A bit OT - pickup analyzer

[Phorhas]

Hello, I wanna build a pickup analyzer. so... what's in there?

[Paul Perry (Frostwave)]

Tell me what it is, & then I'll have a guess!

[Penguin]

Tell me what it is, & then I'll have a guess!

haaaaaaaaaaaaaa 

[Fret Wire]

http://www.buildyourguitar.com/resources/lemme/index.htm

[Paul Perry (Frostwave)]

FretWire, that's the most interesting link I've seen for a long time! Thanks for that!

OK, I don't think I'm going to build a pickup analyzer... but if you were, it looks like you need a sine source where the amplitude is inversely proportional to frequency, plus an AC voltmeter & freq meter...... oh and the current driver for the signal coupling coil......

The cheap alternative, is to just make the driving coil, and do the maths by hand.
If you plot (guitar out voltage)/(driving coil voltage X frequency) against frequency, that might be the curve you want.

I think the matter of the driving coil was glossed over a bit. I can imagine (I could be wrong) that the coupling is more frequency dependant than one would wish. Plus maybe the presence of the strings will interfere?? Maybe this dosn't matter in practice.

As for a constant curent driver for the input coil, the output of an OTA (LM13700) is constant current, but whether there is enough current I don't know.. almost certainly not. Why does it need constant current? Maybe that is to prevent characteristics of the drive coil from interfering with the measurements. Interesting!