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Delay power cut when key is removed.

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  • Delay power cut when key is removed.

    Hello friends need help on a delay power cut when the key is removed i have checked this site http://www.astron.nl/~smirnov/poweroff.html

    but feel it is gonna smoke up things cause ur connecting + and the - with a 50ohms resistor in between ....

    but im looking for something like that if anyone can help shall be good !

    mastero

  • #2
    I don't see it's connected between + and - .
    I see it's connected from one side to power-off button(that normally opened),and from other side connected to diode.Current flows through 50 ohm resistor only when you press that power-off button.
    Enjoint life!

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    • #3
      As I wrote to you in my e-mail, use 500 Ohms if you're worried. Or 150 Ohms 1W.
      Custom Linux system on an '89 VW GTI 16V Edition One
      Jogdial volume control, Sony joystick, IR remote...
      Used to be the fastest Linux on the road, until all these NOS types came along...

      Comment


      • #4
        well, it is connected to ground, but with a 5 megohm, and no, you shouldn't see smoke, unless you have make a mistake.. so, what smoked??

        Comment


        • #5
          He means the 50 Ohm one, the one that connects via the pushbutton. Use 500 Ohm instead.
          Custom Linux system on an '89 VW GTI 16V Edition One
          Jogdial volume control, Sony joystick, IR remote...
          Used to be the fastest Linux on the road, until all these NOS types came along...

          Comment


          • #6
            hey guys thanx for the postings.... yesterday i found this page on the net and its somewat like oms but i blew up the 5ohms resister actually it just gets heated up like crazy on a 12vdc 5amp adapter.

            Power-Off Time Delay Relay
            The two circuits below illustrate opening a relay contact a short time after the ignition or ligh switch is turned off. The capacitor is charged and the relay is closed when the voltage at the diode anode rises to +12 volts. The circuit on the left is a common collector or emitter follower and has the advantage of one less part since a resistor is not needed in series with the transistor base. However the voltage across the relay coil will be two diode drops less than the supply voltage, or about 11 volts for a 12.5 volt input. The common emitter configuration on the right offers the advantage of the full supply voltage across the load for most of the delay time, which makes the relay pull-in and drop-out voltages less of a concern but requires an extra resistor in series with transistor base. The common emitter (circuit on the right) is the better circuit since the series base resistor can be selected to obtain the desired delay time whereas the capacitor must be selected for the common collector (or an additional resistor used in parallel with the capacitor). The time delay for the common emitter will be approximately 3 time constants or 3*R*C. The capacitor/resistor values can be worked out from the relay coil current and transistor gain. For example a 120 ohm relay coil will draw 100 mA at 12 volts and assumming a transistor gain of 30, the base current will be 100/30 = 3 mA. The voltage across the resistor will be the supply voltage minus two diode drops or 12-1.4 = 10.6. The resistor value will be the voltage/current = 10.6/0.003 = 3533 or about 3.6K. The capacitor value for a 15 second delay will be 15/3R = 1327 uF. We can use a standard 1000 uF capacitor and increase the resistor proportionally to get 15 seconds.



            [ 10-31-2001: Message edited by: mastero ]

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            • #7
              Okay dude... you're gonna have to stop posting images that link to your hard drive.

              When our browsers load the image as "c:\photo.gif" it looks on our hard drive

              Now unless you've managed to hack into all of our systems, and upload this file to the root of C:\, this will never work

              -Miles
              Near Completion: Intel P166 MMX, 32MB ram, 13GB Hard Drive, Keypad, 4x40 LCD. Sproggy MK2.6 ATX PSU. Win98SE with Winamp and Mark Zehnder Plugin. (Web-site: very soon)

              Comment


              • #8
                OK sorry for that guys shall change all the pic posting to moi website .

                thanx buddy

                MAstero

                [ 10-31-2001: Message edited by: mastero ]

                Comment


                • #9
                  hey yeah ur write ..... i just moved the pic from moi hdd and no image on mp3 car ...

                  ok ok

                  Comment


                  • #10
                    better sorry for that dumbness

                    mastero

                    Comment


                    • #11
                      That's basically the design I started with, but then I realized I would need a friggin' HUGE cap to get a delay of minutes rather than seconds, because a standard transistor draws too much current. Hence the need for a MOSFET.
                      Custom Linux system on an '89 VW GTI 16V Edition One
                      Jogdial volume control, Sony joystick, IR remote...
                      Used to be the fastest Linux on the road, until all these NOS types came along...

                      Comment


                      • #12
                        ok oms ... i get it ...guess wat i finnally got the dely shut down to work .. like a fool i was cutting the direct +12 to the relay ;-)

                        Anyway it waork great thanx everybody .. for your time ..

                        shall make a more
                        mastero

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