Switching light DC load usnig 220V signal

Discussion in 'General Electronics Chat' started by hazim, Nov 23, 2010.

  1. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    Hi all,

    I'm using a "big" 220V relays rated 10A with 3 contacts to switch a light DC load ON when line power goes off. 1 contact will fit my need, but they are available for about 3.5$ while the price of the 3 contact 220V relay I'm using is about 1$ only. Both are rated 6 to 10A. The load I'm using draws a current about 150mA or so... which make using such relays "odd" to use for operating them.

    I'm building things using this load that should operate when AC power goes off.
    So I think there should be a simpler way to do it.. maybe using a triac?

    regards,
    Hazim

    [​IMG]
     
    Last edited: Nov 23, 2010
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    What is the voltage and current of the DC Load?

    Until you have a thorough understanding of what you are working with, I'd suggest staying with the relay setup. Triacs typically are for controlling AC waveforms, while SCRs are typically for DC (both are called "Thyristors" though).

    Read the e-book, accessible through the bar along the top of the screen to get more comfortable with what you are trying to do.
     
  3. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    I've already read the e-book and read about thyristors. I know that SCRs can be switched on but not off when the gate signal goes off... if it works like that, it doesn't work..
    I said that the current of the load is 1bout 150mA, the voltage is 12VDC.

    Regards,
    Hazim
     
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Relay is the simplest way.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    If your control signal is 220VAC, then a contactor (relay) is the standard choice. If you are working with HVDC, then a voltage divider can be used to control a MOSFET to switch the LVDC load.
     
  6. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    if it already works and only costs $1, how simplier can it get?
     
  7. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    It's not logical to use a relay rated 10A with 3 contacts to switch a 150mA DC load... It's not a problem for me but there should be a more appropriate way to to that.
     
  8. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    one man's logic is another man's insanity.
     
  9. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Use a smaller 220V relay.
     
  10. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    13
    As you can get 1/8, 1/4, 1/2, 1, 2, 3, 5, 10, 20W and more resistors, and 6.3, 10, 16, 25, 36, 50, 63, 100V and more capacitors.. and more ratings for parts... it's better to use appropriated rated components... it's the same for that relay.. Anyway, I'll continue using the relay, the relay with 3 contacts which costs about 1$ where the smaller ones costs more, Bill.

    Regards,
    Hazim
     
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