High Tech Fuse Block

Discussion in 'Vendors' started by craftycoder, Sep 19, 2012.

  1. RoTTe

    RoTTe n00b

    Joined:
    Sep 13, 2013
    Oddometer:
    4
    There are -in my opinion- other reasons for automotive parts -eg: maintenance issues-. For a pure resistive load -fairies world with unicorns running around - the worst case scenario: happy mosfet. This is neither real nor enduring. Nightmares occur -using a PWM with FAN load its a good example-, and if you filled the block with epoxy -who said replace the damaged part ONLY ?- murphy said if anything can go wrong it will go wrong.

    The repetitive changes for inductive loads (real world: aka all loads more or less) it's the worst case scenario for a power mosfet. The ruggedness comes from a part that assure you that you can put the mosfet on its limits without damage ( working only with "Absolute Maximum Rating" values usually comes to parts dying or degraded performance over the time ).

    NXP had some APPs notes about this, pulse and overshoot models:

    http://www.nxp.com/documents/application_note/AN10273.pdf

    If I'm wrong, please correct me (I love when I'm wrong and learnzt things). I think the whole problem comes from the electromigration and damage to the insulation layer(s) which occurs on the die when induced the worst conditions which usually ending badly if the mosfet die with a short drain-source (you can turn off the thing and so on...). it's uncommon to see an inmmediate change -like a cliff-, it's more like a down road... to hell -and fire-.

    The first rule about the fuses: you have a PCB to protect them. How many roasted PCBs with intact fuses ?. The AEC compliant parts, and specially the above mosfet with automotive grade comes with greater insulation layer -i hope :D- and some internally tricks that makes this things more reliable. When all manufacturers have a specific automotive grade costing twice, not worth the money when replace whole -unfixeable- part that worth hundred times more.
  2. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    I agree with you RoTTe. That is why I have the bag of new auto grade FETs on my desk (I had the wrong part number this morning actual photo below) and the intention to make use of them. I'm using a Transorb on each output to protect the power FETs from transients (which have worked well for voltage spikes up to 450V) and I also have dual pfets to protect the error amplifiers (current sense amps) from negative transients. I also encourage users to put diodes across inductive loads for safety but will they really do it? Somehow I doubt it...

    [​IMG]

  3. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    I am using that BUK7 rather than the BUK9 because the 9 has a VGS of +-10V and I am driving it at about +9V which seems like I am skirting a little too close to edge for comfort. It is 3.3mΩ RDSon which is twice that of the current FET but I may drop the shunt from 4mΩ to 1-2mΩ and end up with better performance, reliability, and temperature characteristics.
  4. RoTTe

    RoTTe n00b

    Joined:
    Sep 13, 2013
    Oddometer:
    4
    I think it's a wise choice -BUK9 is referenced as logic level MOSFET rather than standard level of BUK7, wide safe zone-. As always with these things: test, test, test!. I hate this feeling when you face a design and you have to take the good with the bad -all choices had its trade-off and none is perfect!-

    But the magic smoke is priceless :D Aside the money/time cost!
  5. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    I've seen my share of magic smoke. My reflow oven blew up last weekend (right before I was going to build a new PDU prototype) and I had to do a complete rebuild of all the oven internals... I had 120AC coupled to the my 5V rail (I was unaware of this) and was getting a strange error from the temp sensor (probably related to the AC but I am uncertain). I decided to touch the business end of the thermocouple and it gave me a heck of shock (I'm literally burning the wick are both ends for this project). In the body spasm the followed the thermocouple touched the oven case (earth grounded) and all the low voltage electronics exploded. Oops... The problem turned out to be in the OEM oven DC power supply (which has a dead short between 120VAC and the output of the 7805 5V DC regulator) and so it was not directly my fault. Still, I should have done a better job understanding the device I was repurposing. I rebuilt the whole thing with junk drawer parts and I once again have a reflow oven without any high voltage AC coupled in. I did mention that my tools are almost all homemade didn't I :deal

    Now that I have an oven again, I expect to be building up the new PDU MCU board tomorrow. A fresh design with some more safety equipment. :D

    The source of the magic smoke! That is what it looks like when you pull 1500W though a pin designed for 150mW. The thermocouple amp looked a whole lot worse. I tried to take a photo of it too, but I just couldn't get my camera to focus on it through the microscope...
    [​IMG]
  6. RoTTe

    RoTTe n00b

    Joined:
    Sep 13, 2013
    Oddometer:
    4
    Lucky you with 120VAC, try with 220VAC of Europe. But I've tasted worse. (Camera) Flash capacitors with ~300VDC -several times, I'm stubborn-. The worst by far was a neon inverter... the wire -rigid-, taped to table -cheap chinese tape- and the rest is up to your imagination.

