triangular to sine wave

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kahafeez

Joined Dec 2, 2008
150
hi people i constructed a 741 op amp oscillator. it is giving an output bt its a triangular wave.... but i want a pure sine wave... how do i get a sine wave... the freq is around 40KHz.... i used a wein bridge config... like the one shown in the figure..... either tell me how to get a sine from the osc or tell me how to shape a triangular to a sine wave.....
 

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Wendy

Joined Mar 24, 2008
23,415
One of your capacitors is shorted, this would contribute. You will probably need a better op amp, but fix that cap first.
 

Ron H

Joined Apr 14, 2005
7,063
hi people i constructed a 741 op amp oscillator. it is giving an output bt its a triangular wave.... but i want a pure sine wave... how do i get a sine wave... the freq is around 40KHz.... i used a wein bridge config... like the one shown in the figure..... either tell me how to get a sine from the osc or tell me how to shape a triangular to a sine wave.....
If you do it right, that is a Wien Bridge oscillator. It generates sine waves. Google "Wien Bridge" for lots of information.
 

Audioguru

Joined Dec 20, 2007
11,248
The lousy old 741 opamp (it is 40 years old this year) is so slow that it turns all signals above only 9khz into a triangle-wave. A TL071 audio opamp and many other opamps work up to 100kHz. An OP134 audio opamp work up to 250kHz.
 

Ron H

Joined Apr 14, 2005
7,063
The lousy old 741 opamp (it is 40 years old this year) is so slow that it turns all signals above only 9khz into a triangle-wave. A TL071 audio opamp and many other opamps work up to 100kHz. An OP134 audio opamp work up to 250kHz.
AG, you should add parenthetically: "This is a recording.";)
 

SgtWookie

Joined Jul 17, 2007
22,230
When you were learning to drive, did you start off in a Lamborghini Countach?

Probably not...

I started off driving in a '63 Fiat 1100D (looked like a scaled-down Checker cab, engine was a 1088CC 4-cylinder) that had tires thin as baloney skins in the rear. It was so underpowered, you'd have to drive it off a cliff with a tailwind to get it up to 70mph.

It sure made me appreciate my '65 Mustang GT convertible a lot more. ;)
 

leftyretro

Joined Nov 25, 2008
395
When you were learning to drive, did you start off in a Lamborghini Countach?

Probably not...

I started off driving in a '63 Fiat 1100D (looked like a scaled-down Checker cab, engine was a 1088CC 4-cylinder) that had tires thin as baloney skins in the rear. It was so underpowered, you'd have to drive it off a cliff with a tailwind to get it up to 70mph.

It sure made me appreciate my '65 Mustang GT convertible a lot more. ;)
Hey! I had a brand new '66 Mustang GT fastback, yellow with black interior. I loved that car, but sold it when married and the kids started popping out.

PS: I found an interesting backdoor circuit in that car. Without a key in the ignition if you turned on the safety blinker, put foot on brake the radio would pulsate on and off with the blinker timing :D
Lefty
 

Ron H

Joined Apr 14, 2005
7,063
When you were learning to drive, did you start off in a Lamborghini Countach?

Probably not...

I started off driving in a '63 Fiat 1100D (looked like a scaled-down Checker cab, engine was a 1088CC 4-cylinder) that had tires thin as baloney skins in the rear. It was so underpowered, you'd have to drive it off a cliff with a tailwind to get it up to 70mph.

It sure made me appreciate my '65 Mustang GT convertible a lot more. ;)
So what's the lesson here? Start out with a crappy op amp, so you will appreciate the better ones when you can afford them?:D
 

Audioguru

Joined Dec 20, 2007
11,248
I think that teachers don't know that a lousy old 741 opamp has poor performance and that there are much better opamps available at the almost the same price. Besides, the text books are old.

Today at Digikey, an LM741 single opamp costs $.49US each, A much better single TL071 costs $.53US each and a much better dual TL072 costs $.50US each.
 

Wendy

Joined Mar 24, 2008
23,415
Don't worry, students are killing them one at a time, then they get the good ones.

I remember seeing the top pop off one in one of my classes so long ago.
 
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