1. What does SSTB mean? See our glossary of acronyms.
    Dismiss Notice

RBT Open Source build

Discussion in 'Upcoming and Unreleased Portable Vaporizers' started by RastaBuddhaTao, Jan 12, 2018.

  1. slatihe

    slatihe Well-Known Member

    Messages:
    197
    Thank you for changing you're mind @RastaBuddhaTao. And free when i offered to pay, is very generous!
     
    KeroZen, Shit Snacks and Jill NYC like this.
  2. P.A.M.

    P.A.M. Vapo Rising

    Messages:
    584
    Location:
    Planet Earth, North America
    I would like to sincerely apologies to anyone whom I may have offended by my questions or my opinions in this thread. It was not meant as an attack on anyone , was purely for the sake of better understanding this thread, equal opportunity and knowing what licensing or not it involved . I do not believe I have attacked or broken any FC rules in doing so.

    Thank you , RBT , for your kind and generous offer of free parts . I do appreciate it . Under the circumstances of your offer and how I am being perceived by some members , i would not feel ok or that it is right or fair to accept it . I would rather decline instead of feeling awkward and not fully enjoy it .

    I did remain quiet past few days after RBT asked me to stay and be positive or to refrain from posting . I did post one single sentence saying i agreed with @slatihe , I apologize for doing so and the backlash it created. Oh I also said i had a penis after RBT thought I was a girl due to my profile name P.A.M. My avatar does identify as male. I personally found my post hallarious but I guess not everyone shares my sense of humour, or my opinions for that matter . I respect that .

    Providing no one feels the need to instigate a negative response from my behalf, i will not post any further in this or any other RBT threads .

    I wish everyone a fun , safe and successful project . You guys and gals are my only vaping buddies , even the ones who don't see eye to eye with me. nobody I know in person vaporizes , not that haven't tried to make them to fuck combustion . Thank you again RBT , I congratulate you again as I previously have , for opening up and sharing your knowledge with other people . thank you to FC for offering us this great platform, please keep it fair and square for everyone .

    :peace:
     
    GreenHopper, AJS, boon and 3 others like this.
  3. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    Please do not feel dismissed.

    again, 4 "Master Builders" will be supplied this week. On 2/2 midnight any post made detailing ones qualifications and a brief summary of what design you will be working on will be considered for a kit.

    If your still interested then your post is still valid. Given the number of kits I believe I can but together with what materials I have there is a strong chance you will be selected based on your credentials.

    I tried to make this clear in my recent post. Sorry for the confusion, I hope you stick around and play with the RBT Open Source. More Vapes = Less Combustion
     
    GreenHopper, Gray Area, Boden and 6 others like this.
  4. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    Thanks to everyone for the interest.

    Here is the tentative list of builders and projects:

    Base kit - heater material, 14/19 mm joints, wire, components, screens etc.
    @Boden @oddjobold @Gator

    Heater kit - heater, female glass screen assembly, wire and heater mounting hardware with mouthpiece and screen set.
    @rz

    Zion wood body and heater set.
    @oddjobold @Lazy Lighting

    Milaana parts kit - all parts minus the wood
    @ZC @bellas

    Mi1 kit - all parts for a Mi1
    @Phenix has lead and has volenteered to make instructional videos. @slatihe and @P.A.M. @stickstones

    As @RastaBuddhaTao has done in the past, these kits will be provided free of charge in order to encourage more builders to use the HSA technology here on FC.

    If you are still interested please complete a contact form on the RBT www by 2/8 with your FC handle, name, address and a brief description of what you plan to build so that I can customize the kits to best suit your needs.
     
    Last edited: Feb 3, 2018
  5. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    Done
     
    KeroZen likes this.
  6. Phenix

    Phenix Well-Known Member

    Messages:
    253
    Location:
    Germany
    thanks for this awesome possibility @RastaBuddhaTao !

    Filled out the form lately, looking forward to getting in touch with you in person ;)
     
  7. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    @RastaBuddhaTao

    Will you be starting a project build thread for those of us making mods, or shal we just post here?
     
