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  • delay circuit

    Anyone know where I can purchase a delay circuit, or a simple one I could build?

    Not absolutely sure that delay circuit is the right name. But basically I need something that'll cause my amp to delay about 5 seconds before powering on, to prevent the bootup 'pop' from the computer from being amplified.

    The amp already has its own soft-on circuitry, but it's not long enough. At the moment I work around it by simply turning on my amp after the computer (from switches in the dash), but it'd be nice to have it non-pop if I leave both switches on and start the vehicle.
    Player: Celeron II 633MHz, 256MB RAM, 20GB IBM 9mm 2.5" Laptop HD (180G/2ms), onboard ethernet/sound/video/tvout, 10"11"x3" case, MPBS1 70W DC-DC PS w/auto-shutdown controller, in-dash lighted switches, 7" NTSC TFT widescreen in-dash LCD, touchscreen, rear-window brake light installed Garmin GPS35 GPS, credit card sized IR remote w/IRMan, mini-wireless keyboard/mouse (sits under seat), PowerMate black knob, MP3s and GPS Navigation (Winamp, CoPilot, SA8.0).
    Car: 1993 Nissan Maxima, Black Emerald

  • #2
    I use the DTR line from a serial port for remote amp turn-on. The DTR line is low at boot, then I set it high in software (not sure what's the easiest way to do this in Windows, though). If you do this, use a small fuse on the line just in case...
    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...

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    • #3
      Can you please describe this method with more details please ? (COM DTR...)
      ----
      http://www.CarTFT.com

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      • #4
        Yes, PLEASE... this would be VERY nice.

        (I'm getting quite sick of forgetting to shut my amps off before I boot... sounds like someone fires a gun in the back seat when the computer boots )
        Public PGP key available on http://keyserver.pgp.com/pks/lookup?...@MyRealBox.com

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        • #5
          Hmmm, let's see. As far as hardware is concerned, the DTR line is pin 4 on the DB-9 connector (pin 20 on DB-25). So you just run a wire from this pin to the remote-on terminal of the amp, but put a small fuse (250mA or so) on the computer side of the wire, just to be safe -- otherwise a short could blow your serial port.

          The serial port will provide about +12V on the pin when some program opens the serial port and sets the DTR line "high". This will tell your amp to turn itself on. When the program sets the DTR line "low", the pin drops to -12V and turns the amp off (you might want to add a diode to the wire to make -12V appear as 0V. I did not do this, and it works fine anyway.)

          Now, as far as software is concerned, fortunately I really have no idea how you can manipulate DTR under Windows (see my sig...) Check with a multimeter: DTR might be set high at boot time already. Can anyone else here comment on this?

          Good luck.
          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
            Setting that to high could easily be done with a C++ .exe that you could put in your autoexec!

            I could write it up for you real quick-like on monday, but I'm in Houston right now on my laptop, and don't have a compiler with me
            www.arbybean.com

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            • #7
              How about connecting your amp's remote turn-on to a 12V hard drive connector coming out of the power supply?

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              • #8
                I'm thinking of make simple delay to amp's signal-pin or whatewer(low A start like relay)

                like this
                Code:
                  
                                     Resistor
                
                computer ps 12V >--|===|----+--< amp sign.
                                        |
                                        = Capasitor
                                        |
                                        +gnd
                
                
                When I turn comp on The resistor will slowly rise the C voltage to 12 V and amp will go on!
                
                But how about disabling the shutdown *bumb*???
                WINAMPCAR
                Project almost ready

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                • #9
                  The whole point of using DTR is to be able to turn the amp on _AFTER_ the PC is on (delay-on), and to turn it off _BEFORE_ the PC is off (pre-off). Using a +12V line from the power supply doesn't help at all, you'll still get the thumps. And while you can do a simple delay-on circuit like embedded suggested, there's no way you can do anything similar for pre-off -- a simple circuit, not being able to see the future, can't tell when your PC is about to turn itself off. But software can.
                  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


                  • #10
                    I'm pretty sure I can handle writing a serial port app to handle the DTR. I might even be able to get it to work for the 2000 guys. I'll have to try the wiring trick when I get home, and whip out my compiler for the software.

                    I'll report back if I have any success, and share the software if it's worth having.

                    -M
                    Public PGP key available on http://keyserver.pgp.com/pks/lookup?...@MyRealBox.com

                    Comment


                    • #11
                      Interesting idea embedded.

                      A simple circuit to me is more what I need rather than another thing to plug into the computer.

                      I personally don't have shutdown pop problems with my system -- I don't shutdown. Anytime the computer goes off, the amp goes off at the same time. I just need to the delay circuit for when they start.

                      Any idea what kind of resistors, size capacitors, etc would be necessary?
                      Player: Celeron II 633MHz, 256MB RAM, 20GB IBM 9mm 2.5" Laptop HD (180G/2ms), onboard ethernet/sound/video/tvout, 10"11"x3" case, MPBS1 70W DC-DC PS w/auto-shutdown controller, in-dash lighted switches, 7" NTSC TFT widescreen in-dash LCD, touchscreen, rear-window brake light installed Garmin GPS35 GPS, credit card sized IR remote w/IRMan, mini-wireless keyboard/mouse (sits under seat), PowerMate black knob, MP3s and GPS Navigation (Winamp, CoPilot, SA8.0).
                      Car: 1993 Nissan Maxima, Black Emerald

                      Comment


                      • #12
                        I can't remember the way to calculate the R % C

                        No, its here
                        T=R*C
                        I would remember that C has to be in microfarads (The uF)
                        WINAMPCAR
                        Project almost ready

                        Comment


                        • #13
                          Originally posted by embedded:
                          <STRONG>I can't remember the way to calculate the R % C

                          No, its here
                          T=R*C
                          I would remember that C has to be in microfarads (The uF)</STRONG>
                          The units of C is farads, not microfarads for calculating the time constant. if you have a 10 uf cap and a 10 k ohm resistor, it would be 0.1 seconds.

                          Would you guys be intersted in any circuit boards? I can get boards fabricated, a custom 3 by 1 inch board that could hold a relay, circuity and connectors would cost about 8 bucks a board. Not bad if you don't want to use wires that can break on the radio shack boards.. If enough people are intested in a custom delay circuit, I could have some built..

                          Jeff_
                          MPEGBOX - Plexiglass Computer
                          www.mpegbox.com

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                          • #14
                            Whatever became of this delay circuit? I would be willing to pay someone to build a simple circuit that would turn my amps on a few seconds after I press the power button on my computer, and a few seconds before my computer powers off it would turn my amps off. I have a bad case of the pops!!!

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                            • #15
                              Hmm

                              How would it know that you are turning your computer off. Sees ya coming for the button? :-)
                              MPEGBOX - Plexiglass Computer
                              www.mpegbox.com

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