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Need help identifying a power regulator

Discussion in 'Troubleshooting and Repair' started by yerawizardharry, Mar 31, 2014.

  1. yerawizardharry

    yerawizardharry

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    Mar 31, 2014
    I have one of the below regulators that i used with a variable power supply with a 5.5mm plug and i need to get another one, unfortunately i do not have the skills to build one myself and i am having trouble sourcing one.


    Can anyone tell me what i should be looking for as a replacement?

    Thanks
     
    Last edited: Mar 31, 2014
  2. kpatz

    kpatz

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    Feb 24, 2014
    I don't see a regulator at all, just a circuit with a 15-ohm resistor, LED and that blue thing that looks a bit like a varistor (surge protector).

    What is its application? And what voltage do you put in and what do you get out?
     
  3. yerawizardharry

    yerawizardharry

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    Mar 31, 2014
    I got it in an electroplating kit years ago, it works as a cut out circuit, when the voltage is too high the led flashes. I used it with 1.5-9 volt via a variable power supply that plugs into it with a 5.5mm plug.

    Any idea where i could get a replacement?

    Thanks for your help.
     
    Last edited: Mar 31, 2014
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    what do you mean by that ?
    you have already said you are only using 1.5 - 9V ... it cant get higher than 9V

    there's only 3 components in it

    so what specifically is wrong with it ?

    do you have a multimeter to test the resistor ?

    Dave
     
  5. yerawizardharry

    yerawizardharry

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    Mar 31, 2014
    About tree fiddy.
     
    Last edited: Mar 31, 2014
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    For those of you without access to the special google translate service, the above statement can be translated roughly as:

    edit, and I have divined this:
     

    Attached Files:

    Last edited: Mar 31, 2014
  7. kpatz

    kpatz

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    Feb 24, 2014
    The key seems to lie in that blue part. Sounds to me like it is normally closed and it opens when there is a fault, and then the current passes through the LED and makes it light up.

    Maybe it's a polyfuse, also known as a PTC thermistor.
     
    Last edited: Apr 1, 2014
  8. davenn

    davenn Moderator

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    Sep 5, 2009
    Makes sense, its resistance increases with more current so current takes easier path through the LED

    Dae
     
  9. yerawizardharry

    yerawizardharry

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    Mar 31, 2014
    Would it be correct to assume that if it is a thermistor then the device would only be good as a circuit breaker / fault finder for a few uses and then be deemed unreliable?
     
    Last edited: Apr 5, 2014
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The risk is that if it is a PTC that eventually (probably quite quickly) the LED is going to be damaged or destroyed. This will mean that overloads are no longer indicated, however the circuit will continue to operate.

    The polyfuse (if that's what it is) may have a limited lifetime, and that will depend a lot on how much of an overload it gets.
     
  11. yerawizardharry

    yerawizardharry

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    Mar 31, 2014
    Even if the maximum voltage does not exceed 12v?
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Possibly. It depends on the rating of the polyfuse (if it's a polyfuse).

    What's the value of that other power resistor? And what is the load again? (I'll go back and check this, but if you haven't mentioned it, maybe you can tell us now).
     
  13. jpanhalt

    jpanhalt

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    Nov 12, 2013
    Neither Vishay nor Murata give any specification related to the number of resets. Presumably it is large, unless the over-current situation was severe enough to actually damage the device.

    John
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    OK, so it's designed for 5V. The thing that looks like a LED is possibly a "flashing LED" designed to operate from around 5V.

    If you operated this from 12V and drew too much current, tripping the polyfuse, you might kill the LED and possibly damage the polyfuse (*if* it's a polyfuse).

    The LED if it failed would not exhibit any obvious signs (other than not working).

    I'm not sure of the failure mode of polyfuses. I don't know if they can fail but still appear "normal"
     
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