  8. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    My thought would be to post everything here as the power of open source is the sharing of information. This thread should be focused on the learning and discovery of the prototyping phase. I will leave it up to the mods as to when a design warrants its own DIY thread. I believe it is very much a willful participation here if one wishes to share they can share or just lurk if just following along is your thing. Logistics aside as long as the designing, testing, safely failing, discovery, improvement, redesign and proof of kill is shared, the goal of HSA proliferation will occur.
     
  9. Stu

    Stu Maconheiro Staff Member

    Messages:
    9,174
    Location:
    southeast of disorder
    When there is a DIY design that is available for sale to all, then I think it would be appropriate to start a new DIY thread. In the meantime, I've moved this thread to the Upcoming and Unreleased section as it is more appropriate here given the direction of the thread.

    :peace:
     
    GreenHopper, Shit Snacks, ZC and 3 others like this.
  10. rz

    rz Well-Known Member

    Messages:
    188
    @RastaBuddhaTao Thanks! I'm looking forward to playing with those! :)

    I plan to experiment with controlling power delivery to the resistive load. I also want to test how it behaves with the battery protection circuit I'm currently using.

    Since this project is still open-ended, I'm not sure if it'll end up incorporate existing drivers like the DNA boards or end up with something else a little more customized, or a mix of this and that. Maybe a few different versions? If it does end up with some electronics of it's own, which may need some protection, I'll start some relevant discussion based on the limited experience I have.

    After some research, I have incorporated over-voltage, under-voltage and over-current/short circuit protection into once of my recent boards, based on this S-8252.

    The current detection on this chip works by monitoring the voltage difference between VSS and VM - the voltage built up on the control MOSFETS, so choosing the right transistors is critical. Two transistors are needed for all the features to work properly.

    I (finally) found some that look great for the job, and they seem to be working well in my (real world usage:D) testing so far.

    These little puppies (IRLHM620PBF) run at about 2.5mOhm.

    This is for a 2S battery pack, with a nominal voltage of 7.4V.

    Looking at 15 Amps as a starting point for maximum current, thats ~110Watts. Actual delivered power is a bit less due to losses here and there, so lets call that at least 80 Watts deliverable.


    15Amps x (2x 2.5mOhm) = 0.075v = the voltage drop on the two MOSFETs at 15Amps.

    I currently have the S-8252AAO variant with with over-current detection at 0.2V on the MOSFETs and short-circuit detection at 0.5v resulting in about 40A over-current detection (8ms window) and 100Amp short-circuit detection (280us window).

    The thresholds can be changed by chip variant selection (ideally, when available), mosfet selection (RDS dependent), or lowered by adding series resistance to the MOSFETS. In my case, adding 5mOhm would halve those thresholds.

    Ideally we'd like the threshold to be just above what we need - in the example above, 15Amps, however we need to leave some(??) headroom. For instance, If the load wants to draw a lot, and we use PWM to tame it, we have to watch the peaks, not the average. 8ms should be enough time to tame detection if PWMing above a few hundred Hz though. With my IH experiments, I only PWM at ~10s of Hz and a hungry IH easily tripped my circuit while PWMing with the 0.2V detection threshold, So it works! :D - but some headroom IS needed. I tamed my IH down a bit to suit the protection by removing some capacitance.

    These are some of what I'd like to play with for this RBT project - driving a resistive load by either directly PWMing the heater element via some MOSFET at some frequency (maybe with some choke or capacitor - basically a noisy DC/DC converter, which may just be suitable enough for the application), or by the use of an integrated DC/DC converter that runs at a few hundred Khz with low ripple and probably a bunch of extra bells and whistles ( who doesn't like bells and whistles?:D ), and how all this behaves with the battery protection I've got built up already, making any necessary modifications.

    Below is the current design I'm using. It has not been extensively tested in an anti-blow-up-your face lab cause I don't want to blow up my face and don't own a lab as extensive as I see fit, but I do what I can. I'm putting this out there cause well, I don't want anyone to blow up their face:freak:. If anyone sees anything wrong with this design, plz discuss. Otherwise, feel free to use I hope it saves your face :D

    !!! DISCLAIMER --- THE FOLLOWING CIRCUIT MAY BLOW UP IN YOUR FACE - USE AT YOUR OWN RISK !!!

