Is it OK to use a zener diode without a series resistor in a transformer-less power supply?

Discussion in 'The Projects Forum' started by Michael George, Jun 13, 2016.

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  1. Michael George

    Thread Starter Member

    Feb 8, 2015
    52
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    In many circuits, I found that a resistor should be connected in series with zener diode to protect it.
    In this circuit, If a series resistor is used, The voltage of the load would NOT be the voltage on the zener diode. The load voltage would be the rectified voltage (230 * 1.414 = 325.22 V DC ). So, We have to use zener diode without the series resistor. But what about the protection of zener diode? The voltage across it is - 325.22 V DC. Is that ok?
    Would you give me part number of a zener diode that is suitable for this circuit?
    Thank you,
    [​IMG]
    http://www.homemade-circuits.com/2011/12/how-to-calculate-and-deduce-current-and.html
     
  2. BobTPH

    Active Member

    Jun 5, 2013
    782
    114
    In this case, the capacitor, C1 is acting in place of the series resistor you would normally find in a DC based zener regulator.

    Bob
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,031
    And transformer-less power supplies are expressly forbidden from discussion here per the terms of service.
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,716
    4,788
    As noted, discussion of transformerless power supplies is against the User Agreement, therefore this thread has been closed.
     
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