The Bud Toaster - (currently: Model 14, version 3)
- Thread starter Hippie Dickie
- Start date
usr/share/vape
Well-Known Member
Bubar:
You didn't qualify your post as above. Sorry I offended you.
Hippie:
Great looking project. I've got a few Basic Stamps sitting around here unused. Aside from software issues, do you see any reason why that PIC wouldn't work?
cheers
You didn't qualify your post as above. Sorry I offended you.
Hippie:
Great looking project. I've got a few Basic Stamps sitting around here unused. Aside from software issues, do you see any reason why that PIC wouldn't work?
cheers
usr/ - i'm not at all familiar with the Basic Stamp -- it depends on what i/o the Stamp has available.
For an 8-pin chip, the 12F683 PIC ($1.35 in single quantities) has a lot of built-in peripherals and 6 general purpose i/o's. It's running at the 4 MHz built-in clock rate. i'd guess most of these micro-controller chips are plenty fast enough.
Saddle up the Stamp to a MAX6675, plug in a k-type thermocouple, and build a computer temperature controlled vape.
For an 8-pin chip, the 12F683 PIC ($1.35 in single quantities) has a lot of built-in peripherals and 6 general purpose i/o's. It's running at the 4 MHz built-in clock rate. i'd guess most of these micro-controller chips are plenty fast enough.
Saddle up the Stamp to a MAX6675, plug in a k-type thermocouple, and build a computer temperature controlled vape.
usr/share/vape
Well-Known Member
I've been looking into that 12F683. Interesting chip. The Stamp is only a sensible substitute if you already have one - they cost much more than $1.35 (but are very cool project chips). In a classic case of RTFM, I dusted off the Stamp docs. There's an example on how to interface a Stamp to a DS1620 temp sensor. I have a few DS1620's here. Did you use a thermo instead of a temp sensor for a specific reason, or is that what you had laying around?
cheers
cheers
The DS1620 only reads to 125C, which is only half the range needed for vaporizing, eh? And it reports its own temperature, not a remote temperature.
The MAX6675 reads to 1000C and has twice the resolution with 0.25C, and works with a remote thermocouple probe, and has cold junction compensation.
i selected the MAX based on the temperature range it handles.
i don't think the DS1620 can do the job.
The MAX6675 reads to 1000C and has twice the resolution with 0.25C, and works with a remote thermocouple probe, and has cold junction compensation.
i selected the MAX based on the temperature range it handles.
i don't think the DS1620 can do the job.
usr/share/vape
Well-Known Member
Ah, crap. I hate it when facts ruin a good theory. 
I hadn't considered the range issue. Guess I'm going to have to order some parts after all. Thx.
I hadn't considered the range issue. Guess I'm going to have to order some parts after all. Thx.
i've been using bare wire k-type thermocouple with 0.010" leads -- thinner leads are faster responding but more fragile -- i think these work pretty well, but they're all i've tried. i use teflon tubing to insulate the leads.
lead-free, RoHS samples at that.
hard to estimate yearly purchase quantity ... i can see the possibility of iPod quantities, lol.
hard to estimate yearly purchase quantity ... i can see the possibility of iPod quantities, lol.
usr/share/vape
Well-Known Member
Hippie,
Please check your hotmail....
cheers
Please check your hotmail....
cheers
Done. Answers sent.
Nice work, Bubar
i think i was too quick to blame the voltage regulator chip of failing ... the same symptom recurred, but i just let it ride and the vape continued to work okay, even though the blue LED would go out when the green LED came on.
So, anyway, i opened up the vape to do an inspection of condition and noticed the ground lead on the cable going to the user control panel was loose. And the + lead of the battery cable was loose. Resoldered both these and things are back to normal.
i think the real lesson here is that heavy current flow (>3 amps) eats the wire -- this refers to the battery cable, not the control panel cable.
So, anyway, i opened up the vape to do an inspection of condition and noticed the ground lead on the cable going to the user control panel was loose. And the + lead of the battery cable was loose. Resoldered both these and things are back to normal.
i think the real lesson here is that heavy current flow (>3 amps) eats the wire -- this refers to the battery cable, not the control panel cable.
Bubar
Well-Known Member
I'm having overheating problems with the transistor. I just had the solder melt and flow together on two of the pins, shorting the transistor. It was smoking after a second or two. How do you deal with the heat from the transistor? I am not at the pcb stage so I think I'll just get some copper and attach it to the back. Then hopefully I'll get a better heat sinkage. Or run a fan over it. Lol
my MOSFET gets wicked hot, but it doesn't get that hot. you're running 12 volts (?) vs my 6 volts - twice the watts dissipated, i guess.
You will have to put a heatsink on the chip. Both the PWMs i got before building my design had multi-fin heat sinks on the MOSFET.
Thanks for posting that information -- good data to ponder.
