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[solved] Identifed a fried part on a Proto board. It was the Inductor. — Parallax Forums

[solved] Identifed a fried part on a Proto board. It was the Inductor.

DgswanerDgswaner Posts: 795
edited 2009-12-13 04:07 in Propeller 1
Before I replace a part on this board I just want reassurance that I have the right part in the schematic. from the Proto board documentation it look like that is the 1uH resonator connected just before the servo connections. And If any one could provide more info on the part it would be appreciated.

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"A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

DGSwaner

Post Edited (Dgswaner) : 12/12/2007 3:07:48 AM GMT
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Comments

  • Harrison.Harrison. Posts: 484
    edited 2007-11-30 08:59
    That's a 1uH inductor. You *could* replace it with a solid piece of wire if you can't find a good replacement inductor.

    Just beware that you may start getting brownouts without the inductor in place. This just means that your Propeller and various logic circuits may reset due to voltage drops caused by high current draw.

    EDIT: fixed bad grammar

    Harrison

    Post Edited (Harrison.) : 11/30/2007 9:06:08 AM GMT
  • Ken PetersonKen Peterson Posts: 806
    edited 2007-11-30 15:27
    How of all things did the inductor get fried? Your regulator is still ok??

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    The more I know, the more I know I don't know.· Is this what they call Wisdom?
  • Paul K.Paul K. Posts: 150
    edited 2007-11-30 15:55
    The same thing happened to me. Had a lead i clipped off fall on the servo pins. Didnt notice it. When I power the board up poof.
  • DgswanerDgswaner Posts: 795
    edited 2007-11-30 16:00
    Thanks for the help. To be honest I'm not sure. It happened when I was trying to connect my soon to be replaced Motor controller (4 relays). I was working out a truth table for the directions. when I saw a wiff of smoke rising from my board. I thought it was the regulator, as I didn't have the recommended series resistor. I know that it is 5v tolerant just not recommended. I'm thinking perhaps I set the board down on a screw or and alligator clip and made a direct connect the power source.

    The 5v and 3.3 regulators still work.

    Fixed: Grammer

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    "A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

    DGSwaner

    Post Edited (Dgswaner) : 11/30/2007 4:05:53 PM GMT
  • LeonLeon Posts: 7,620
    edited 2007-11-30 16:13
    You should be able to find a similar device, Farnell and RS stock them.

    Leon

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    Amateur radio callsign: G1HSM
    Suzuki SV1000S motorcycle
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2007-11-30 16:38
    'Sounds more like a fuse than an inductor! At a rather minuscule 1uH (according to the schematic), perhaps that was its real purpose! wink.gif

    -Phil
  • SapiehaSapieha Posts: 2,964
    edited 2007-11-30 17:47
    Hi All

    It function in both directions.
    Fuse and inductor
    5V regulator have its short fuse but if one short after inductor it is to smal to short it.
    And it blow upp.

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    Nothing is impossible, there are only different degrees of difficulty.

    Sapieha
  • DgswanerDgswaner Posts: 795
    edited 2007-11-30 18:54
    It was put there for a reason... I'm assuming. how important is it. I've never had to use an inductor when controlling servos. isn't that big capacitor there to stop brown outs when the current peaks is high.

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    "A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

    DGSwaner
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-11-30 19:28
    I put it there to provide the servos a bit of power isolation from the board's main supply. Inductors effective resistance increases according to a change in current, so when a servo quickly switches its current draw the inductor resists this and the servo is briefly "encouraged" to use the capacitor as it's power source instead. This helps to smooth the supply voltage on the Propeller side. Is the inductor necessary to use servos with the Propeller? no, but extra care will be needed to make sure servo power draw does not brown out the Propeller (ie don't have 4 servos switch from full counter-clockwise to full clockwise simultanously). Yes the inductor can be viewed as a 3A slow blow fuse, if you want to look at it that way (sustained current >3A will cause the inductor to fail, this value was empirically determined and is approximate).

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • DgswanerDgswaner Posts: 795
    edited 2007-12-11 20:52
    I tried to order a replacement part, and the part I got back says 0.1uH 10% inductor it's SMD but it's tiny compared to the one on the board. can someone tell me what I need to look for in the description to get the larger SMD version of this inductor. Or if someone could help me find the part number I appreciate it.

    the mouser part I ordered is 81-LQG21NR10K10

    Thanks

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    "A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

    DGSwaner
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-12-11 21:15
    The inductor on the current boards is Murata LQH32CN1R0M53, this part will change to Taiyo Yuden CBC3225T1R0MR for the next build.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • Fred HawkinsFred Hawkins Posts: 997
    edited 2007-12-11 21:47
    Dgswaner, can you retitle this thread to 'on the protoboard's inductor'?

    Post Edited (Fred Hawkins) : 12/11/2007 11:15:03 PM GMT
  • DgswanerDgswaner Posts: 795
    edited 2007-12-12 03:04
    Thanks for the info and especially the part number. I think for the size they are worth more than gold! .70 from digikey and 10 min. @ .35 from digikey but .70 is worth the main controller not browning out.

    Why am I changing the title to 'on the protoboard's inductor'? It was appropriately titled when I started the thread.

    how does that work for you!

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    "A complex design is the sign of an inferior designer." - Jamie Hyneman, Myth Buster

    DGSwaner
  • Fred HawkinsFred Hawkins Posts: 997
    edited 2007-12-12 16:31
    Dgswaner said...


    Why am I changing the title to 'on the protoboard's inductor'? It was appropriately titled when I started the thread.

    agreed, and now it's just·descriptive of the topic·for future eyes. Six months from now someone may want to know about what Paul had to say why there is an inductor at all.
  • JamesRonaldJamesRonald Posts: 39
    edited 2009-12-13 04:07
    Strange, I too just toasted L1 (shorted out the servo power pins with my new PropScope probe).

    I found this thread using search. I wonder why it does not show up in the regular forums listing as it was updated today.

    Anyway, thanks for the information Paul.

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    James Ronald
    My Robots

    Post Edited (JamesRonald) : 12/13/2009 4:14:25 AM GMT
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