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uln2003 data sheet question.

Discussion in 'General Electronics Discussion' started by Dude22, Sep 15, 2012.

  1. Dude22

    Dude22

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    1
    Mar 30, 2012
    500ma limiter

    Hi, Is there any way to lower a 12 volt supply to 500ma when it starts around 10amps???
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Hey Dude, what do you mean "starts around 10A"?
     
  3. Dude22

    Dude22

    66
    1
    Mar 30, 2012
    I mean the original amperage is 10 and i want it to be 500ma
     
  4. Dude22

    Dude22

    66
    1
    Mar 30, 2012
    On this: http://www.datasheetcatalog.org/datasheets/120/489337_DS.pdf data sheet It says: "The collector-current rating of a single darlington pair is 500mA.The darlington pairs may be parrlleled for higher current capability" How would you do this???

    NOTE: In my other recent question I ask if there is any way to lower 10 amps to 500ma, If I can find a way for the uln2003's to allow higher then 500ma, this would be the better solution.
     
  5. CocaCola

    CocaCola

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    Apr 7, 2012
    Note that you can group them together for more than 500mA but the chip itself maxes out at about 1200mA total, so you can basically only parallel 3 outputs and get 1200mA per chip, might as well parallel all outputs at that point to better distribute the load across the chip... If you want to switch 10 amps you will need give or take 9 or 10 of these chips all paralleled together... You are far better off just getting a single larger package transistor that can handle the full 10A by itself...
     
  6. CocaCola

    CocaCola

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    Apr 7, 2012
    A circuit will only draw what it needs, if it needs 10A and you limit it to 500mA chances are it's going to not function properly...
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
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    Jan 21, 2010
    OK, now it's all merged. But even so, we still don't really know what you want to do.

    Perhaps if you tell us what it is that you want to do then we can help you.

    What you have done is come up with a few possible solutions and you're asking us about them without telling us what the actual problem is. Whilst we can address the things you have posted, experience tells us that to do so may leave you with something that won't work in whatever application you have.
     
  8. Timescope

    Timescope

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    0
    Aug 30, 2012
    I think he needs a current limiter circuit. 10 amps is not experiment friendly.

    Timescope.
     
  9. CocaCola

    CocaCola

    3,635
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    Apr 7, 2012
    My guess is that he is attempting to force something to operate at a lower current, and there is likely a better approach that can be taken...

    As I said previous a circuit only draws what it will need, excess available Amps from the power supply is rarely a concern of the circuit design... The only time a power supply that can pump 10A would NOT be 'experiment friendly' is if you have shorts and faults in your circuit that would smoke faster with the higher current... Other wise it's generally a positive thing as you it will be able to supply the necessary current for multiple things and don't have to worry about starving the circuit... Some medium sized audio amplifiers and things like motors can easily need that much current...
     
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    I too think he's asking for a current limiter.

    Anyone ever wonder why we spend better than 50% of our time playing mind readers? :rolleyes:

    Chris
     
  11. gorgon

    gorgon

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    Jun 6, 2011
    Yes, I think we all want to be soothsayers, and make it a competition between us to be the best. :D


    TOK ;)
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
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    Jan 21, 2010
    But (and this is not for CDRIVE's benefit) the load may actually require 10A startup current and so we need a change that will allow that current to be supplied.

    It may be as simple as a capacitor, but it may also require some pass elements to be looked at.

    Or it may be that the 10A indicates a fault in the load or it being miswired, etc.

    If we give the OP a solution to the wrong problem, it's not going to help (and may cause damage).
     
  13. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Honestly, only 50% of what we do here is actually giving advice, guidance and schematics. The other 50% of the time is spent thinking... "What the hell did he say?!?!".

    Chris
     
  14. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Ah, but there's the big ? Does anyone really know what the question is? I'm just going through the motions of that 50% I mentioned. :D

    Chris
     
  15. gorgon

    gorgon

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    Sometimes it is more like 90% thinking :rolleyes: And the rest is guesstimates :confused:

    Chris. I tried to make a humorous point, No offence intended.

    TOK ;)
     
    Last edited: Sep 17, 2012
  16. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    Take offense? Heck no. I too think it would be fun to have a contest. I'm semi retired but if I win I'll modify my all my company documents to include "& Psychic Medium". :p

    Chris

    Oh, I almost forgot.. I'm a big fan of old 50's - 60's vintage Si-Fi. Did you know that the Brits made a movie by the title "Gorgon"? ;) I think it ate London! :D
     
  17. gorgon

    gorgon

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    Jun 6, 2011
    Well, I took my alias from an old Norwegian children's TV show from the 60's. http://en.wikipedia.org/wiki/Pompel_og_Pilt

    Gorgon the janitor is one of the characters, and nothing to do with the Gorgon sisters from the Greek mythology.

    TOK ;)
     
  18. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Oops my mistake. That should be Gorgo that ate Ireland but fortunately didn't damage the pubs. :D Probably short for Gorosaurus, a huge theropod in the Tyrannosaur family, though the critter depicted looked more akin to an Apatosaurus on steroids.

    Uh, does anyone know where the OP went?

    Chris
     
  19. Rleo6965

    Rleo6965

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    Jan 22, 2012
    "He will be back" :D
     
  20. gorgon

    gorgon

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    Jun 6, 2011
    In a new and better version. :eek: Beware of the lightning :D:D

    TOK ;)
     
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