Today's Message Index:
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1. 09:01 AM - Re: tachometer (D L Josephson)
2. 12:34 PM - Re: Re: tachometer (Ernest Christley)
Message 1
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On 10/15/15 11:56 PM, CorvairEngines-List Digest Server wrote:
> Time: 06:19:00 AM PST US
> From: Ernest Christley <echristley@att.net>
> Subject: Re: CorvairEngines-List: Re: tachometer
>
> There are tachs that install in series with the coil.=C2- One of those wo
> uld be a very bad idea, and would concur with what you say.
> However, your statement concerning the ones that sense the current bounce o
> n the negative electrode does not concur with basic electronics.=C2- Unle
> ss a bad tach was somehow able to burn the short wire going from the coils
> negative terminal to the firewall, there is nothing it could do to affect t
> he coils operation.
It doesn't burn the wire, it shorts it to ground, bypassing the points.
What's been seen is that a bypass capacitor fails, probably due to
insufficient voltage rating or poor quality, and shorts the negative
lead to ground, taking the points out of the circuit. If you must use a
tach connected to the ignition primary, be sure you have two ignition
circuits and connect the coil to only one of them.
Message 2
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Aah!=C2- Gotcha!=C2- Thank you.
On Friday, October 16, 2015 12:02 PM, D L Josephson <dlj04@josephson.c
om> wrote:
com>
On 10/15/15 11:56 PM, CorvairEngines-List Digest Server wrote:
> Time: 06:19:00 AM PST US
> From: Ernest Christley <echristley@att.net>
> Subject: Re: CorvairEngines-List: Re: tachometer
>
> There are tachs that install in series with the coil.=C2- One of those
wo
> uld be a very bad idea, and would concur with what you say.
> However, your statement concerning the ones that sense the current bounce
o
> n the negative electrode does not concur with basic electronics.=C2- Un
le
> ss a bad tach was somehow able to burn the short wire going from the coil
s
> negative terminal to the firewall, there is nothing it could do to affect
t
> he coils operation.
It doesn't burn the wire, it shorts it to ground, bypassing the points.
What's been seen is that a bypass capacitor fails, probably due to
insufficient voltage rating or poor quality, and shorts the negative
lead to ground, taking the points out of the circuit. If you must use a
tach connected to the ignition primary, be sure you have two ignition
circuits and connect the coil to only one of them.
um -
S -
-
=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.
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