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Articsimulator - Joyrider made of wood

Discussion in 'DIY Motion Simulator Projects' started by fredspeed, Nov 6, 2009.

  1. Frakk

    Frakk Active Member

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    Measuring the resistance of a diode will not give any useful information. If the multimeter has a diode check function on it, you can measure their forward voltage. This function can be used to check MOSFETs as well. You also need to remove components to properly measure them, since other components connected will affect your measurements.

    If you are to change any of the components, try to change the switching transistors that could cause shoot through.
  2. fredspeed

    fredspeed New Member

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    Thankyou as always! Just thought it was strange with that difference. Spending time struggling a little bit more with h-bridge while waiting for parts for Tim`s relay driver to try that too. Also struggle with mjoy, but posted about it on that topic.


    Regards Fred
  3. fredspeed

    fredspeed New Member

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    I found a short on my h-bridge. it was difficult to see but I spotted it using the diode tester on my multimeter. red and green leds light up when you use it in both direction in the area around the diodes close to the leds. I compared it with the working side, and that helped me to find the short. If I have one critic to this design, it must be the narrow space between the vide traces. When you fill up with solder to make it take more current, it is very easy to get shorts!
    No testing with motors until tomorrow, and ofcourse it might be some burned mosfets too :)
  4. fredspeed

    fredspeed New Member

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    Just to keep you updated: My h-bridge now seem to be working on both side after i repaired that short-cut :D

    To little time to spend on this project, and i am taking it slow and easy, trying not to mess it up. Now i am going to mount the pots properly, and then i hope to do some testing first with test-tablet, and then game, hoping it will take the current.

    After following egoexpress advice how to connect the motors, the peak current is much lower, about 30 amp starting both motors at the same time. Hoping for some good news later this week, and maybe even a video :hi:

    Regards Fred
  5. fredspeed

    fredspeed New Member

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    Seems like I now have a working dSMHB :yes: It did not blow up with me in the chair either, so for now I am going to use this for my seat-mover.

    I have not been able to test it properly yet, because I have some interference on the potentiometers. I know it is best to use audio-cables, and I do but still the numbers are jumping around on the lcd. Is there a limit how long they can be? mine are about 100cm. Does the thicknes of the wires matter? I might not have the best pots, but I have tried with different pots from 10k to 259k, and they seem to be ok when I use short cable. Any advices are Velcome.

    I might need some new pots, any recomandations? In that case I will need some more weeks to finish, but I am happy to say this is going to be a working seat-mover in the end!!!

    Regards Fred
  6. whaleman

    whaleman Member

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    That's fantastic Fred! Just minor pot problems and your ready to rock! Well done! :clap: Your progress gives hope for rest of us to get our sims moving.
  7. Frakk

    Frakk Active Member

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    You can use practically any pot. I would recommend better quality ones that last you longer and also less noisy. Single turn for easier mounting, and make some sort of slipping mechanism to protect them from damage in case they are driven out of range.

    Good Luck! :)
  8. fredspeed

    fredspeed New Member

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    I have 280 degree pots, and I use about half of the travel, but I must fins a way to get rid og that interference. Experimenting some more tonight. I used the same pots with mjoy, and as you know i run into some problems there also. The audio-cable I use is the type used for headphones, so they are not wery thick. I soldered wiper to the shield as Mindaugas recomended. Everytime I need to order I spend some more weeks finishing this, but i will try to find better pots. Speaking about mjoy, i just ordered a new atmega. they do not cost to much, and I believe my programming port is ok, so i give it another try with carefully setting the fuses as they should be :thbup:

    Fred
  9. fredspeed

    fredspeed New Member

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    :D The problem was cabling, yes... But it was between amc and lcd, no problems with pots at all :D

    Now I will go out shoveling som heavy snow, in a realy good mood!!! :cheers:
  10. fredspeed

    fredspeed New Member

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    Well, that was a bit to quick,,, that last post. It is some strange behavior here. sometimes it seems ok for a short time, but then suddenly the pot letters (right side of lcd) just count up and down and do not react to the pots as they should. The right letters are stable and react as they should running test tablet in profiler. Because my pots work ok sometimes i now believe it is something with my amc. What do you suggest exept my boards are haunted. Is it software or hardware, What part of amc could have some errors? I have 5 volts between ground an + at the pot-connection pins. And I also must tell you: this has been working ok before. When pots are not connected the numers seems to be normal (counting between 440 an 446)

    Fred
  11. fredspeed

    fredspeed New Member

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    Still stuck here with my feedback pot problem. I have tested also turning the motors with the potentiometer, and when the numbers on lcd jumps uncontrolled the motor also turns uncontrolled. An exampel: Sometimes when I start it all up, the pot seem to work ok, but after a short while it is going wild, or stops completely. The values jumps from low value to high without me turning the pot, and the motors seem to follow this uncontrolled values. Tried different cables and pots. This leads me to the conclusion that the disturbence or error is within the amc. So here is the questions i hope someone could help me with:

    Should I reprogram amc?
    should i replace the atmega?
    Is there any other part I should try to replace? (I have a complete set laying around)

    I have had this working before, so I believe the soldering etc is ok.

    I trust someone is willing to help, and believe me, I have never been this close to have a working seat-mover, and I think it will be finnished in a couple of years :lol:

    Fred
  12. Frakk

    Frakk Active Member

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    Yes, in that order! :)

    -Reprogram AMC - Free
    -Replace IC - couple euros
    -Replace everything - ~$200 (I mean buy a different controller)

    This is what I would do.
  13. fredspeed

    fredspeed New Member

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  14. fredspeed

    fredspeed New Member

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    OK reducing alternatives. I replaced my atmega. (was ready to program it, just to discover I alredy had done that before with another frequency :D ) But still the same numbers running wild when i connect pots. Could it be trimmer potentiometer? Guess this soon belong in the amc topic... ;D
  15. Frakk

    Frakk Active Member

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    The trimmer could cause that, but that would affect all analog inputs equally.

    I understand you want to complete it and not give up, just to say you did it. I have learned that sometimes the time and frustration is just not worth it in the end.. :)

    When you have had enough, just order 2x jrk 12v12 and your problems will go away. And you will get better quality motion too.
  16. fredspeed

    fredspeed New Member

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    I have all this parts laying around, so it wont cost me much to try, and I have enjoyed the learning process in it. But I know the price and where to order the pololu 12v12, so when my budget allows it I am pretty close doing it. I have also been reading the pololu topic.

    Fred
  17. fredspeed

    fredspeed New Member

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    I found this simple pot-test guide, and tested all my pots. It seems like the pots was the problem all the time. i just could not believe all my pots was bad, and it must have been bad quality.

    I will now order some new ones. Does anyone have a recomandation? (one turn pot) I use cheap pots from futurlec also connected to my mjoy, and they might have caused the problem I got there too.

    Fred
  18. EL-CORAZON

    EL-CORAZON New Member

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    Hi .How it is going with the simm? I have success on my poulolu driven chair now .rely good motorcontroler :)
  19. bsft

    bsft

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    Hello Fredspeed, heres a video of what I did regarding the hooking up of a single turn pot onto my latest frame


    Hopefully it helps. :cheers: David.