    [​IMG]

    Board layout is a separate discussion, as is battery charging..
     
  11. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    Thanks @Stu that sounds perfect!

    Wow @rz !!! I am a mechanical engineer but ran hardware and firmware teams in India so I know enough to be dangerous lol. Everything you said seems sound to me but someone like @KeroZen or other electrically minded people should take a look.

    Hopefully someone will take a 555 timer and make a simple adjustable PWM board as it might be small enough to fit into the Milaana electronics cavity. Dave at Mist and I have discussed it in the past. Or the poor man's version, a voltage regulator to set constant current. This is super inefficient at the regulator "burns off" the peak to get to constant voltage. Could work with a two battery set-up?

    Other ideas... LED buttons or LED imbedded in the wood such that it lights up the female glass. Did a prototype on 2015 on the early Milaana days. CAUTION: ensure that the buttons are rated for the voltage, current, at required duty cycle / life.

    https://m.ebay.com/itm/Mini-12mm-12...h-Button-Switch-For-Car-Boat-US-/162823591348

    Have also thought a hole drilled for a stir stick would be cool in Milaana. You could have an o-ring fit so it didn't fall out.

    I have a feeling some serious Highdeas are about to drop?
     
  12. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    Other than the fact there is no ground in this application (should be batt+) I see nothing inherently wrong.

    Current flowing through a switch is a bit dodgy. Adding a N channel mosfet with a 15k resistor bridging the gate and source and triggering with the switch will last a lot longer.

    https://www.mouser.com/ProductDetai...nTt6vbmGP8qGJwgXP_HgL3JIHeQ8BPowaAl44EALw_wcB
     
    Last edited: Feb 3, 2018
  13. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    Yes, thus the disclaimer to ensure the switch is robust enough for the application. The nice thing about using a MOSFET is that you can ise a small, light duty button. This opens up tons more options for buttons given that the MOSFET is taking the brunt of the load.

    The button in #rbtmilaana has been endurance tested in an over voltage situation for the equivalent of 5 years of heavy use without failure. Only one button in the field has failed in the last two years which was most likely a manufacturing defect. Provided adaquate factor of safety is applied, a direct contact switch is a reliable solution. It's a matter of a cost benefit trade-off for a given design.
     
  14. rz

    rz Well-Known Member

    Messages:
    188
    I'm all for a PMV and costs can definitely be cut on control and feedback features though preferably not on safety. Fortunately, it may not cost too much to be safe :)

    The BMS design above's BOM would be ~5$. They can also be found pre-built for a few $ on ebay/etc. and come in a variety of shapes and sizes.

    I'm sure once the heater designs settle and some power specs are clearer we could find a few relevant modules and parts that could be sourced online for a minimalist version (which can be a perfect solutions as shown by @Pipes ).

    As for regulation - I would skip linear regulation at all costs in high current applications. Either a manual (take what the battery gives approach) or a 90~95% efficient buck or boost depending on the battery configuration and heater resistance. (1S, 2S, or 2P ?)

    this search shows some relevant DC/DC step down converters. This one can provide up to 12A and can even be programmed to have under-voltage limit at say 5V which would prevent excessive battery drain (2S). If paired with a fast blow fuse, 'BMS' protection may even be skipped. Over-voltage can be achieved by using a proper designated LiPo charger as one should. I'm adding one or two of these to my cart to play with anyway.

    One of these DC/DC modules at around 10$ + PCB + etc BOM, electronics could be kept at 20~30$, maybe to pair perfectly with a $200 fancy button? :D

    On the other hand, a microcontroller and some basic noisy DC/DC buck design with feedback and some control could also be done for about that price.

    Integrating a USB charger would add 5~10$. I'm working on one that has a built in boost, battery balancing, and is very flexible like separate settings for input current limit, input voltage drop limit, charge current limit, battery fuel gage and some other features I'm not going to be using.. yet.. still have some layout to work on for it..

    Most of these would take someone time and set-up fees to build (I've been staring at every toaster over I see like hmmmm I wanna take you apart and melt stuff), so in the end it won't really be saving much $ compare to, say... a https://www.evolvapor.com/products/dna75 kind of board? We could call it a day and take a nap :D not what we're here for though? or maybe some of us. I'm sure a dna75 kit and guide would be awesome. I'd love one.

