> Well, blast it, I just broke a string playing with it...  Obviously
> there's a better way to handle picking up the base frequency of the
> string...  anyone got a bright idea that doesn't involve op amps and a
> hundred components?

Your existing design is high pass in characteristic. The component values
give about a 1 kHz knee BUT the transistor input impedance is uncertain with
no emitter resistor and bypass and is probably rather low so true high pass
point is probably even higher. Try a MUCH larger input capacitor for
starters (say 10 to 100 uF).

A low pass filter with reasonable cutoff and Q MAY help.
You can achieve low pass filters with two poles per stage using a single
transistor as an emitter follower per stage. Component count is 3 Rs and 2
Cs per stage (2 x RC plus an R for emitter resistor). You could get two pole
slow pass by adding a few Rs and Cs to your exiting input stage and 4 poles
with another transistor.

I could provide component values for say 2 and 4 poles of low pass if you
are interested.



            Russell McMahon

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