    Good luck!
  7. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    We've reached 30% of our Kickstarter goal. Not bad for 5 days, but we still have a long way to go to reach our goal and see this project become a reality. My messaging has not been ideal. I think the video focuses too much on the smartphone angle and not not enough on the programming of the device which is where the real power lies. I was of the opinion that the programming would be hard to explain in 30 seconds so I might as well tease people with the fun stuff (the real time telemetry and interactivity) in hopes they invested the time to learn more from all the other available resources. It is not easy to confirm my hypothesis but based on the significant traffic and the comparatively few people who have decided to back the project I think missed the mark a bit. Monday morning quarterbacking...

    Anyway, thank you very much for your support and advice. We continue to need your help spreading the word beyond the hallowed halls of ADVrider. Your help will be vital in seeing this project become a product.
  8. EKinOR

    EKinOR Been here awhile

    Joined:
    Mar 25, 2012
    Oddometer:
    274
    Location:
    Central Oregon
    I'm spreading the word everywhere I can. This project needs to get funded!
  9. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    Thanks man. We can certainly use the help.
  10. beechum1

    beechum1 Grimace Soup

    Joined:
    Oct 14, 2007
    Oddometer:
    8,677
    Location:
    Not home in Tijuana
    Some of us have other priorities for the $ just now. I'm getting ready for Scotty Breauxman's Baja Rally. All my extra money is going to needs for the 3 weeks. I do need two if these, one for each bike, but ........$$$
  11. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    I'd rather have gas money and tires than one of these too. I get it! :deal

  12. klinquist

    klinquist ├╝bergeek

    Joined:
    Apr 7, 2008
    Oddometer:
    1,103
    Location:
    San Jose, CA
    Excited to see the kickstarter active - backed!

    Craftycoder, what happens if it's not funded? Will it not be produced?
  13. beechum1

    beechum1 Grimace Soup

    Joined:
    Oct 14, 2007
    Oddometer:
    8,677
    Location:
    Not home in Tijuana
    Not a matter or "rather," but I have to GET to the starting line first!!
  14. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    I don't want to know the answer to that question. I want to know the answer to the question about what happens after 200 lucky people have and love their Motobrain and 2000 people are knocking down my door to get their own.
  15. ironklad

    ironklad Adventurer

    Joined:
    Sep 14, 2010
    Oddometer:
    85
    Location:
    Herndon, VA
  16. 211

    211 Adventurer

    Joined:
    Mar 5, 2012
    Oddometer:
    77
    Location:
    Bellingham
    Will the app have the ability to override the screen dim and lockscreen timeout?

    Using my iphone handlebar case I could see using this app to monitor current draw or wattage as i'm riding (not always; but as accessories are added). Keeping the screen 'awake' could be a nuisance though.
  17. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    Indeed, I can control the nuisance factor.
  18. craftycoder

    craftycoder Motobrain PDU

    Joined:
    Oct 13, 2009
    Oddometer:
    2,336
    Location:
    Atlanta
    We are just about halfway through our Kickstarter campaign and have reached only 35% of our goal. I still need to find a home for about 125 more units.

    I can see that my messaging is flawed. I get a lot of feedback from people saying how needing to look at their phone while they are operating a vehicle is a dumb idea. No doubt, that is true. Thankfully the Motobrain is not about that. It is about allowing people to create highly customized electronic circuits in their vehicles without the need for a bunch of external bits and bobs (PWM drivers, constant current drivers, relays, fuses) or the knowledge of how to use them. The phone is a programming interface and real-time telemetry display. It is not designed to be the daily user interface. Unfortunately, that message is getting lost along the way. People who understand the product tell me it is an amazing tool that they really want. People who complain about it, complain about things that exist only in their imagination have have little to do with Motobrain. I'd prefer the complaints were relevant to the engineering, rather than just evidence of my incompetence as a marketer (a skill I hold no claim to).

    Anyway, it just means I need all the more help from you guys to help explain the value proposition to potential supporters so we can get this project launched. I know people will "get it" once they see it in real life. This first hurdle, of getting 200 in the field to spread the word, is proving more challenging than I expected though. So, this is a call to arms. I need your help again to spread the word and to help explain the difficult product message that this is not just some smartphone gizmo, but an intelligent PDU that uses a smartphone as a programming interface.

    If you want to see this thing become real, I need you to go out and evangelize. Tell everyone you know with an interest in a super cool gizmo for their bike, boat, or car to check out this awesome new smartphone PROGRAMMABLE PDU. Remind them that the cool feature isn't that you can control it in real-time from your phone, but that you can program it such that it usually doesn't need to be controlled, it just does want you want when you want.

    http://kck.st/17XjTrE
  19. dwoodward

    dwoodward Long timer

    Joined:
    Dec 1, 2005
    Oddometer:
    5,909
    Location:
    Pacific NorthWet, Napa Valley North
    See the problem? On one hand, it's a "real time" display, on the other you're telling them they don't need it. All of your videos show using a phone to make it do stuff.

    Perhaps instead say the phone can be used to program and diagnose circuits, push the "real time" stuff [further] into the background.
  20. beechum1

    beechum1 Grimace Soup

    Joined:
    Oct 14, 2007
    Oddometer:
    8,677
    Location:
    Not home in Tijuana
    To those who understand words and their meanings, there is no conflict. The option exists for both.