Generating nice Sine wave

[nerginer]

That is a great talking thanks alot to all of you. First of all this is not an inverter. The current can be around 200 mili amps. I did not need too much power. As I said the circuit will be powered by battery.
I think the circuit will have two parts. One is a sine generator this can be a microcontroller based or a wien bridge oscillator the second part will be an opamp base analog circuit to get -12v to +12v sine wave.

 

[goldsmith]

Dear dselec
Yes , i'm agree with you .
So , Dear nerginer
What is your power ?
Regards
Goldsmith

---------- Post added at 22:56 ---------- Previous post was at 22:52 ----------

And Dear LvW
Hi
As i told , he can use a potentiometer , in series with that resistor , ( about 20K ) . you're right ( it's loop gain is low) . i just wanted , to introduce him , a wien bridge oscillator , and those values are default of PSPICE . and are not correct.
Thank you
Best Regards
Goldsmith

 

[js]

That is a great talking thanks alot to all of you. First of all this is not an inverter. The current can be around 200 mili amps. I did not need too much power. As I said the circuit will be powered by battery.
I think the circuit will have two parts. One is a sine generator this can be a microcontroller based or a wien bridge oscillator the second part will be an opamp base analog circuit to get -12v to +12v sine wave.

So about 2W ?.... you need audio amplifier for example!

 

[nerginer]

Is there an opamp to get 2w-4w power or can you suggest me a component to do this

---------- Post added at 22:44 ---------- Previous post was at 22:40 ----------

can LM4871 be a solution ?

 

[goldsmith]

not opamp ! you can find LM12 with 80W power ! but it is not cheap way . try LM386 or TEA2025 .
Respect
Goldsmith

 

[nerginer]

what about the negative voltage? The components have gnd not -v

 

[goldsmith]

can you tell me that what do you mean by "what about the negative voltage? The components have gnd not -v"?
Respect
Goldsmith

 

[nerginer]

I think I need a professional help from an electronic engineer for a complete design. I mean in an opamp circuit I connect +12v gnd and -12v to their place. I can not find the pin to connect the -12v for the tea2025

 

[goldsmith]

it don't need -vcc . but it's out put is simultaneous , without problem and with high quality.

 

[nixiepixie]

I would say buy a couple of opamps they cost nothing and try it out they are very easy to use, like ne5532 orso.
If you need more current then a small opamp can deliver that is like your microcontroller, you have to make use of 4 mosfets with a couple of resistors as driving circuit...like a mosfet H bridge.
You can also use a larger audio amp ic but there datasheets are much more difficult to read I think and you are limited to the current the output capacitor can deliver.
Do not forget to put a capacitor in series with the output of the opamp you will not get a negative period at the output.
Like 47uf to 470uf , but do not use a opamp with a capacitor if a pulse at power up like a hifi amplifier is a big problem! but I think that will not be the case for you. Feed the opamp with 12 or a little more volts.

 

[goldsmith]

hello dear nixiepixie
the mosfet hbridge ? it need SPWM signal and it contains , triangle wave generator , dead time creator and .....
so for this power it will be very expensive . and as he mentioned , he need a cheap and high quality circuit .
Best Regards
Goldsmith

 

[keith1200rs]

This seems to be a long thread getting nowhere.

Nerginer, if you are happy with generating your sine wave from a micro then do it that way. If you want to do it with a Wien bridge then you need an amplitude stabilisation method (the light bulbs you have seen, although I prefer a JFET) otherwise you will end up with a square wave oscillator. This is a circuit with amplitude control (which works):

For the drive, I am not sure if you have a floating load or not i.e. does one end have to be connected to ground (0V)? If so then you need a +/- supply. If not then you can use a bridge type audio driver which will give you 24V peak to peak from a single 12V supply. By driving both ends of the load you effectively double the peak to peak drive.

So, you could use the TEA2025 and drive it in "bridge" mode as in figure 4 or 5 of the data sheet, depending on which version of the data sheet you are looking at. I don't think you will get 24V peak to peak with a 12V supply but the data sheet doesn't give output voltage swing.

Another option is the LM386-4 but you would still have to drive it in bridge mode to get your voltage swing - it cannot be powered from +/-12V. You would need two of them. There is an application in the datasheet for a Wienbridge oscillator but it would only give you maybe 12V peak to peak maximum depending on your supply voltage. The LM386 would be a bit messier to use than the TEA2025 as it doesn't like gains less than 10, although there are ways round that (see the data sheet).

Other options are to add a push-pull complementary emitter follower to a conventional opamp but that is not as straightforward as using off-the-shelf building blocks such as audio power amps.

Keith.

 

[goldsmith]

dear Keith
Hi
As i understood , he just want a single frequency , sine wave , so i don't think that AGC , is important here ( he can calibrate it with gain potentiometer , or simply with 2 diodes in feed back path (to break the feed backed voltage ) .
so i think it will be cheaper than using one fet and some auxiliary resistor and some capacitor . isn't it ?
Best Regards
Goldsmith

 

[LvW]

Goldsmith,

from the THD point of view a diode-based gain stabilization (better: limitation) is less effective as a good working AGC loop.
That's quite normal in electronics: You have to pay less effort with degraded performance.

---------- Post added at 14:33 ---------- Previous post was at 12:35 ----------

For the drive, I am not sure if you have a floating load or not i.e. does one end have to be connected to ground (0V)? If so then you need a +/- supply. If not then you can use a bridge type audio driver which will give you 24V peak to peak from a single 12V supply. By driving both ends of the load you effectively double the peak to peak drive.

Hi Keith,

just one short question: What is the purpose of C3? For my opinion, it is necessary for single supply operation only. Right?

 

[keith1200rs]

Hi Keith,

just one short question: What is the purpose of C3? For my opinion, it is necessary for single supply operation only. Right?

I wish I knew! I just did a quick search of my designs to see if any had the word "Wien" in them. It simulated OK so I posted it. I don't think I ever built it - it was part of a comparison on techniques to demonstrate to someone. It simulates OK without it and it seems to be very close to the circuit on page 297 of "The Art of Electronics" by Horowitz & Hill, so that is where I got it from.

Out of interest, this circuit gives pretty low distortion for people with JFET phobia (better than simply using diodes in the feedback):

edit: one note is that it has poor amplitude control with temperature

Keith.

 

[dselec]

To negineer
"I need professional help from an electronic engineer"
No u dont.
all u need is to get down and get your " hands dirty " and start " breaking your head "
google "tea2025b pdf " and start reading every ting is there like food on your plate .
Then every body will help u when u show a little effort from your side .
Then ill explain why u need 24 v and how to attach your ps to circuit .
I am sure after u read u will know it your self.
good luck

---------- Post added at 16:07 ---------- Previous post was at 16:00 ----------

As for goldsmith.
Do u think if he uses tea2025b in stero mode and the 2 inputs 180 in phase he will get a +/- 12 v or 24vac pp swing , between the two outputs ?

 

[LvW]

Then every body will help u when u show a little effort from your side .

This is to be emphasized!

 

[goldsmith]

As for goldsmith.
Do u think if he uses tea2025b in stero mode and the 2 inputs 180 in phase he will get a +/- 12 v or 24vac pp swing , between the two outputs ?


Hello Dear dselec
Yes , you're completely right . it's out put will be about 7 volt at best situation !
But as he told , he just want 2 wat , but this IC , can give you the powers up to 5W !
and i think about this , but i don't know that is it possible or no : use a butterworth filter after that , with critical value of zeta , thus the out put voltage can increase , as high as possible ( after that IC ).
So what do you thing about this ?
Regards
Goldsmith