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Re: resonance clarifications

> How would I check for linearity?  Do you mean constant amplitude for 
> a range of frequencies?  

You can check for linearity by just hooking up the generator directly to 
your scope (without your coil attached) and running through the 
frequencies. The scope should not load the generator to any significant 
degree (especially if you're using a 10x probe).  I once had an old 
(Heathkit?) signal generator that would vary the voltage by over 50% as 
I was ramping up and down in frequency.  Scoping your oscillator will 
also give you some indication of how well your equipment works...if the 
square waves show up with nice sharp corners on your scope up to the 
maximum 1MHz, you should be good to go.  If not, something is 
running out of frequency response.  Connecting your coil in the way you 
described should give you a voltage minimum (=current maximum) 
when you hit the resonant frequency.  BTW - what kind of scope and 
oscillator did you get?

[ Tektronix Oscilloscope, (don't know the model), and Hewlett Packard
  signal generator and frequency counter  -- Chip ]


I have also wondered about using a square wave generator to tune a 
coil.  A square wave has a lot of harmonics, so it's probably not 
surprising that you're getting a lot of different sine waves out as the 
different frequencies get attenuated and reinforced.  Does anyone else 
have any experience or thoughts about this?


Steven Roys (sroys-at-radiology.ab.umd.edu)