fungusamungus1012.imgur.com/vapobox . Thank you HD for all your help and advice and for making such a kickass article that inspired me to make this.
Congratulations on your progress!
10A @ 12V isn't really overkill using my software ... during start up, it will be pulling 24 Amps from the 12v supply unless limited by the size of the power cable, which is not a problem in your configuration. So, also, the 30A motor controller is not that oversized.
One problem i had with the first PWM module i got on eBay was the potentiometer had a very small range of motion around the temperature of interest -- maybe 2% of the full range. And, eventually, that spot began to wear so the resistance was not consistent anymore. That motivated me to go with a custom controller design.
Do you have a Dremel and diamond bits to drill the glassware (vial and direct draw tube)? Suggestions: make a template to keep the bit from wandering when starting the hole (i prick holes in a thin sheet of copper from a hobby/craft shop) and submerge the surface of the glass under water for adequate cooling. i use about 15,000 rpm.
10A @ 12V isn't really overkill using my software ... during start up, it will be pulling 24 Amps from the 12v supply unless limited by the size of the power cable, which is not a problem in your configuration. So, also, the 30A motor controller is not that oversized.
One problem i had with the first PWM module i got on eBay was the potentiometer had a very small range of motion around the temperature of interest -- maybe 2% of the full range. And, eventually, that spot began to wear so the resistance was not consistent anymore. That motivated me to go with a custom controller design.
Do you have a Dremel and diamond bits to drill the glassware (vial and direct draw tube)? Suggestions: make a template to keep the bit from wandering when starting the hole (i prick holes in a thin sheet of copper from a hobby/craft shop) and submerge the surface of the glass under water for adequate cooling. i use about 15,000 rpm.
FungusAmungus1012
Member
Thanks HD.
Yeah the temperature control is not ideal at all. I only really use a fraction of a turn to get the desired temperature, and at startup I twist it about half way to get juices flowing and up to temp really fast, and then dial it down again. I don't really have a need for a fast startup since I'm not a frequent user, so I don't mind waiting a bit for it to heat up. About 4 to 6 amps is all that is really needed to make a home unit with about a 5-7 minute warmup period so I might try switching to a 6A max pwm and a digital controller. I'm also trying to work out a way to get a more portable power supply since lugging around a computer psu is not too ideal. I'm currently looking at laptop power strips or maybe some of those converters which allow you to use car appliances at home. Unit #2 will be more of a challenge, but that's where all the fun is anyway.
The main oven tube was cut with a dremel and a diamond wheel attachment and was quite easy (broke 3 tubes trying the score and lighter trick). I changed the inner tube to just being a smaller diameter test tube with one or two holes which are slightly above the bottom, and I cut the draw tube from the equation altogether. The smaller tube that goes inside is a bit trickier to cut because I didn't have any diamond drill bits so I had to use a carbide one I had (ruined 2 tubes until I got one done..). I'm going to buy the diamond bit soon since I might need a few more tubes and its just so much easier with one of those.
Now that I have the nichrome wire and test tubes I can make future versions a lot more simply without ordering a lot of things so I'll be trying new stuff pretty soon.
Yeah the temperature control is not ideal at all. I only really use a fraction of a turn to get the desired temperature, and at startup I twist it about half way to get juices flowing and up to temp really fast, and then dial it down again. I don't really have a need for a fast startup since I'm not a frequent user, so I don't mind waiting a bit for it to heat up. About 4 to 6 amps is all that is really needed to make a home unit with about a 5-7 minute warmup period so I might try switching to a 6A max pwm and a digital controller. I'm also trying to work out a way to get a more portable power supply since lugging around a computer psu is not too ideal. I'm currently looking at laptop power strips or maybe some of those converters which allow you to use car appliances at home. Unit #2 will be more of a challenge, but that's where all the fun is anyway
.The main oven tube was cut with a dremel and a diamond wheel attachment and was quite easy (broke 3 tubes trying the score and lighter trick). I changed the inner tube to just being a smaller diameter test tube with one or two holes which are slightly above the bottom, and I cut the draw tube from the equation altogether. The smaller tube that goes inside is a bit trickier to cut because I didn't have any diamond drill bits so I had to use a carbide one I had (ruined 2 tubes until I got one done..). I'm going to buy the diamond bit soon since I might need a few more tubes and its just so much easier with one of those.
