thyristor choice

Discussion in 'The Projects Forum' started by dexter001, Dec 28, 2010.

  1. dexter001

    Thread Starter New Member

    Dec 28, 2010
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    0
    I am making a laser door alarm in which whenever somebody breaks the laser path, a continuous alarm should be generated. Although the design which i used is working properly, the problem is that buzzer only beeps when somebody breaks the laser beam and stops as soon as the laser beam falls on the phototransistor again.
    A thyristor can be a perfect choice for solving the problem. But I don't understand how to choose the correct model of a thyristor for a particular circuit (especially where it is used for latching)
    The circuit design is similar to what is given here:
    electroschematics.com/4929/laser-based-door-alarm ​
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Attach a schematic here so that we can see what your circuit looks like.

    hgmjr
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Never mind, I see you have supplied a link in your first post.

    hgmjr
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    You are missing a latching function in the design. The way it is working is the way the circuit you breadboarded was designed to work.

    There are probably some solutions that better suit your application at www.discovercircuits.com.

    hgmjr
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    A recent post uses 2N5060's to latch LED's & a buzzer. Buzzer was in anode ckt, reset by momontary interuption of + supply to anode. Look up Otaku, Latching LEDs question, Pg 6 & 52, Projects Forum
     
    Last edited: Dec 29, 2010
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