    @Boden earth is at the bottom right. The transistors disconnect the Battery negative terminal from the board earth. There are also 'high-side' protection chips. I started working on a high side implementation to avoid ground difference issues that would appear if using the device while charging and may wonk the balancing circuit out. I opted to stick with the low side one for now since i know it works to some degree, and concentrate on the charger. if the issue is significant enough (I don't think it will be an issue.. but compromises.. everywhere), I'll move over to high side protection..
     
  15. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    I’m not questioning your choices only trying to help inform the less informed.

    I wouldn’t worry about an over-voltage situation with battery’s as that’s basically impossible. Now over-current, that will mess a switch up fast.

    Keep flowing with the dao bro :D

    Shouldn’t the board ”earth” be bonded to the batt + ?
     
    Last edited: Feb 4, 2018
  16. rz

    rz Well-Known Member

    Messages:
    188
    @Boden load is connected between batt+ and earth. Earth is essentially the batt-, unless the BMS disconnects it.
     
    GreenHopper, vapen00b and Boden like this.
  17. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    Good stuff @Boden and @ZC. Just wanted to add RBT button detail for those choosing to use a simple direct drive circuit. Electronics can be scary for us mechanical folks.

    Hopefully later in the year we can start to put together design guidelines for each part / discipline. This will help future vapor makers get past the known and innovate. Stay Safe, Stay Grounded.
     
    vapen00b and Hogni like this.
  18. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    Gotcha. I generally design battery powered circuits with the “earth” +

    Using the GP as a source busbar is intriguing

    ________________

    For those who don’t design battery powered electronics, electron flow is from the negative side of a battery to the positive side.
     
  19. RastaBuddhaTao

    RastaBuddhaTao Well-Known Member Manufacturer

    Messages:
    843
    Hey @KeroZen and RBT Open Source vapor makers...can you share your plans for what project(s) you intend to work on? Ya'll gots to be havin' some highdeas, no?

    This will help me when preparing the material kits.

    @rz I believe folks like you and @KeroZen are the "clean sheet" vapor builders deep into the electronics. Some will opt to make their own body to house canned electronics and proven heater design (DNA with Figure 5 heater) and others would like a simple build kit with the difficult work done... thus the three categories of builders. I consider myself in the middle unless I consult my electrical engineer lol. Great to have you and @Boden along for the ride given your safety minded electrical engineering. It's easy to get these batteries into an unfavorable condition. Hopefully you or someone here will develop a dual and single battery solutions but given the development effort it might be easier to work with one of the canned solutions like a DNA chip set. In 2015 a DNA controlled proof of concept vape was constructed and performed well. It was the high cost of the chipset and added complexity that lead to Milaana. Now that RBT is outsourcing the woodwork, designs of added complexity are now achievable given an "off the shelf" power solution. I believe @Saltysusej69 has identified a few. One day I hope to be substantial enough to "blue print" a vape. Micro control allows for tailored power cycles like the CCW mode on my Vaporesso Revenger.

    The power required is dependent on the efficiency of your device and if you plan to run a continually in (desktop mode) or intermittently (on-demand / portable mode). The power range of RBT tech so far has a usable range of about 25 - 50 watts for convection with 30-35 being the sweet spot. My guess is continually on mode would range from 10-20 depending on reserve capacity. This would likely reduce if using 14 mm joints. Given that the resistance is lower when the heater is cold, the in-rush current is in excess of 14 Amps for those spec'in' $200 buttons.

    ...one more add - the initial 3D printed Milaana melted the heater melted during extreme voltage testing. This was somewhat expected given that the heater and wires are near the plastic. With Zion a long length of heater wire is placed in the Inlet air path to cool it prior to passing through the plastic wall. There are several ways to allieviate the issue. One is pre-build heater assemblies could be used. Then a 1 1/4" hole X inches deep could be designed into the 3D printed model to accept the insulated heater module.

    https://instagram.com/p/Be0eTraBuUv/
     
    Last edited: Feb 5, 2018
  20. oddjobold

    oddjobold 510 Vaporist

    Messages:
    422
    I know originally i was going to make a DNA Zion. However its not really practical. I need something stealthy i can put in my pocket. Also the zion did not have a good place for the board. I hope if Ryan likes my plan i can swap to a Mi.

