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  • Convert a flashing signal to a constant signal?

    I'm trying to hook up my OPUS to my alarm system so that it turns on when I arm my car. I want to hook the turn on power line for the OPUS to the alarm light thats activated when the car is armed however, this light flashes on and off when the car is armed I need to make this into a solid 12v signal for the OPUS anyone know how I can do this?
    StreetDeck.com Developer (I am Chuck)
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  • #2
    The design will depend on how much current you can get out of this flashing signal and how much current you want out off the solid 12V.

    It also depend if the the flashing signal is 12V/open circuit or 12V/0V...or is it just flashing an LED?

    Give us more details.

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    • #3
      so when you arm your alarm you want your opus to shut down your computer
      and when you unarm your alarm you want your opus to power up?

      Comment


      • #4
        so when you arm your alarm you want your opus to shut down your computer
        and when you unarm your alarm you want your opus to power up?


        Yeah I think that make more sense

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        • #5
          check out this thread, especially the third post down

          http://www.mp3car.com/vbulletin/showthread.php?t=22682

          but this still isnt everything you need, you would need some way of making the flashing of the lights into just a single 12v 'punch'.

          Comment


          • #6
            and what kind of alarm?
            model and such or even better a link to the specs of it

            Comment


            • #7
              Thanks for the replys so far... I will be using a relay that will be open when the alarm is armed and closed when the alarm is closed. This should result in the OPUS getting the power to the turn on switch when unarmed. I hooked a voltmeter up to the charge feeding the lcd light. It is 12v -> 0v when its armed and flashing and 0v when its off so I wont need to covert voltage. The flash blinks every 2.4s.

              I know nothing about electrical engineering, but after a quick stop at howstuffworks.com I mistakenly thought I could just hook up a capacitor that would charge and discharge evenly through the cycling and result in a constant 12v signal. I bought a pack of capacitors and played fun games with electricity, but I can't get them to do anything cool.

              The alarm is the stock alarm on an infiniti G35 coupe. I looked at wiring diagrams and played with the wires on the Body Control Module, but nothing gives a constant signal when the alarm is armed, everything is flashing or serialized.

              Originally posted by BoraXP
              so when you arm your alarm you want your opus to shut down your computer
              and when you unarm your alarm you want your opus to power up?
              StreetDeck.com Developer (I am Chuck)
              Get StreetDeck at http://www.streetdeck.com
              The Official StreetDeck Forums have moved, please visit us at http://www.streetdeck.com/forum for official support for Streetdeck.

              Comment


              • #8
                Here are some schematics from the service manual for the alarm.
                Attached Files
                StreetDeck.com Developer (I am Chuck)
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                • #9
                  Originally posted by god_of_cpu
                  Thanks for the replys so far... I will be using a relay that will be open when the alarm is armed and closed when the alarm is closed. This should result in the OPUS getting the power to the turn on switch when unarmed. I hooked a voltmeter up to the charge feeding the lcd light. It is 12v -> 0v when its armed and flashing and 0v when its off so I wont need to covert voltage. The flash blinks every 2.4s.

                  I know nothing about electrical engineering, but after a quick stop at howstuffworks.com I mistakenly thought I could just hook up a capacitor that would charge and discharge evenly through the cycling and result in a constant 12v signal. I bought a pack of capacitors and played fun games with electricity, but I can't get them to do anything cool.

                  The alarm is the stock alarm on an infiniti G35 coupe. I looked at wiring diagrams and played with the wires on the Body Control Module, but nothing gives a constant signal when the alarm is armed, everything is flashing or serialized.
                  so you located the actual alarm unit and tested the voltages coming from it?

                  Comment


                  • #10
                    I tested the actual flashing indicator light at the top of the center console prior to the electronics to covert the voltage to the 1.8volts for the led. (see the first schematic) I don't think there is an individual alarm unit per say... Everything seems to go to the Body Control Module that has about 70 wires going into it controling everything that the car does. I tried tapping into some of the wires there, but couldn't find anything usable that was a constant signal when the alarm is armed or disarmed, it all seems to be serialized or flashing some how.

