Switches

Discussion in 'General Electronics Chat' started by koka, May 11, 2010.

  1. koka

    Thread Starter New Member

    May 3, 2010
    6
    0
    I have AVR : at90usb62 that receive USB voltage

    http://www.atmel.com/dyn/resources/prod ... oc7707.pdf
    I want to control with this AVR 220 voltage

    In the beginning I connect the relay to the AVR.
    In the moment that the AVR rise to 1 logy (5 Volt) the relay is open and the AVR stop to work

    Apparently the amperage that the relay need is bigger than the maximum AVR can give that is 40Ma
    After I decide to use a 2N2222A transistor that will cope with the amperage
    I connect the emitter to the ground
    The basis through a resistor of 1K ohm to the AVR and the collector to the input of the relay to 5 volt that is the voltage supply from the AVR that came from the USB
    Again all work fine until I rise up the leg to "1" logy then the relay is open and the AVR dead again
    Apparently the AVR is taken a lot of amperage I am surprise because the USB need to supply up to 0.5 ampere
    I put the diode across the relay to prevent reverse amperage for the transistor
    I was tried to use solid state relay and the work fine (I connect the relay straight to the AVR)
    The problem is that the solid state relay never completely disconnect therefore when the relay was disconnect the florescent hat was connected to the solid state relay continue to flash and this effect is not desirable and short the life of the florescent


    Therefore I beginning to search after mechanical relay that take less amperage
    I enter to Farnell and search relays, Power – General Purpose
    And I receive this table

    http://export.farnell.com/jsp/search/browse.jsp?N=500006+1002725&Ntk=gensearch_001&Ntt=relay&Ntx=mode+
    now I want to understand all columns in this table to find a relay that use less power that I have

    I will glad to receive help
     
  2. koka

    Thread Starter New Member

    May 3, 2010
    6
    0
    I search information about how to design the transistor that push the amperage ?

    If I will connect a DC – DC converter step up between the AVR and the relay, is it can help to solve this problem ?
     
    Last edited: May 11, 2010
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    also you should use caution when working with 220 voltage as this is dangerous and can easily kill you
     
  5. koka

    Thread Starter New Member

    May 3, 2010
    6
    0
    Thanks mcgyvr,
    Can you give the site that talk about or attached to the electrical sketch that you give
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    The attached sketch was from this site. Just continue to ask what you want to know from the schematic.
     
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