The Peltz oscillator as a Code Practice Oscillator

Mentioned previously:

https://wb9kzy.blogspot.com/2024/11/the-peltz-oscillator-circuit.html

I tried changing the keying so that a normal key closure to ground could be used, the PNP transistors (I used two 2n4403 PNP transistors but the 2n3906 or others should work as well) and the positive supply voltage help.  A 10 k ohm pot was added (R4) and adjusted until oscillation stops (about 3.8 k ohms).

The oscillation cutoff happened at a supply current of about .435 mA.  Then when the key is closed the supply current increases slightly to .45 mA and oscillation begins.  I first saw this keying technique mentioned in a Hint and Kink by Denton Bramwell, K7OWJ:

https://wb9kzy.blogspot.com/2022/02/wien-bridge-audio-oscillator-keying_27.html

The result is a little thumpy, more shaping is probably required which would complicate things.  But the stumbling block is really that inductor, high value audio inductors aren't as easy to come by anymore.  Here I used the primary center tap winding of an audio output transformer.  The cap value could be changed to for a different sidetone frequency.

It was fun to try but not sure it's of much practical use.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm