LED glow when switch turn off

Discussion in 'The Projects Forum' started by libra, Oct 19, 2012.

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  1. libra

    Thread Starter Member

    Jul 27, 2012
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    Hello everyone,

    I have made LED BULB Circuit with turn on the 40 LED. Problem i am facing is that after turning OFF the the LED are glowing slightly which can seen in morning also. The Capacitor C2 is not discharged. I am post the schematics of the circuit.

    Diode= 1N4007 are used as bridge rectifier.

    Transformer is 220V to 12V

    Thank you.
     
    Last edited: Oct 20, 2012
  2. absf

    Senior Member

    Dec 29, 2010
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    What's the voltage across the + and - terminals of BR1 after the power is switched off?

    Allen
     
  3. takao21203

    Distinguished Member

    Apr 28, 2012
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    1. Where is the switch?
    2. LED to mains (but having an isolation transformer apparently).
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Put a 1K resistor across the the capacitor C2, it will discharge it when powered off.
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Did you miss the fact that there are 40 LEDs in series? I think 100k might be more appropriate.
     
  6. libra

    Thread Starter Member

    Jul 27, 2012
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    It is 60V.
     
  7. libra

    Thread Starter Member

    Jul 27, 2012
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    There is no switch, i install in blub holder.
     
  8. libra

    Thread Starter Member

    Jul 27, 2012
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    If i put the resistor R6 across the capacitor C2 (As shown in the attachment) the led are not glow (ON).
     
  9. libra

    Thread Starter Member

    Jul 27, 2012
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    Any resistor (20ohm, 100ohm,120ohm) i put the led do not glow
     
  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    You have stated that you are using a transformer of 230 to 12 Volts.
    Then you CAN NOT have 60 volts on the leds.
    The maximum voltage would be 12 * 1.414 = 17 Volts.
    There MUST be something different than you have given.

    Bertus
     
  11. libra

    Thread Starter Member

    Jul 27, 2012
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    Bertus please see the schematics. In cricuit is have put the capacitor of 250v. Thats why i am getting 60V. The capacitor is not discharged that why the led glows.
     
  12. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Even with a 250 Volts capacitor, it is NOT possible to have more than 17 Volts on it using a 230 to 12 Volts transformer.

    There MUST be something with the circuit , that you do not tell us.

    Bertus
     
  13. libra

    Thread Starter Member

    Jul 27, 2012
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    Hi,

    I have posted the schematics that i used. Before installation of transformer i check the circuit. Thats the only reason, and i do not discharge the capacitor. Other then that their is nothing i am hiding.

    Libra
     
  14. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What do you mean with " Before installation of transformer i check the circuit. "

    Do you NOT have a transformer now?
    Then you are on a dangerous path.

    Bertus
     
  15. libra

    Thread Starter Member

    Jul 27, 2012
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    HI,
    "What do you mean with " Before installation of transformer i check the circuit. "" .This means that i check the circuit is working, and the bridge i made is working or not. I have the transformer and i install in the circuit. if you did not trust me i will post the picture of circuit.


    Libra
     
    Last edited: Oct 20, 2012
  16. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I said to use 100k. That is 100,000 ohms. If you connect this across the capacitor, the LEDs will glow, and they will not glow when the power is turned off.
     
  17. libra

    Thread Starter Member

    Jul 27, 2012
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    Like this (which is shown in schematics). Like R6 or like R2.

    Tell me the watt of the resistor?
     
  18. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    See attachment. The resistor can be 1/8W or more.
    Are you sure your capacitor is only 1uF? If so, you can remove it and get almost identical brightness.
     
  19. Wendy

    Moderator

    Mar 24, 2008
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    Thing is, you can not have 60 V with a 12VDC transformer in the circuit. LEDs off mains is not allowed here. This is what Bertus is / has been saying. It is one of our major rules, and will not be violated lightly.

    C1 / R1 / R5 are only needed if you are trying to run this off of mains. I have to conclude that you are indeed trying to run this mess off of mains, and are trying to get around our TOS, and this thread will shortly be closed for violation of TOS. I'll give you a chance to convince us otherwise, then this subject is closed, and can not be opened in another thread.

    To the other members, please do not continue this until the OP comes clean. A transformer is not optional. If you want to redo the schematic to reflect a true transformer type setup we can continue, otherwise this thread will be closed.

    To be blunt, trying to get around our TOS deliberately is a major violation, and will be handled accordingly.
     
  20. libra

    Thread Starter Member

    Jul 27, 2012
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    yes i am using 1uf of capacitor.

    Bill_Marsden as told Bertus that i check the circuit before install a transformer because i made the circuit on veroboard, i have burned one transformer to make that circuit.About C1/R1 i am controlling the amps C1 is of 10V. It is not 400V or 300V capacitor in my case, i write in schematic wrong. R5 is used to reduce the current more because i do not need much light. My logic is this that if we are getting less current from the bridge i do not have to insert more resistor, that's why i used C1/R1/R5.
     
    Last edited: Oct 20, 2012
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