Now that I have the nichrome wire and test tubes I can make future versions a lot more simply without ordering a lot of things so I'll be trying new stuff pretty soon.
Engy
engy
To drive the MOSFET, I'd take a look at something like the MCP1416 IC from Microchip. It can provide a lot more current than the output of a uC can. The gate capacitance of the MOSFET can reach 1000s of pF during high current switching and the 20mA or so output a uC is capable of will take a long time to charge it up to the desired V_GS. High current drivers reduce heating because they minimize the time the MOSFET spends in the high R_DS section of its operation curve for a given V_GS.
Its sensitive down to 3.3V logic, so its a useful chip for driving high current MOSFETs from low voltage control systems.
I'm getting all excited laying out this PCB!
Its sensitive down to 3.3V logic, so its a useful chip for driving high current MOSFETs from low voltage control systems.
I'm getting all excited laying out this PCB!
@Engy -- thanks for the suggestion -- i'm just kicking that can down the road for right now -- exercise for another time.
Meanwhile, i've taken a new approach on the battery box -- not wired yet, i've got to stare at this goat for a little while to determine if it's worth continuing the build, or if i should take yet another direction:
and, for scale against the cube:
The thin end will pull off to allow the batteries to be end loaded/unloaded.
And to think, this is the only two cell 26650 battery box in the entire universe. i may have to start a new division -- Hippie Dickie Power Systems -- just to get it out to all the peeps cursing the darkness (like i've been for the last several months) ...
Meanwhile, i've taken a new approach on the battery box -- not wired yet, i've got to stare at this goat for a little while to determine if it's worth continuing the build, or if i should take yet another direction:
and, for scale against the cube:
The thin end will pull off to allow the batteries to be end loaded/unloaded.
And to think, this is the only two cell 26650 battery box in the entire universe. i may have to start a new division -- Hippie Dickie Power Systems -- just to get it out to all the peeps cursing the darkness (like i've been for the last several months) ...
biojuggernaut
Snob
looks great HD. The sled or battery box is still very small bringing the entire mass of the BT up to most desktop units. Do you forsee a power adapter for the BT in its future?
biojuggernaut said:
Not that i would offer ... i used an AC adapter for about 8 years and all i can say is "no mas" -- batteries kick ass! However, any power supply delivering 6VDC to 20VDC at 5 amps (or so) could be used - if you put the Deans plug on it.
video? not until the batterybox is worked out ... first impressions, etc., etc.
by the way, that goat (in post #1009) fell over. damnitall. but i've already got a new design to fab -- maybe tomorrow after work.
by the way, that goat (in post #1009) fell over. damnitall. but i've already got a new design to fab -- maybe tomorrow after work.
VWFringe
Naruto Fan
don't make something you'll hate making (stick with your mantra to eliminate unneccessary production steps)
remember if someone buys a different brand they may have a few hundredths difference in diameter
about the video, get a girl to take a puff, if you're worried about advertising, but i don't think the manner in which you hit this thing will change much from now to production
starting to think you just think it's rediculous to stand in front of a camera and let everyone see you doing it, haha
have you thought about stacking them in a tube host?
remember if someone buys a different brand they may have a few hundredths difference in diameter
about the video, get a girl to take a puff, if you're worried about advertising, but i don't think the manner in which you hit this thing will change much from now to production
starting to think you just think it's rediculous to stand in front of a camera and let everyone see you doing it, haha
have you thought about stacking them in a tube host?
Alas, nothing new under the sun ... i've had to spend full time on redoing my business website and that has required spending several weeks studying the latest web development methodologies and such like: frameworks, jQuery, AJAX. And it appears that crap really doesn't apply to my situation. But it was useful to figure that out for myself.
i did manage to get my new development PC configured with my website code and SQL database so i can run the site locally, make changes, and not screw up my production site. This was a major milestone and has earned me some BT development time -- which will be Saturday.
i've got yet another new battery box design that i will cut and try and i'll post pictures if there is any progress. i sure hope so as this is the final missing piece of the puzzle.
