[sdiy] LC osc for AF

[Toby Paddock]

Thanks John and everyone for the LC tips.
They helped a lot to get me started.
It's funny how much you can forget if you
don't use something for a few years.
Like 30  : )
Comments inline.
Later,
Toby Paddock

John L Marshall wrote:
> Toby,
>
> I can't tell if you got the answer that you are looking for. Here are
some
> ideas:
>
> 1. Hartley oscillator; tapped coil, maybe 10% to 20% and capacitor in
> parallel. In a transistor circuit, top of coil to base through
blocking
> capacitor, tap to  emitter, bottom to ground.
>
> 2. Colpitts oscillator, tapped capacitor, and inductor in parallel.
similar
> connection.
Colpitts sounds like a good place to start.

>
> 3.Tickler feedback with a second small winding close coupled to the
tank.
> The tank may be in the base circuit or the collector circuit.
Hmmm... ocillators with intercoupled ticklers?

>
> I just checked "The ARRL Handbook for Radio Amateurs" there are FET
circuits
> for Colpitts and Hartley.
Yeah, that's the book I'm most looking for. Mine's '74 or thereabouts.
Just found Shrader "Electronic Communication" 1975 which looks
promesing.

>
> BTW "The Handbook", while intended for hams, is loaded with really
good
> information on topics that appear on this list such as, grounding,
EMI,
> testing, general theory, and so on. Published yearly. Teory doesn't
change
> get an old one cheap.
>
> Another thought. Use an opamp and put the series LC in the positive
feedback
> path and something non-linear (lamp or diodes)  in the negative
feedback
> path. The L and C will oscillate just fine. You just need to give it a
small
> kick to keep it going. Give it too big of a kick and and the sinewave
clips.
Series LC instead of a tank? Interesting.

>
>
> Take care,
> John
> www.sound-photo.com
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