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| messydeer | Jabiru Magneto Wiring | |||
| Craig Winkelmann | Re: p-lead signal conditioning or tach gen usage | |||
| Robert L. Nuckolls, III | Re: Re: p-lead signal conditioning or tach gen usage | |||
| Robert L. Nuckolls, III | Re: Re: p-lead signal conditioning or tach gen usage |
Subject: Re: Re: p-lead signal conditioning or tach gen usage From: Robert L. Nuckolls, III (nuckolls.bob@aeroelectric.com) Date: Thu Nov 05 - 3:20 PM At 03:38 PM 11/5/2009, you wrote: ><capav8r@gmail.com> > >Bob: > >Here is the circuit that is the current interface between the tach >gen and the EFIS tach input. It was originally designed to >interface a Hall sensor with a 10 V p-p input. The 50K resistor in >parallel with the zener was to provide a current path (so I am told) >should a p-lead be used instead of the Hall sensor. > >My thought was to put the circuit you have proposed in the location >as shown in the attached document (I could not scan to a .jpg and >the .bmp was way too big). Okay. I think your 'trash' is coming from artifacts on the wave-form that are a result of the combination of the two phases of a 3-phase generator. These seem to reside some millivolts away from ground . . . so your results are bound to improve if you move your comparator's decision-point as close to ground as possible. Try the simple transistor-zener circuit without the comparator. The transistor's "decision point" is in the .5 to .7 volt range as a function of Vbe characteristics of b-e junction. Bob . . . --------------------------------------- ( It's MATRONICS FUND RAISER MONTH! ) ( Do your part to keep this marvelous ) ( tool sharp and available to all our ) ( brothers in the OBAM aviation ) ( community. ) ---------------------------------------
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