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Design >> RF Design >> Design of a Hartley Oscillator
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Message started by tripod2000 on Nov 2^nd, 2006, 2:46am

Title: Design of a Hartley Oscillator
Post by tripod2000 on Nov 2^nd, 2006, 2:46am

Hey all,

http://www.electronics-tutorials.com/oscillators/oscillator-basics.htm shows a Hartley oscillator and a Colpitts circuit. There is a formula for finding a frequency of a Colpitts oscillator, but not a Hartley oscillator. I believe I need a Hartley oscillator for my design with a frequency of about 100kHz or about 1MHz. Could someone please suggest a formula to work out what values of componants I would need.

(I will have a variable capacitance.)

Thank You ;)

Title: Re: Design of a Hartley Oscillator
Post by loose-electron on Nov 2^nd, 2006, 7:52am

That web site uses small signal schematics with a large signal transistor in the middle of it. Also, the Hartley Colpitts oscillators don't get used a heck of a lot anymore. They tend to exist in one transistor designs from prior to 1965 or so.

Care to tell us a bit more about what you are trying to do and perhaps we can be of help?

thanks
Jerry

Title: Re: Design of a Hartley Oscillator
Post by tripod2000 on Nov 2^nd, 2006, 9:07am

I'm working on a control system like a Theremin. I want the oscillator frequency to change with a changing capacitance caused by a hand moving near an aerial. I figured on the Hartley because of the changing capacitance, the simplicity (cost being a factor in the design) and the feedback ration being constant seemed like a good idea.

Thank You.