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Tommy8389

Mar 18, 2017
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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.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Do you have the schematic for the whole circuit rather than a photo of just a part of it?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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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.
 

Tommy8389

Mar 18, 2017
15
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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.
It is because i accidently reversed the npn transistor and it working. So i dont knw why.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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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.
 

Tommy8389

Mar 18, 2017
15
Joined
Mar 18, 2017
Messages
15
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.
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.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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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!
 

Tommy8389

Mar 18, 2017
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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!
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
 
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