knock knock

[Tom Cloud]

>for those of you that requested the knock scematic and have not received
>it yet let me know and I will reship it. Remember computers are not a
>perfect science (MICROSOFT).
>	For those of you that did receive it let me know what you think of the
>simple circuit.
>
>Steve "Keep the Greasy side down" Parkman  
>

I got it .... opened it with MickeyStuff Word and it looks okay;
prints okay.

  - have you used this ??  (dumb question, I hope)

  - have you verified that it works ??

  - the reason I ask is that I'm led to understand that each
    engine configuration has a very **narrow** band of frequencies
    that represent knock -- and your .047 uF filter is certainly
    not "narrow"

  - this circuit seems to actually just measure "noise", not
    knock ????  .... the input bridge/filter combo is just what
    is called an "envelope" detector ... i.e. it yields a DC
    signal proportional to the peak excursion of the input
    signal and represents the outer "edge" of the signal

I have a long-range plan to take my knock sensor and a spectrum
analyzer and do some driving (trying to miss running over things
whilst I watch the spectrum analyzer -- it has no hard copy
output).  Note that RatShack used to make a hand-held spectrum
analyzer (or was that a sound level meter ... ???? don't remember
anymore  8^)

I guess, Steve, that my first reaction is to question the efficacy
of this circuit

Tom Cloud

       All generalizations are false (there are NO absolutes)