Sine and?

[wizard]

Hi Wizard,



I simply connected two voltage sources with different
frequencies and amplitudes in series. Sorry no magic.
You don't need a modulator to achieve this result.
It's so simple I'm having difficulties to explain it.
I think you need a knock on your head.

on1aag.

I meant which SOFTWARE did you use to crate that signal?

 

[on1aag]

Hi Wizard,

Go to the website of Linear Technology and download
LTspice switchercad III, it's a free simulator, a lot
of our members use it.

Linear Technology - Linear Home Page

I noticed that it's LTspice IV now ?

on1aag.

 

[transistor495]

Hi Wizard,

Go to the website of Linear Technology and download
LTspice switchercad III, it's a free simulator, a lot
of our members use it.

Linear Technology - Linear Home Page

I noticed that it's LTspice IV now ?

on1aag.

Hi Wizard,
Don't believe it. on1 has created that particular type of signal by this time using some circuits and started broadcasting

 

[audioguru]

I noticed that it's LTspice IV now ?

I downloaded it now and tried it with an old circuit made with SwCAD III.
It looks the same but is called LTspice IV now.
I'll have to read all about it.

 

[wizard]

Hi Wizard,
Don't believe it. on1 has created that particular type of signal by this time using some circuits and started broadcasting

lol
Why don't you guys go and use 'PSpice'.
Oh, I think i know the reason,'$$$$$$$$$$$$$$$$'

Anyway please someone takes a look at my MAIN question!!
Here it is:

Good idea but let me say what my friend desires to do.
He wants to play a sine signal by a tweeter at say 12kHZ(audible) and carry a HIGH frequency signal on it(say 25kHz), If you know what I mean.
He wants to have a simple audible sound signal and an ultrasound signal at the output of the tweeter simultaneity. So you will hear the 12kHz signal by your own ears and the ultrasound signal by a RECEIVER (a circuit which detects ultrasound I.e 25kHz here and divides it by 2).
We thought of a signal like what I shown you at the picture(the first post).But i am pretty sure that it does not do his job and cause the audible signal to be distorted unless we have a very small amplitude ultrasound signal
Any solution or trick (modulation or none modulation) which can cause the job to be done is welcomed.

 

[wizard]

Is my last question a stupid question?

 

[audioguru]

Tweeters are extremely fragile. Continuous power destroys them.
Few tweeters have a response above 18khz so 25kHz won't do anything except cause heat in the tweeter.

If you want to receive ultrasound then use ultrasound transducers.

 

[wizard]

Tweeters are extremely fragile. Continuous power destroys them.
Few tweeters have a response above 18khz so 25kHz won't do anything except cause heat in the tweeter.

If you want to receive ultrasound then use ultrasound transducers.

But an Ultrasonic transducer is not able to produce audible sound too (please be noted about what my friend wants to do).

Aside from the transducer, Can somebody let me know how the job is done? I do like to know the response of my last question??

 

[audioguru]

A tweeter will fry if you feed if a continuous sine-wave.
Are you trying to drive away teenagers? Play Mozart classical music.

An ultrasonic transducer resonates at its operating frequency which makes it efficient and loud. Use it.

 

[wizard]

A tweeter will fry if you feed if a continuous sine-wave.
Are you trying to drive away teenagers? Play Mozart classical music.

An ultrasonic transducer resonates at its operating frequency which makes it efficient and loud. Use it.

OK Thanks audioguru,
But I would like to know the response of my MAIN question. Maybe no one could not understand me? If so please let me know to say it in a different why??

 

[audioguru]

Your main question was about modulation of the sine-wave with noise. But it is not modulated, it is a sine-wave with noise added.

Later you want to modulate a 25kHz sine-wave with 12kHz. They are added, not modulated.

Amplitude modulation of a sine-wave makes its signal level increase and decrease. Adding signals doesn't doo dat.

 

[wizard]

Thanks Sir,

Well my friend does not like his AUDIBLE sound to be much changed with that higher freq.

Ok, assuming he has a broadband speaker (Transducer). How is he able transmit both signal with audible signal to has the lowest change when it is heard by the ear?

Can he add a 40kHz signal (maybe low amplitude) with that audible sound to cause the audible sound to have the lowest distortion changed? He says that 'I will be able to receive that 40kHz by an Ultrasonic sensor).

He says that the more the frequency the less the audible sound would be affected (i.e distorted by the ultrasound).

I am not able to see what he is saying by that, so I asked that question here to see if anybody is able to direct him to know what to do to get a such signal?

Apart from the Transducer, can he does the job?

 

[audioguru]

You will not find a transducer that can produce 12kHz and 40kHz at the same time.

Adding a 40kHz signal to a 12kHz signal does not cause distortion unless the amplifier is defective. If the amplifier is good then a tweeter with 12kHz will perform exactly the same when 40kHz is added.

If a 12kHz sound has a 3rd harmonic of distortion added then the distortion is at 36kHz and people can't hear it anyway.

 

[wizard]

You will not find a transducer that can produce 12kHz and 40kHz at the same time.

Adding a 40kHz signal to a 12kHz signal does not cause distortion unless the amplifier is defective. If the amplifier is good then a tweeter with 12kHz will perform exactly the same when 40kHz is added.

If a 12kHz sound has a 3rd harmonic of distortion added then the distortion is at 36kHz and people can't hear it anyway.

Thanks audioguru,

As I said the Transducer is not Important at all (just the possibility).
After my friend's question about his idea, I thought of the possibility of that ASIDE FROM the transducer itself .

That's what I wanted to know. But can you say me why dose 2 different signals will not affect each other?

Do you think using an OP-AMP is the only way to do so.

 

[audioguru]

Two signals don't affect each other if they are added.
They affect each other if they modulate each other.

 

[wizard]

Thanks,
But who can say the reason?

 

[wizard]

"Adding" 2 signals together does not cause their amplitudes to be Added to each other?

 

[audioguru]

"Adding" 2 signals together does not cause their amplitudes to be Added to each other?

No.
Each signal has the same amplitude it had before adding.
On the total signal you can see the high frequency "riding" on the low frequency.

With AM modulation, the amplitude of the high frequency (carrier) is varied by the amplitude of the low frequency (modulation).

 

[wizard]

Oh audioguru, thank you very much,

It makes sense somewhat now.
I would like to know more of Adding, Summing and or modulating signals now specially with your explanation. I made a search via internet but I did not find anything related to our discussion here. maybe I did not use the right keywords? Can somebody help me out for that please? Sorry my knowledge of waves interefernce is weak and I was not able to find a good resource to improve that.

Besides, what is the BEST way to add to signal together? An op-amp or adder or is there any special chip?

P.s. audioguru, When I was looking at the picture you have drown I thought what will happen if somebody Modulates that Added signal too?? What we will have on the output of the modulator?

 

[audioguru]

An inverting opamp is a perfect mixer because one signal does not affect the other. Many signals can be added.

You can add signals then use the added signals to modulate a carrier frequency. That is how radio stations play music and how television signals do it.