how does a knock sensor work?

[David Gravereaux]

Mark Agnello <m_agnello at yahoo.com> wrote:

>David,
>
>> 
>> Just say it has an extremely high output impedance. 
>> That rings my bell, at
>> least :)
>> 
>> That can be solved with a good FET buffer as the
>> input stage with a really high
>> input impedance around 40 MegOhms.  I reengineered
>> the front-end to an AKG 451
>> condenser mic once.  The schematic looked something
>> like this:
>
>I think many modern automotive knock sensors are
>actually designed like this.  They have built in
>buffers that hopefully eliminate the sensitivity to
>cable condition.
>
>Mark

Oh..  At the sensor end would work great.  Good idea.  That's just a third wire.
Built into the connector maybe.  Design work is fun.
--
David Gravereaux <davygrvy at pobox.com>

$ make war
make: *** No rule to make target `war'.  Stop.  Try `love' instead.
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