                    Originally posted by BoraXP
                    so you located the actual alarm unit and tested the voltages coming from it?
                    StreetDeck.com Developer (I am Chuck)
                    Get StreetDeck at http://www.streetdeck.com
                    The Official StreetDeck Forums have moved, please visit us at http://www.streetdeck.com/forum for official support for Streetdeck.

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                    • #11
                      trace the led back to the source
                      see if its connected to a timer relay or something
                      its probably not but you never know

                      Comment


                      • #12
                        Ok...

                        If you are tapping from the LED most likely its a 5V/0V cycle not 5V/open circuit.

                        You also need to determine if the signal is 0V/open circuit...this can be also the case.

                        The voltage will be also lower due to current limiting resistor by the time it get to the LED, 2V perhaps. How is the LED connected? signal/0V or +12V/signal? theres a big difference.

                        Try this circuit :

                        Put a small diode (1N4148) just after the output of alarm that connect to the LED.

                        A capacitor from the diode to the ground. A resistor across the capacitor.

                        The value of the capacitor and resistor is such that it cover the time when the LED is off. The diode ensure that the capacitor is only charged by the flashing signal and never discharged. The resistor does the discharging (try without the resistor first)

                        You should get a 2V constant across the capacitor/resistor if you get the values correctly. However you cannot get much current out of this circuit, as I said before there must be a limiting resistor in the alarm.

                        You must then convert this constant 2V into a constant 12V...more to come later...Im late for work

                        Hope I didnt confused you

                        Comment


                        • #13
                          Ricky327,

                          Thanks for the reply, I'm a bit confused, but much better off then I use to be. I am tapping the LED voltage before a circuit that looks to have just a resistor and disc capacitor. Before the circuit I get a 12v signal when the light is on and after its 1.8v both flash though. The flashing signal is generated by the Body Control Unit, which from what I can gather from the service manual is more a computer then simple a circuit board with 70+ lines feeding into it controlling everything from lights to the climate control system.

                          I'm not sure I understand by what you mean by signal in +12V/signal or 0V/open all I know is that when I hook up my multimeter when the light is on, I get 12v and 0v when its off. Does signal / open just mean whether it has / does not have continuity?

                          I shall put the circuit together when I go home today and play around with it. Thanks!

                          Also, on the capacitors I bought, there is both a voltage and a number in microfarads inversly proportional to the voltage. I know the microfarads is for the capacity of the capacitor, but why is there a voltage? I thought capacitors could take any voltage and would just fill up / discharge at a different rate depending on the current of what it is fed and discharged at.

                          Originally posted by Ricky327
                          Ok...

                          If you are tapping from the LED most likely its a 5V/0V cycle not 5V/open circuit.

                          You also need to determine if the signal is 0V/open circuit...this can be also the case.

                          The voltage will be also lower due to current limiting resistor by the time it get to the LED, 2V perhaps. How is the LED connected? signal/0V or +12V/signal? theres a big difference.

                          Try this circuit :

                          Put a small diode (1N4148) just after the output of alarm that connect to the LED.

                          A capacitor from the diode to the ground. A resistor across the capacitor.

                          The value of the capacitor and resistor is such that it cover the time when the LED is off. The diode ensure that the capacitor is only charged by the flashing signal and never discharged. The resistor does the discharging (try without the resistor first)

                          You should get a 2V constant across the capacitor/resistor if you get the values correctly. However you cannot get much current out of this circuit, as I said before there must be a limiting resistor in the alarm.

                          You must then convert this constant 2V into a constant 12V...more to come later...Im late for work

                          Hope I didnt confused you
                          StreetDeck.com Developer (I am Chuck)
                          Get StreetDeck at http://www.streetdeck.com
                          The Official StreetDeck Forums have moved, please visit us at http://www.streetdeck.com/forum for official support for Streetdeck.

                          Comment


                          • #14
                            ^^^^
                            Voltage on caps is the highest voltage a cap is rated on. Don't go over it.
                            Farads is the actual capacity.

                            Comment


                            • #15
                              Rather than screwing around with the LED idea, which I think is better to give up on now, find a diagram of the power locks.

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