REFLECTOR: Magneto P-lead pickup circuit

[Jim Agnew]

I can't help you on a specific mag, we used mt Bendix mags and Sam DaSilva's
Slicks for the comparison.

Jim
 
--- Brian Michalk <michalk at awpi.com> wrote:
> It's a Slick M-6088 magneto.
> 
>  Brian Michalk  <http://www.michalk.com>
> Life is what you make of it ... never wish you had done something.
> Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
> musician, home-brewer, entrepreneur and barely single
> 
> 
> > -----Original Message-----
> > From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> > Behalf Of Jim Agnew
> > Sent: Sunday, March 13, 2005 1:09 PM
> > To: Velocity Aircraft Owners and Builders list
> > Subject: Re: REFLECTOR: Magneto P-lead pickup circuit
> >
> >
> > Brian,
> >
> > First it depends on what mag you are using, Slick or Bendix.  I have High
> > Altitude (read high output) Bendix Mags and their P-lead wave
> > form drove my
> > electronic tac nuts requiring a change in the filtering circuit.
> >
> > The wave form is basically a very sharp peaked sine wave of decreasing
> > amplitude (ringing) and some fixed number of cycles depending on
> > the mag.  If I
> > remember the Slicks had about 5 cycles and the Bendix 7 or 8.  It
> > was a long
> > time ago and a lot of time with an oscilloscope.
> >
> > Jim
> > --- Brian Michalk <michalk at awpi.com> wrote:
> > > I am working on my backup EFI circuit, and am considering a
> > pickup off the
> > > magneto P-lead as one of the RPM inputs.
> > >
> > > I machined a collar that mounts on the crankshaft that feeds the crank
> > > position signal to the Autronic, an off the shelf engine computer.  The
> > > Autronic provides spark and injection.  My backup spark is a
> > magneto.  My
> > > backup fuel injection is a system I designed myself.  It takes
> > RPM and MAP
> > > to determine commanded fuel flow, and then a fuel flow input to make it
> > > closed loop.  I will be taking one signal off the tach drive, and wanted
> > > another signal.  I can get it from the above mentioned collar,
> > or from the
> > > magneto.
> > >
> > > My thinking is that an alternator belt could fail, thrashing
> > about and cause
> > > my RPM sensor to fail.  Does anyone have a schematic on picking
> > up a tach
> > > signal off the magneto?  I have no idea what that waveform looks like.
> > >
> > >  Brian Michalk  <http://www.michalk.com>
> > > Life is what you make of it ... never wish you had done something.
> > > Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
> > > musician, home-brewer, entrepreneur and barely single
> > >
> > >
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> > >
> >
> > James F. Agnew
> > Jim_Agnew_2 at Yahoo.Com
> > Tampa, FL
> > Velocity 173 Elite Aircraft Completed & Flying
> > _______________________________________________
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> 
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James F. Agnew
Jim_Agnew_2 at Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed & Flying