need help

Discussion in 'General Electronics Chat' started by melborn1010, Sep 6, 2014.

  1. melborn1010

    Thread Starter New Member

    Aug 28, 2014
    7
    1
    can any one help me for my project .

    Im using 555timer, relay ,PIR(motion sensor). When PIR sense a motion the circuit work and the 555timer trigger the 12v relay and when the motion is gone there will be a 4-5secs off delay for the relay to off.

    thanks in-advance :)
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    What help do you need?
     
  3. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    Post the schematics and your problem.
     
  4. melborn1010

    Thread Starter New Member

    Aug 28, 2014
    7
    1
    upload_2014-9-7_12-35-52.png


    in this case circuit . you guys think this circuit working? what the value of resistor to have a 3-4secs offdelay? and what is the polarity of the capacitor , becoz when i made the circuit i confuse what is the polarity of the electrolytic capacitor. and in my country the 0.01uf is rare here , what you guys think the replacement of the c5? and it is fine if i use 2n222 rather than c547b transistor? thank you guys :)
     
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,383
    495
    One thing you can do for the delay is to pick capacitor that you do have available, and then it is simple matter to calculate value of the resistor that you need. If the value of resistor is something odd, you just use combination of series and parallel resistors to get the value you need. This way you completely avoid the problem of finding capacitor.
     
  6. melborn1010

    Thread Starter New Member

    Aug 28, 2014
    7
    1

    what is the polarity marking (+)( -) of capacitor in this schematic?
     
  7. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,383
    495
    - leg of the capacitor is connected to ground.
     
  8. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    There are no polarized capacitors on that circuit.You can use electrolytic caps too.
     
Loading...