And, of course, i've been continuously testing Model 14/Version 3/Unit 2 and it performs flawlessly. Still needs a few little tweaks. i'm thinking about adding several preset heat settings -- it's easy enough to adjust the temp, but having a low (say, 350F) and high (maybe 400F) starting point could be useful.
And as i mentioned in that "temperature mystery" thread in the General discussion section, the thermometer is functioning like a vapor gas gauge -- the temperature is held about 5F low due to evaporative cooling by the vapor generation, and drifts up to SETPOINT when the vapor is spent.
This is kind of cool, but i should probably fix that.
i did manage to get my new development PC configured with my website code and SQL database so i can run the site locally, make changes, and not screw up my production site. This was a major milestone and has earned me some BT development time -- which will be Saturday.
i've got yet another new battery box design that i will cut and try and i'll post pictures if there is any progress. i sure hope so as this is the final missing piece of the puzzle.
And, of course, i've been continuously testing Model 14/Version 3/Unit 2 and it performs flawlessly. Still needs a few little tweaks. i'm thinking about adding several preset heat settings -- it's easy enough to adjust the temp, but having a low (say, 350F) and high (maybe 400F) starting point could be useful.
And as i mentioned in that "temperature mystery" thread in the General discussion section, the thermometer is functioning like a vapor gas gauge -- the temperature is held about 5F low due to evaporative cooling by the vapor generation, and drifts up to SETPOINT when the vapor is spent.
This is kind of cool, but i should probably fix that.
Okay, VW, just for you -- i tried a little videoing. Here is 45 seconds (2 hits) in the middle of a session. Green LED (on the left) means you're good to take a hit -- that is, the measured temperature is at or above SETPOINT ... the SETPOINT temperature is 384.5F -- eh, it drifts up a little with a hit ...
Click to view video on my SkyDrive --- 45 seconds mid-session
Click to view video on my SkyDrive --- 45 seconds mid-session
Thanks for the vid, Hippie! After watching it I realize that the Solo takes a lot from your design. I hadn't really thought about it before. Of course your glass on glass bowl design will never have the problem of chipping and flaking, so thumbs up for the BT!! Keep up the great work.
While I haven't read through all the pages yet, this certainly looks like a well thought out project! I am looking to make something similar in form/function as the mflb and I'm just wondering about what your thoughts were on using your nichrome wire wrapped around a test tube with just a single powerex 2700 aa battery as the power source?
Thinking it may be too long of a heat up time for a portable, but the glass bowl design is really enticing to me. Anyways keep up the awesome and enlightening work!
Thinking it may be too long of a heat up time for a portable, but the glass bowl design is really enticing to me. Anyways keep up the awesome and enlightening work!
lesvape said:
The key word is "fully" -- while it takes only 25 seconds to go from room temperature (77F today) to 385F, it requires another 60 seconds to fully heat saturate the two borosilicate glass pieces and the bud inside, and begin to produce satisfactory vapor density. The vapor continues to thicken until after another 90 seconds when the vapor is pretty constant until spent after another 5 minutes.
After living with 4 times that amount of energy as the power source, i would not be happy with the operational profile. i've tried two 18650s to replace the two 26650s and the size/weight tradeoff can't compensate for the reduced number of sessions per charge.
i don't know(couldn't find) what the current delivery of those powerex AA cells is, but i really doubt it would be adequate (12 amps) for this coil heater: 24" of 16ga nichrome 80.
Thanks. How long is the battery life on the latest model? Don't remember seeing this in the thread, but how is it for liquids, and other non plant material? I think I may just break down to get this as its still one of the best on the market for my needs. I still take it price hasn't changed?
sorry, not yet on the market -- still have several months of field testing to do, and i want to tune the temperature control algorithm a bit more to eliminate overshoot and settling at startup.
Last time i measured battery life i was getting 9 sessions per charge, where each session is 7.5 minutes. i've been using a 6A charger which takes about 20 minutes to charge one cell.
i haven't tried it with liquids -- which are unattainium in my universe. But there will be a special glass piece specifically for hash and oils/extracts.
i'm still trying to determine final pricing, but right now i'm thinking it will be $500 for a complete setup with 10 year no-cost warranty.