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Lizard Brain Vape

Discussion in 'DIY' started by lizard.brain, Jan 30, 2018.

  1. lizard.brain

    lizard.brain New Member

    Messages:
    4
    Hey all!

    Ive always loved vaped, but nothing on the market tickled my fancy, and besides, I wanted to make my own :p

    Over the past month or so Ive been putting the base of my vape together. Still very much in test stage.

    Test Bed Specs

    Wanted a robust and powerful test bed that was over-designed for testing the mechanical section.

    Power: 18650 2S config. Designed around the VTC4 for a peak output of over 200W peak at nominal voltage.

    Control: Basic PID control using a K type thermocouple, not really impressed with heating coil temp sensing.

    Switching: Single power MOSFET in PWM (Currently rated at 60A, just for robust test bed). Wanting to avoid using switch mode PSU completely. [The second MOSFET is reverse battery protection]

    Storage: SPI bus has been broken out for possible SD card datalogging to tune the PID

    I was hoping to use logic level on the MOSFET, but it was running really hot, so added the dodgy signal amp to the back :p


    Mechanical

    Kinda just winging it, the glass is made out of test tubes, and the metal is just aluminum, plan to machine it out of SS once ive got a design down.

    The middle coupler holds the screen and will also have the thermocouple just under.

    PIX!

    https://imgur.com/a/fLQy4
     
    rz, JCat, Used2use and 6 others like this.
  2. Abysmal Vapor

    Abysmal Vapor Shaman of The Pyramid of Orlin'Malah

    Messages:
    2,868
    Location:
    7th heaven - 666th pit (EU)
    Love the name :D ! The concept looks cool too,where does the heating coil sit ? Outside the glass or in the airpath ? The construction reminds me of those which i dont know how are called but are used in brewery and are available in SS316. [​IMG]
     
  3. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    822
    Nice work on being safe and doing a laptop version to prove things out first.

    In a past life I worked it the food and beverage industry but used mostly sanatary fittings. Very steam punk looking... love it!
     
  4. lizard.brain

    lizard.brain New Member

    Messages:
    4
    Thanks :D

    The element will be on the inside, I want really fast heat up time, after a little testing yesterday, Im starting to think I may have to go down the boost converter PSU after all.
     
  5. Hippie Dickie

    Hippie Dickie The Herbal Cube Manufacturer

    Messages:
    2,519
    Location:
    where the Cube rules!
    i had a super hot MOSFET until someone schooled me on how to read the data sheet: i re-spec'd the MOSFET and raised the gate voltage to 4.5v and now it stays at room temperature ... my heater ribbon is .3 ohm with a 2S power pack, so pulling about 20 amps ... it gets to 400F in about 15 seconds, but still takes 60 seconds more to heat soak and melt the trichome wax ... nichrome 80 ribbon heater is outside the vapor path. i use a k-type thermocouple, too.
     
    JCat likes this.
  6. lizard.brain

    lizard.brain New Member

    Messages:
    4

    Im way to impatient to wait 60 whole seconds!

    :p
     
    Hippie Dickie likes this.
  7. Used2use

    Used2use Landrace racer

    Messages:
    399
    Nice project :)!
    Don't kow if i got the temp sens placing right - in the air stream under the screen?
    Well, i come more from the theoretic side but my :2c: on TC loops is to make them as 'short' as possible, meaning further away placing of the sensor from the heat source is like adding a spring to the loop wich results in a bit more oscillation range of the temp, that can't be compensated by PID values...
    I would only measure bowl temp for calibration, but It will work either way ;) have fun :)
     
    Last edited: Jan 31, 2018
    lizard.brain likes this.
  8. lizard.brain

    lizard.brain New Member

    Messages:
    4
    Ive had a stab at TC and PID before, I work in control systems :D

    Being dissappoited with a few heating element trials, I deiced to you know, actually check to make sure what Im trying to achieve (rapid > 2s heat up time) is even possible :p

    https://www.onenote.com/webapp/page...wogSI_94SDTvz3iwb-FGjk0&id=636530405444558717
    So it looks like heating the air seems reasonable, as we all know, that's good! So now focusing on the heating elements.

    Using a Halogen bulb : assumed all the mass was glass, 2.8s heat up time, at 200W, there is no halogens that fit my form factor / voltage at that power, so that's disappointing.

    Kanthal wire: about 2g of wire, what that works out in time of length, ill have to find my little scale to check, but seems rather high.

    Need a bit more playing.
     
    Used2use likes this.
  9. Used2use

    Used2use Landrace racer

    Messages:
    399
    Hm, looks like an Aromed bulb could fit, but it's only rated 50W@12V, so 200w in that tiny form factor is probably not usable in common halogen lamp applications, guess there are thermal limitations... - pretty shure u have already grilled a few :science: ? (most desktops use less peak power :evil:)
    Those halogen vapes always remind me of my first TC praktika at university :D.
    The calculations seem plausible, i love those classic engineering weapons: pen and paper :cool: (ok i'm still a mostly real paper dinosaur). Those 2,8s seem a bit 'sharp' calculated, with a few Kelvin overshooting needed i'd say at least 3,5s :p (as i am waiting 3 minutes for the plenty to load 20kJ heat for comparison :lol:)
     
    Last edited: Feb 1, 2018
  10. Squonk

    Squonk Well-Known Member

    Messages:
    18
    Hi lizard.brain. You assume 250 ml of vapour. Where does this come from?
     
  11. GreenCheese

    GreenCheese New Member

    Messages:
    7
    Honestly, you got a good idea running. Considering the cool name and design I think you should just do you. Looks great!
     
  12. mixchu69

    mixchu69 Well-Known Member

    Messages:
    1,872
    Good shit. I like all the innovation on FC these days.
     

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