[on second thought] From a second or two? Sounds like a direct short to mega-amps. What kind of heater are you controlling? 24" of 16ga Nichrome 80?
[on third thought] i've been reading Wikipedia's article on PWM and the only time the MOSFET should be subject to heating from power dissipation is during the transition from off-to-on or on-to-off. So maybe reducing the frequency of the PWM in the PIC will help reduce the power dissipation.
i have an IR thermometer and i will try some experiments next time i have the Bud Toaster open for inspection and can get at the MOSFET and the PIC.
You will have to put a heatsink on the chip. Both the PWMs i got before building my design had multi-fin heat sinks on the MOSFET.
Thanks for posting that information -- good data to ponder.
[on second thought] From a second or two? Sounds like a direct short to mega-amps. What kind of heater are you controlling? 24" of 16ga Nichrome 80?
[on third thought] i've been reading Wikipedia's article on PWM and the only time the MOSFET should be subject to heating from power dissipation is during the transition from off-to-on or on-to-off. So maybe reducing the frequency of the PWM in the PIC will help reduce the power dissipation.
i have an IR thermometer and i will try some experiments next time i have the Bud Toaster open for inspection and can get at the MOSFET and the PIC.
Bubar
Well-Known Member
I used the 12v rail with the new 12awg power lines. A .75ohm element for 16amps. Holy crap. Instant heating. My nichrome was glowing orange. The bowl I loaded blackened in like 5s. I could stick my oily tube in there for a second or two, then just hit off of it. It heated way too fast, so I switched to 5v for 6.66A. It heats up pretty quick, but without any of the crazy glowing element. I'll probably stick with that or use a bigger element.. lol. Maybe 1 or 2 ohms hooked up the the 12V would be better... Using a room fan as a heat sink works pretty good.
So how do I control the set point with the buttons?
So how do I control the set point with the buttons?
Button control logic (remember, buttons activate when RELEASED, as a "de-bounce" technique):
Click Button ONE to increase set point by 10 degrees.
Click Button TWO to take the current coil temperature as the new set point.
Click Button THREE (the start button) to decrease set point by 10 degrees.
i wonder where you have the K-Type thermocouple probe located. It should be at the hottest part of the heater. Why isn't the PIC turning off the current? It must not be reading the heater temperature accurately.
You should read out the EEPROM from the PIC and see what values are being written there in the initial startup phase. You can show me what it says, if you want my analysis.
If the coil is glowing it is probably at 1000F (or more). You could use a thinner gauge nichrome to increase the ohms per foot. But 16 amps is not that much more than the 12 amps mine is pulling --- shouldn't be heating so fast. Although i'm using 16ga wire from the battery pack to the coil, so that could be a major factor limiting current flow to below the calculated 12 amps.
This PIC doesn't have enough I/O to plug into the computer ... or do you mean to just use the PC power supply to run the vape???
Click Button ONE to increase set point by 10 degrees.
Click Button TWO to take the current coil temperature as the new set point.
Click Button THREE (the start button) to decrease set point by 10 degrees.
i wonder where you have the K-Type thermocouple probe located. It should be at the hottest part of the heater. Why isn't the PIC turning off the current? It must not be reading the heater temperature accurately.
You should read out the EEPROM from the PIC and see what values are being written there in the initial startup phase. You can show me what it says, if you want my analysis.
If the coil is glowing it is probably at 1000F (or more). You could use a thinner gauge nichrome to increase the ohms per foot. But 16 amps is not that much more than the 12 amps mine is pulling --- shouldn't be heating so fast. Although i'm using 16ga wire from the battery pack to the coil, so that could be a major factor limiting current flow to below the calculated 12 amps.
This PIC doesn't have enough I/O to plug into the computer ... or do you mean to just use the PC power supply to run the vape???
Okay, yeah, some PC power supplies have a 5v plug on the back.
I added some more comments to my previous post.
I added some more comments to my previous post.
Also, i definitely need to diddle the duty cycle algorithm ... it is taking too long to come back up to set point when it drops below.
Although it appears to maintain set point better when i'm taking a toke. Seems to give the algorithm something to work against.
Although it appears to maintain set point better when i'm taking a toke. Seems to give the algorithm something to work against.
Also, the surface mount MOSFET is probably wrong for your 12v situation ... a through-hole MOSFET would let you clamp on a big-ass heat sink.
Hey! If you get that under control you will have the world's fastest vape. As fast as flicking a BIC!
Here is the new design -- going back to a cylindrical shape. It is 3" high by 1.75" in diameter. The top and bottom wood discs are 1/2" thick. Cherry wood and stainless steel:
This design has three stacked surface mount PCBs. The buttons are on the bottom ... at least until i turn it over once and dump the 400F vial into my lap.
This design has three stacked surface mount PCBs. The buttons are on the bottom ... at least until i turn it over once and dump the 400F vial into my lap.