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Re: [RE: [SeattleRobotics] Coils and Sparks]

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  • usa.net
    This is the thread that sparked my interest in starting to write to the mailing list, pardon the pun. :) A computer power supply is a much different circuit
    Message 1 of 1 , Mar 2, 2003
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      This is the thread that "sparked" my interest in starting to write to the
      mailing list, pardon the pun. :)

      A computer power supply is a much different circuit than a battery. My first
      guess was that there may be an inductor inside the power supply that's getting
      into the act, but capacitors would also store energy. There's a nice tutorial
      on DC-DC power supplies on Maxim's web site, app note 710,
      http://www.maxim-ic.com/appnotes.cfm/appnote_number/710/ln/en.

      I'd be a bit concerned about stressing a computer power supply with surge
      currents, since they are designed for a less-demanding load. I also recall
      that switching power supplies typically have minimum load requirements, so the
      12V output might rise above 12V when it has minimal load.

      "John B" <jbpublic@...> wrote:
      > The most obvious reason would be a difference in the wiring resistance
      > between the two setups but I assumed you ruled that out. My guess is that
      > it was due to the power supply's capacitors being able to provide more
      > instantaneous current.
      >
      > > -----Original Message-----
      > > From: Bob Dyer [mailto:bd@...]
      > > Sent: Saturday, March 01, 2003 8:26 PM
      > > To: SeattleRobotics@yahoogroups.com
      > > Subject: RE: [SeattleRobotics] Coils and Sparks
      > >
      > >
      > > The battery shouldn't be any different than the power supply unless it
      was
      > > severely discharged. How did you get the "10x" number? Could this
      > > have been an
      > > "illusion"? Perhaps it was brighter out where you tested with the
      > > battery, and
      > > darker inside with the power supply. Maybe it only looked "10x greater".
      > >
      > > -----Original Message-----
      > >
      > > At 01:32 AM 3/1/2003 +0000, busterbot <BusterBot@...> wrote:
      > > >
      > > >I have ignition coil from a car and transistor module that fires it,
      > > >I have 2 spark plugs connected to it and when I trigger the module,
      > > >they do indeed spark. I have the power lines connected to the car
      > > >battery 12v. Car wasturned off so power running straight from
      > > >battery no help from alternator.
      > > >
      > > >I took the setup into my house, and hooked the power lines to a
      > > >computer powersupply, the 12v 9a (yellow) wire, ground to ground and
      > > >to the sparkplug threads. The trigger line I used the 5v (red) wire
      > > >from the computer power supply. When i triggered it, the spark was
      > > >about 10x greater then the car battery and I cant figure out why? I
      > > >know the car battery defintly can supply way more then 9amps for a
      > > >decent amount of time,
      > > >
      > > >So why was the spark so much more intense with the computer
      > > >powersupply then the car battery?
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      > >
      > > Visit the SRS Website at http://www.seattlerobotics.org
      > >
      > > To unsubscribe from this group, send an email to:
      > > SeattleRobotics-unsubscribe@yahoogroups.com
      > >
      > >
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