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Design >> Analog Design >> controlling the frequency of oscialtor
https://designers-guide.org/forum/YaBB.pl?num=1367563688

Message started by neuro11 on May 2^nd, 2013, 11:48pm

Title: controlling the frequency of oscialtor
Post by neuro11 on May 2^nd, 2013, 11:48pm

Hi, is there a oscilator type, the frequency of which can be controlled using one component(capacitor). I mean unlike wien bridge oscilator where RC network determines the condition of oscilation and frequency of oscilaion, i want a oscilator of which frequency can be controlled by a capacitor indepoendent of conditions for oscilations.

Please help!!!

Thnx

Title: Re: controlling the frequency of oscialtor
Post by raja.cedt on May 3^rd, 2013, 12:18am

read about VCO....

Title: Re: controlling the frequency of oscialtor
Post by neuro11 on May 3^rd, 2013, 4:07am

raja.cedt wrote on May 3^rd, 2013, 12:18am:

read about VCO....

Hi, thanks for your reply. I will check VCO.
Could you please look at the schematic i attached. I have designed it based on a paper where the author explained the ic model, compnent value every thing and claimed the oscilation can be controlled through C2 only (from 10p to 1n) and oscilation condition depend on C1/C4= R2/R4. But somehow i cant make it work.
Please have a look if i am missing something.
Thanks

Title: Re: controlling the frequency of oscialtor
Post by raja.cedt on May 3^rd, 2013, 5:12am

hello,
what kind of oscillator this? but there is some problem at opamp input pin number 3, there is no bias so it will not work.

Title: Re: controlling the frequency of oscialtor
Post by neuro11 on May 3^rd, 2013, 7:55am

raja.cedt wrote on May 3^rd, 2013, 5:12am:

hello,
what kind of oscillator this? but there is some problem at opamp input pin number 3, there is no bias so it will not work.

Sorry i have corrected it.

Title: Re: controlling the frequency of oscialtor
Post by raja.cedt on May 3^rd, 2013, 8:31am

Hello,
Please have a look on wien bridge osc in google, you should have an -ve feedback around the op amp through some potential divider....

Thanks,
Raj.