Help identfying a current regulator

Discussion in 'General Electronics Chat' started by dasitmane, Mar 31, 2014.

  1. dasitmane

    Thread Starter New Member

    Mar 31, 2014
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    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.


    Does anyone know where i can get a replacement?

    Thanks

    [​IMG] [​IMG] [​IMG]
     
  2. MaxHeadRoom

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    Jul 18, 2013
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    Pretty basic to build one.
    Is there a number on the blue item.
    It is not much of a 'Regulator'.
    Max.
     
  3. Dodgydave

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    Jun 22, 2012
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    looks like a resistor,led, and cap in a box to me...
     
  4. dasitmane

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    Mar 31, 2014
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    Hi Max,

    On the blue item i can make out what looks like

    0985 but it could be 0885 or c985

    (a triangle shape) next to the number "120"

    1336

    Yeah there is not much to it.

    If i were to google to try and find a replacment what would i be searching for?
     
  5. wayneh

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    Sep 9, 2010
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    I don't think that's a cap, but a MOV. I can't see what that box does except light the LED and make heat.
     
  6. dasitmane

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    Mar 31, 2014
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    I got it with an electroplating kit years ago. The led flashes if the voltage is too high and it works as a cut out circuit.

    Does this help?
     
  7. MaxHeadRoom

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  8. ian field

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  9. dasitmane

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    Mar 31, 2014
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    It is a varistor.
     
    Last edited: Mar 31, 2014
  10. odinhg

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    Jul 22, 2009
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  11. dasitmane

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    Mar 31, 2014
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  12. ronv

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    :DI think it's the picture and the part number.
     
  13. ian field

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    When I opened the link it said no image available.
     
  14. AnalogKid

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    Click on the datasheet link, and notice that one of the parts on page 2 is Type C985. Now where have I seen that before...

    Your device is a 15 ohm resistor in series with a thermistor that's around 4.6 ohms. When the thermistor gets hot from too much current, its value snaps up to over 1K (chart on p. 4). Compared to 15 ohms, that's basically an open circuit. Your device current now flows through the LED, illuminating it. When the thermistor cools off it returns to its original value like a self-resetting circuit breaker. A PolySwitch is a similar device with different metallurgy and switching characteristics.

    Note that these kinds of devices have a lifetime. Each overcurrent event changes their response. The cold resistance creeps up and the hot resistance creeps down, exactly the opposite of what you want. The same is true of MOVs, an overvoltage protection part. They offer real protection for only a few hits, and after 10 or so are pretty much worthless.

    ak
     
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  15. MaxHeadRoom

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    Or sometimes once is all it takes, if the Pulse Energy Rating (Joules) of the device is exceeded.
    Max.
     
  16. ian field

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    Apparently sidacs are all the rage nowadays - but once triggered they clamp at a low voltage and blow the fuse.

    You could always double up with MOVs as well - rate the MOVs so they just stop the sidacs from triggering - once they fail to do that (you know because the fuse blows) its time to replace the MOVs.
     
  17. dasitmane

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    Mar 31, 2014
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    Thanks for your reply. I have been using the device for about three years and assumed it still worked, are you saying that it was worthless after about the 10th time the LED flashed?

    What can i replace it with? Or would you say i don't need to replace it as it was worthless to begin with?

    It was only used to indicate if the voltage i was using was too high or if the items i was plating were in contact with the anode bar etc, wrongly connected to the tank, like a trip switch signified by the flashing LED..... i think!

    What other device / cut out circuit could i use to show that the voltage i am using is too high, i electroplate at between 1.5v-9v, depending on how big the part is. I use a standard variable power supply.
     
    Last edited: Apr 2, 2014
  18. ian field

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    At less than 12V - there probably aren't many MOVs about.
     
  19. dasitmane

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    Mar 31, 2014
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    MOV as in in Metal oxide varistor? What do you mean there are not many about at less than 12v? You mean not many manufactured? I know very little about electronics or their workings.

    Also is it correct what Analogkid said about this device only being of use for about ten times and then it will be unreliable?
     
    Last edited: Apr 3, 2014
  20. MaxHeadRoom

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    Last edited: Apr 3, 2014
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