how to make timer 555 reset using PIR motion

Discussion in 'The Projects Forum' started by terabyte, Mar 3, 2012.

  1. terabyte

    Thread Starter New Member

    Mar 3, 2012
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    hi guys,
    i have a problem with my new project..
    timer has a reset, so how i can reset the led by using pir motion(after pir motion did not detect motion in 60 sec the led will cut)..

    may you guys can help me..:confused::confused::(


    terabyte:)
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Not sure we understand problem: My take is you have a 555 timer configured as a one-shot with a period of 60 sec. with a LED on output. If PIR detects motion within 60 sec. 555 should be reset or restarted?
     
  3. terabyte

    Thread Starter New Member

    Mar 3, 2012
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    the pir motion will reset the timer, so the led continue on.. after pir motion not detect any motion in 60 sec the timer will not reset and cut of the led..
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Dump the charge on timing cap. with a logic level FET [ BS170 RS 276-2074 ] or a darlington transistor [MPSA14 ] or 2 ea 2N3904's. If PIR output is suficient a single transistor would work asuming a 3 to 5 V pos. pulse output from PIR.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    I assumed that you already had an invertor between PIR out & 555 pin 2 to start initial timing, if not add.
     
  6. terabyte

    Thread Starter New Member

    Mar 3, 2012
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    can u show me that circuit,, i can't imagine ..
     
  7. soda

    Active Member

    Dec 7, 2008
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    Hi

    Here's a pir alarm circuit i build. The pir unit i used, contacts are close when there's no motion and open when it detect a motion.

    Hope this is what you're looking for
     
  8. terabyte

    Thread Starter New Member

    Mar 3, 2012
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    hi soda,
    thanks for the circuit, but how can i connect PIR motion with that circuit,,
    still confused,
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    We can supply a schematic if you supply some information: supply V for PIR & 555; model # of PIR or output specs; 555 or C555?; LED color? What do you have on hand toward the project?
     
  10. soda

    Active Member

    Dec 7, 2008
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    You have to open the Pir. Now you'll see 6 connectors.Two are for the power, then the other 2 are for the relay and the last 2 are for, in-case someone wants to alter your connections Check on the instructions that came with the pir and see if you can find the relay connectors. All you do now is to connect the pir to my circuit.

    I add the full layout of the pir alarm setup.Just follow the red lines on how to connect the pir
     
  11. terabyte

    Thread Starter New Member

    Mar 3, 2012
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    supply for pir and timer 555 is 12v
    model of pir is pr 14 im not really sure the model because get from friend..
    output pir in 4v to 6v... timer 555 led color blue,,
     
  12. soda

    Active Member

    Dec 7, 2008
    174
    13
    It would be good if you could show us a pic or circuit of this pir. Don't be shy.

    You can drop the voltage to as low as 6v if you like, no problem, but what you have to keep in mind is that the pir has a self testing period before it's ready for use. It's usually 2min. Place the pir so it shows to a wall, away from you. Now apply power to it and wait 2min and then move your hand in front of it. If it still doesn't work, there's a fault with this pir or you misplaced the connecting wires

    I'm saying it again, please show us your circuit
     
  13. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    This ckt , with out cap dump, has been in use since June 09, added second MPSA14 to discharge timing cap every time that PIR is triggered; once motion has stopped, 555 will time out in 60 sec. Transistor, R1 & R2 selection depends on PIR used. To use non darlington transistors, something like 2N3904's could be used; one as emitter follower to drive the other two, then would lower R2 to 2.2k.
    I think R4 & R5 should be interchanged so that with minimum setting of R5, pin 7 is not connected to + 12 V.
     
    Last edited: Mar 7, 2012
  14. terabyte

    Thread Starter New Member

    Mar 3, 2012
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    thanks you soda n Bernard, for sharing information .. i will try the circuit Bernard gave,,
    if it not success i will not shy to asking again,
     
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