This one from the bottom of the 1st page:

http://www.analog.com/static/imported-files/application_notes/46855865AB111.pdf

 

RogerTango says he wants to make the frequency variable. A Wien bridge (or any other type of RC sine wave oscillator that I know of) requires that at least two component values be changed simultaneously in order to vary the frequency. This generally means ganged pots, because ganged variable capacitors (if you can even get them) are generally too low in value to make an oscillator in the audio frequency range. Ganged pots are available, but they don't necessarily have good tracking. Tracking errors stress the oscillator's AGC circuit, causing more harmonic distortion. All this is probably not a big deal for a code practice oscillator. I just think a function generator IC is simpler for this application.

EDIT: Ganged pots may not be practical for tuning in the single-supply circuit in the Analog Devices app note.

 

I just think a function generator IC is simpler for this application.

I think your right Ron, Im looking for the simpliest circuit for the XR2206 right now.

Thanks,
Andrew

 

Here's a 2206 kit for $35. The schematic is also shown. Its pretty simple as it is but could be made even simpler if you delete the parts you won't use like 3/4 of the range caps.

http://electronics-diy.com/Function_Generator_XR2206.php

 

Thanks Joe, that schematic is just what I was looking for! Im not about to buy the kit... but the chip is no problem. I hope to etch my own PCB to include the keyer and relay circuits (just need a new laser jet is all...).

Big help, thanks much!
Andrew

Edit:
Having a bit of trouble figuring out where the resistors go... and do I really need *audio* capacitors?