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Motion detector circuit

Discussion in 'General Electronics Discussion' started by Tommy8389, Mar 18, 2017.

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  1. Tommy8389

    Tommy8389

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    Mar 18, 2017
    Motion-Detector-Circuit-Diagram.jpg
    Basically there are few questions i want to ask :
    1) For the transmitter circuit set the frequency to 5kHz?
    2) Is the capacitor (100uf) before the speaker is necessary?
    3)Is the capacitor (0.01uf) for the NE555 timer's pin5 is necessary?
    4) Does resistor is necessary to place before the collector of the phototransistor to prevent damage?

    Problems after i connected the circuit :
    1) The led is keeps turned 'ON' no matter what. Isnt it suppose to turn off when both ir emitter and phototransistor is facing together? Even i changed the reset pin to ground to reset the circuit. After that, i realized the NPN transistor and phototransistor is damaged i don't know why. :( The circuit connection seems no problem at all .

    Notes:
    I brought the ir emitter and phototransistor is both 940nm from KINGBRIGHT :D The picture is not very clear and sorry for my english haha
     
  2. AnalogKid

    AnalogKid

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    Jun 10, 2015
    2. Yes. It blocks the DC on the output signal from entering the speaker.
    3. I don't think so, but the guy who invented the555 says it is.
    4. No.

    1. The LED is flashing too rapidly to see, so it looks like it is on all the time.

    ak
     
  3. Tommy8389

    Tommy8389

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    Mar 18, 2017
    and isit possible the phototransistor emitter produces over voltage to the base of the npn transistor and destroy it? because my npn transistor damaged one time before and have to replace a new one :(
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    It's remotely possible. Placing a 1k resistor in series with it should eliminate the possibility without affecting the circuit substantially.
     
  5. Tommy8389

    Tommy8389

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    Mar 18, 2017
    Capture.JPG
    I tried to simplified the receiver section to this. So will it works more perfectly? i reconfigured the pin 6 and pin 7 to 100k and 100uf ( Will equal 11 sec when discharging). So, Is the wiring okay?

    I cannot find the phototransistor diagram so i used transistor to replace it. The base is the Ir receiver. And the ir transmitter circuit i will used back the same circuit. o_O
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    No, Look in the circuit in your original post and do what I suggested. I DID NOT suggest you remove R1 or Q2. edit: AND you changed the wrong circuit!?!?!

    Our understanding (and probably yours too) will be improved if you make your layout neater.

    Vcc and Rst in this case can be drawn at the top of the chip. Likewise gnd and con at the bottom. Make your ground and Vcc rails straight lines across the bottom and top. Don't put bends in lines that don't need them.

    I'll try to do it for you to show you how it's done.
     
    Last edited: Mar 18, 2017
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Here's a better drawn schematic:

    555thing.png

    And immediately it becomes obvious that if you reduce R3 to the minimum you will fry the 555.

    And here is the solution:

    555thingb.png

    I will leave it to you to redraw the first one to make it easier to understand.

    Even if you can't read a circuit diagram, I hope you'd agree that the redrawn version is easier to follow.
     
  8. Tommy8389

    Tommy8389

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    Mar 18, 2017
    Ok thanks alot Haha. I just started in this electronic field. So there is still a lot of thing i don't understand. Thanks for pointing out my mistakes as well.
    Edit: Btw, can i use buzzer instead of speaker? if i use buzzer does that means my transmitter part can remove the timer 555 because no frequency is needed.
     
    Last edited: Mar 18, 2017
  9. AnalogKid

    AnalogKid

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    Jun 10, 2015
    You are correct, that is a very nice looking schematic. What software do you use? I'm shopping to replace an old friend.

    ak
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I use digikey's schemit. It's good for display purposes
     
    bushtech likes this.
  11. Tommy8389

    Tommy8389

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    Mar 18, 2017
    A002.gif
    I briefly build a stimulated circuit to test. But i found out that the output only produce voltage when the beam is not block. Can i use NOT gate IC at the output so that when trigger is "high". The output will be "high" as well.
    Notes: the output i want to use buzzer and relay. Thats means when something block between it, the output will be high.
     
  12. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    You could make a regular 555 oscillator and is the part of the circuit driven by the photo transistor to control the rest signal of the 555.

    This way the 555 will not issue until the been is broken. If you want to use a buzzer then the 555 is almost superfluous
     
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