problem with BT136 plz guide me urgent

Discussion in 'General Electronics Chat' started by all4here, Jul 23, 2010.

  1. all4here

    Thread Starter Member

    Jul 3, 2010
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    0
    i want to use the BT136 to control the bulb of 100W 220AC Volt.the problem is the bulb is dimming.
    i just want to ON/OFF condition.
    plz tell me how can i avoid the dimming of bulb.
    i want the full glow of blub
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Tell us a few things. Using a TRIAC is more trouble than a switch. Why do you want to do this? Do you want a remote control? If so, using a remote from X10 is inexpensive and effective.
     
  3. bertus

    Administrator

    Apr 5, 2008
    15,650
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    Hello,

    Is the circuit directly connected to the mains?
    Can you post a schematic?

    For more info on the BT136 and applications of thyristors take a look at the attached PDF's.

    Bertus
     
  4. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    i simple connect the bulb in the seris of the BT136 and trigger the gate
    and i can not design the proper circuit.the problem is that the blub is dimming and not full glow
     
  5. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    i simple proferm the practical.

    and i see this problem.
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    For isolation and driving the triac you could use a MOC30XX.

    [​IMG]

    The input is just a led, here driven by an open collector port.

    Bertus
     
  7. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    Why not use a relay? Simpler, easier to trigger, reliable. The only disadvantage is they are slightly more expensive.
     
  8. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    becoz relay Switching slow as compare to the BT136
     
  9. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    You're dealing with AC. Maximum of 50Hz/60Hz out of household mains. You don't need speed. Also, you can just turn on a relay and forget about it, a TRIAC would need to be continuously triggered.
     
  10. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    plz see the attechment

    i can not get the 220 volt acros the bulb.
    i get only 90 to 110 volt.
    plz solve how can i get the 220 volt across the bilb
     
  11. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    Is this 90 to 110 volts measured using a multimeter? True-RMS or averaging? AC or DC mode?

    If you have an oscilloscope... be very careful, set your scope probe to X10 mode or you could blow it up, and measure the waveform. Post a pic here.
     
  12. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0

    yes i have measured through multimeter.and this is AC.
    i do not have a oscilloscope.
     
  13. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    I'm placing my bets that the TRIAC is only conducting forwards/backwards, or only half the time (like at the peak of the waveform.) That would explain the drop in half supply voltage. Unfortunately it's difficult to prove without a scope. When the circuit is off, is the TRIAC cool? That is, not burning hot, it is OK to be slightly warm. If it is very hot some other factor is in effect, it might not be getting turned on all the way (which can happen with SCRs, not sure about TRIACs.)

    You haven't answered whether you have a true RMS or averaging meter. The averaging meter's voltage will be incorrect for non-sinusoidal waveforms (like the one I described), so you would expect to get less than half the supply by quite a few volts. Your meter is probably averaging if it cost less than $60, it will usually mention true RMS on the case.
     
  14. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I see the schematic in post #10, but there is no information on how the pulse it generated and waht polarity it has.
    Did you have a look at the PDF I attached about the triac applications?
    There you see there are 4 quadrants of triggering the triac.
    The circuit with the MOC optocoupler will take care of that.
    The only thing you have to do is activating the led to trigger the triac.

    Bertus
     
  15. all4here

    Thread Starter Member

    Jul 3, 2010
    31
    0
    plz tell me about the opto driver circuit

    which we use to drive the BT136 as ON and OFF switch


    MOC3020 or MOC3041 ?
     
  16. bertus

    Administrator

    Apr 5, 2008
    15,650
    2,348
    Hello,

    Both the MOC3020 and the MOC3041 will work.
    The only difference is that the MOC3020 is direct acting (it can also be used for dimming)
    and the MOC 3041 is waiting untill the next zerocrossing to activate the load (only for switching).

    Bertus
     
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