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40-120V DC to 5V@120mA Voltage Regulator.

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by gasson, Oct 21, 2002.

  1. gasson

    gasson New Member

    Joined:
    Oct 21, 2002
    Messages:
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    Location:
    South-Africa
    Hi,

    I urgently require a 40-120V DC input to 5V@120mA Voltage Regulator. Can anybody help me please??

    Urgently required.
     
  2. mechie

    mechie New Member

    Joined:
    Sep 4, 2002
    Messages:
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    Location:
    Lincolnshire, England
    Problems with high voltages?

    Gasson wrote in a pm ...
    Buck regulator? I assume this is a conventional step-down series regulator?

    This circuit is dropping between 35 and 115 v across the transistors? is it possible that when you switch on one of the transistors sees more (possibly 120v ?) than it can cope with, resulting in destruction of the collector or base-emitter junction? Are the transistors rated high enough to avoid this?
    Or is there a current surge, charging a HUGE capacitor? (slowly increasing the voltage rather than 'banging' on would minimise both these effects).

    The above is guesswork as there is no circuit diagram to look at.
    Would it be possible to have two stages of regulation, the first dropping to maybe 30v. This could ease the stress on power-up.
     
  3. kinjalgp

    kinjalgp Active Member

    Joined:
    Oct 28, 2002
    Messages:
    1,851
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    Location:
    INDIA/USA
    Hi,
    Use Varistors to protect the Base-Emitter junction from blowing out. Also don't forget to use godd large Heat-Sinks for your power transistors.

    Kinjal
     

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