    Mi DNA:

    [​IMG]

    Not the most technical of drawings but hope it gets my idea across. Think this build is matched to my skill level. I would need a Milaana thats slightly wider at the button end to accomodate the board. I thought about side mounting it, but think this will look a bit rubbish.

    I would make the hole for the board with a drill and make rectagular with a chisel. The drill i can mark with tape to get the correct depth.

    I am looking to buy the DNA board with mounting bracket like this:

    http://www.modparts.co.uk/boards/52...356210303.html?search_query=Dna+75&results=49

    Could someone check my wiring diagram? Thats what i understand from this PDF.

    https://www.google.co.uk/url?sa=t&s...FjAAegQIBxAB&usg=AOvVaw2arQV-Y06aUtepUPmIffAD
     
    Last edited: Feb 5, 2018
  21. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    Most of the physical design will be dependent on the size of the heater/ stem assembly and it’s attributes, so that part will have to wait until I have it to measure and test. Thermal properties etc.

    Powering it with a DNA75 as I have a couple dozen. Thought about using a 75C but that seems unnecessary at this point.

    Wiring will be all silicone insulated 12ga silver plated stranded copper.

    I’ll custom make the cell contacts from silver plated copper

    I’m thinkin I’ll keep the 19mm glass as I want the herb basket wider than it is deep for more even heat saturation.

    That said, I may make it so a 14mm glass stem assembly can be swapped in and out for more versatility. Basically a mechanical hold down of the female connector vs glue.

    Need to see the parts before I decide.

    Parts I don’t need;
    Wood
    Wire
    Switch
    Battery contacts
     
  22. rz

    rz Well-Known Member

    Messages:
    188
    @oddjobold Battery and heater wiring looks good. The wire from just above B- (where a GND post is on the board) to the GND on the top left is not really necessary as these points are connected internally on the board.

    These DNA boards look pretty cool. They have a load of useful features, including reverse battery protection, and seem pretty straight forward to wire up. I think it'd be a cool project that almost anyone could build with the right kind of kit and instructions with basic electronic tools.

    A cheaper method with fewer features which seems to be used already are the integrated DC/DC modules.

    Here's a kit to get an idea (this ones sold out, but I'm sure others exist..)
    https://shop.findmyvapes.com/products/diy-okl-t20-box-mod-kit

    and a build video (not by me):

    Click to play YouTube Video


    If anyone wants to get started with builds like these and I'll do what I can to help with electronics.

    There are some features lacking from that module, like a built in USB charger. It may be feasible to build a ~minimalistic motherboard for that module, with just a few extra features. This is something I could maybe get around to but no idea by when. I'll be getting myself an assortment of modules to play with in the meanwhile :science:
     
  23. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    Since a OKLT20 needs two cells in series I would not charge them in a mod.
     
    KeroZen and rz like this.
  24. rz

    rz Well-Known Member

    Messages:
    188
    Not even with a designated 2S charger with relevant current limitations and an NTC for thermal throttling? built in balance charging? I'm not sure if there are other reasons not to.. ?

    I've found that 2S batteries stay pretty close even after a bunch of charges. I'd say with a decent pair of same-batch cells you could get away with no balancing and limit your charge voltage to ~8.2V either with a simple on board charger or a suitable external one, while charging externally every few weeks to get back into max balance.

    The advantage of adding a BMS circuit over, say, the built in over-current used in the OKL chips, is the per cell under/overvoltage protection. This may not even be a necessary addition with an on-board balancing charger.
     
    KeroZen and Boden like this.
  25. Boden

    Boden Aspie polymath

    Messages:
    399
    Location:
    In the shop
    Well yes you could add all that complexity and do it. Or... ;) you could pop them in a dedicated charger, pop some freshly charged cells on the mod and be on your way.

    I tend to avoid unnecessary complexity. Less to go wrong.
     
    Phenix, rz and asdf420 like this.

Support FC, visit our trusted friends and sponsors