Connect with us

Connection knowledge

Discussion in 'General Electronics Discussion' started by Tommy8389, Mar 22, 2017.

Scroll to continue with content
  1. Tommy8389

    Tommy8389

    15
    0
    Mar 18, 2017
    20170322_123712.jpg
    Can someone explain to me in details how does this circuit will works. That one is npn transistor. The red wire from the collector is connectwd to pin2 (trigger).So when someone pass through the ir phototransistor and buzzer will sounds.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,401
    2,777
    Jan 21, 2010
    Do you have the schematic for the whole circuit rather than a photo of just a part of it?
     
  3. Tommy8389

    Tommy8389

    15
    0
    Mar 18, 2017
    20170322_161613.jpg
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,401
    2,777
    Jan 21, 2010
    There still just a part of it. But it's clear that your transistorthan has the collector and emitter back to front.

    If it works, this diagram is likely incorrect.

    It looks like something you drew from the breadboard, not the schematic you started off with.
     
  5. Tommy8389

    Tommy8389

    15
    0
    Mar 18, 2017
    It is because i accidently reversed the npn transistor and it working. So i dont knw why.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,401
    2,777
    Jan 21, 2010
    Did it work with the transistor around the right way?

    I'm not sure if you're saying that it only works backwards, it that it works both ways. There are several ways you could have made this mistake. I don't know, for example if you took the signal from the collector or emitter before you reversed the transistor.

    You also haven't shown me what this "trigger" is that this is connected to. I could assume it's a 555 monostable circuit, but I'd prefer you tell me rather than me going to the effort of describing how this works, and then finding out if something different.

    Please don't make this play out like a murder mystery. I'll tell you "who dun it" if you give me complete answers, not just teasing me with drip at a time responses.
     
  7. Tommy8389

    Tommy8389

    15
    0
    Mar 18, 2017
    My senior simply did it for me. So i dont know whats going on lol. Yes the ic is in monostable and the pin 3 is connected to relay and buzzer.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,401
    2,777
    Jan 21, 2010
    You still haven't answered whether it is working now or not. If it is then:
    1. you are fortunate that transistors will show some gain with the collector and emitter reversed, but they won't like a voltage across them higher than about 8V
    2. You have misidentified the collector and emitter.
    If it's 1, swap them around. If it's 2 fix your schematic. There are other options if it's not working now!
     
  9. Tommy8389

    Tommy8389

    15
    0
    Mar 18, 2017
    After 1 day of hard-worked finally found out why haha. The vcc is actually connected to collector. and the pin 2 is actually connected at the emitter. Because imy senior connect the transistor in reverse active mode. So it made me confused.Thank you anyway haha
     
  10. Herschel Peeler

    Herschel Peeler

    401
    65
    Feb 21, 2016
    Design 1139 b IR trigger.PNG
    Does this make sense?
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-