I had been trying to build a variable wien bridge oscillator . The schematic is shown below - I wanted to change the frequency by using a pot . But it starts to distort after 12 Khz. Also when i am reducing both the capacitors to 1 nF I find the waveform to be triangular more than sinusoidal. Also if I want to drive 0.5 w 8 ohm ospeaker should i use an op amp or an lm386 ? Also how do i change the frequency with one control pin?
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You need a faster opamp than a 741 for high frequency use. The Wien bridge has two frequency determining networks and so normally you would use a dual gang pot.
Controlling an oscillator with a single input usually implies a 'voltage controlled oscillator' whose basic waveshape is often triangular. This is then shaped via a diode network to approximate a sine wave.
http://www.ti.com/sc/docs/apps/msp/journal/aug2000/aug_07.pdf
Controlling an oscillator with a single input usually implies a 'voltage controlled oscillator' whose basic waveshape is often triangular. This is then shaped via a diode network to approximate a sine wave.
http://www.ti.com/sc/docs/apps/msp/journal/aug2000/aug_07.pdf
I think you need something faster than a 741.
That is a classic sign of slew rate limiting... the opamp output can't keep up.Also when i am reducing both the capacitors to 1 nF I find the waveform to be triangular more than sinusoidal.
Of course there are oscillators with 1 adjustment element, I designed one also, but not wien bridge. Not this simple or not low distortion.
I had built the oscillator and now I want to drive it using a speaker . So i Had used an emitter follower . BUt somehow the speaker is giving a very reduced voice output. How do i increase the power more. Also can you give the schematic of your oscillator
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I had built the oscillator and now I want to drive it using a speaker . So i Had used an emitter follower . BUt somehow the speaker is giving a very reduced voice output. How do i increase the power more. Also can you give the schematic of your oscillator
Attached a simple square+triangle+sine generator. The sine is very rough, THD is about 2...5%.
For higher power you can use any power amp IC, or if you like emitter follower, then it should be complementary, with a little higher quiescent current.
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Documents of interest:
http://www.sdiy.org/colbecklabs/spec_sheets/AN-263.pdf
ftp://ztchs.p.lodz.pl/PRP/PRP_2008_2009/LB-16.pdf
And in the context of speaker driver applications, this one too:
http://www.diyaudio.com/forums/chip-amps/254384-automatic-resonance-frequency-finder.html
http://www.sdiy.org/colbecklabs/spec_sheets/AN-263.pdf
ftp://ztchs.p.lodz.pl/PRP/PRP_2008_2009/LB-16.pdf
And in the context of speaker driver applications, this one too:
http://www.diyaudio.com/forums/chip-amps/254384-automatic-resonance-frequency-finder.html
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