All About Circuits Forum Variable frequency sine wave
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 The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

#1
09-21-2009, 01:49 AM
 gagan New Member Join Date: Sep 2009 Posts: 2
Variable frequency sine wave

hey guys. I want to build a variable frequency sine wave generator with a constant amplitude. any suggestions??

Thanks,
G
#2
09-21-2009, 01:54 AM
 Audioguru Banned Join Date: Dec 2007 Location: Ontario, Canada Posts: 9,411

A Wien Bridge oscillator using a light bulb or a Jfet for amplitude stabilization works well.
Mine goes from 10Hz to 100kHz.
#3
09-21-2009, 02:30 AM
 gagan New Member Join Date: Sep 2009 Posts: 2

hey thanks for the quick reply

I'm considering the following circuit
http://www.national.com/ms/LB/LB-16.pdf
Figure 1 Easily tuned sine wave oscillator

Can any one help me by explaining what exactly how sine wave is being genrated in the circuit.

Audioguru:- I did consider wien bridge option but can't figure out how to control the amplitude using jfet exactly. If you could explain a bit more on that part, then it will be great.

Thanks
#4
09-21-2009, 10:03 PM
 Bill_Marsden Super Moderator Join Date: Mar 2008 Location: Dallas, TX (GMT-5 w/ DST) Posts: 19,022 Blog Entries: 5

How pure does this sine wave have to be? If the answer is not extremely, then you can use other methods.

To answer your question the Zeners clip the wave form, leaving what is effectively an active filter to clean up the harmonics.
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 Tags frequency, sine, variable, wave

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