Amplitude and Frequency

[duke37]

Dave

You are right, a sine wave would be best but I wonder if it would be any more efficient than a square wave.
A sine wave would need a sine wave oscillator (Wien bridge?) and a class B amplifier with perhaps 60% efficiency.
A square wave could be generated with a 555 or 4093 with only a variable resistance and a capacitor. The amplifier could just a couple of switching fets with 90% efficiency. The transducer must be able to handle the fundamental and also the harmonics.

So it is a choice between nice versus simplicity.

Duke

 

[(*steve*)]

This one?

 

[Electro132]

Dave

You are right, a sine wave would be best but I wonder if it would be any more efficient than a square wave.
A sine wave would need a sine wave oscillator (Wien bridge?) and a class B amplifier with perhaps 60% efficiency.
A square wave could be generated with a 555 or 4093 with only a variable resistance and a capacitor. The amplifier could just a couple of switching fets with 90% efficiency. The transducer must be able to handle the fundamental and also the harmonics.

So it is a choice between nice versus simplicity.

Duke

A transformer can do sine waves as well since it can switch back and forth. I agree with you that sine wave would be the best option but the most simplest option would be to build a square wave.

With the square wave, you can have a Variable resistor added onto the threshold (6) and output (3). But just wanted to know what would happen if i add a variable resistor to Voltage Control (5)?
Also I think the square wave would do just fine if it has the ablility to change its pitch (how deep) with a pot and amplification using variable resistors.

I've always wondered what would happen if i shot out a wave form which was amplified and had a high pitch onto a wine glass. I mean the wine glass would get hit rapidly and instantly giving a probability that it might just break?

 

[Electro132]

Huuuuuuuuuuuuuuh? What does that mean?
Chris

BTW, you obviously missed that Myth Busters episode.

Well i was thinking if there was a bunch of frequencies that could be chosen to resonate rather than just one frequency then the wine glass might break.

But then again, i just realized that if it was just one specific frequency being used and variable resistors were to be used to change the pitch and amplification then it would probably break the wine glass just the same.

 

[Electro132]

The wavelength can be large. Bottom C organ pipes will be 32ft long for half wave but a piccolo is only a few inches long.
The speed of sound is about 340m/s so the wavelength at 6800Hz will be 340/6800 = 1/20 or 50mm (2 inches). Quite within the possible range of a parabola.

Perhaps Electro132 could make a glass ring, record the sound and use Audacity to determine the frequency.

Hey duke37, i've completed the amp and tone part for the wave. The square is using caps in the 22 uf for the IC output and 0.022 uf between the trigger and the negative -Vss. The toner is using 0.004 uf from the output , 0.1 uf for the effect output and 0.01 uf for ground. I've attached some pics to show you guys where i'm at.

As i don't have an oscilloscope or can afford one at the moment, is there any way i can build one to check the frequency of my circuit? Or is there some way i can check using a computer?

 

[duke37]

Your pictures do not help. Draw the circuit (schematic) with chip type and component values and scan or photograph it.

You should measure the frequency of the glass resonance by energising the rim with a damp finger. Use a microphone to get it into the computer and use a program to measure the frequency.

You can measure the frequency of the oscillator by using it to drive a small speaker and doing the same thing with the computer.

Once you have the oscillator running near the right frequency you will need a powerful amplifier and a powerful speaker which can manage the frequency chosen. Use ear muffs.

 

[CDRIVE]

Wow! There's nothing more clever than using a heavily patterned background to really bring out the details of the object you're photographing.

Sorry,.. I couldn't help myself!

Chris

 

[Electro132]

Your pictures do not help. Draw the circuit (schematic) with chip type and component values and scan or photograph it.

You should measure the frequency of the glass resonance by energising the rim with a damp finger. Use a microphone to get it into the computer and use a program to measure the frequency.

Do you think Audacity can measure it? I don't know of any other software that can.

You can measure the frequency of the oscillator by using it to drive a small speaker and doing the same thing with the computer.

By what you say i'm guessing that i attach the small speaker on the oscillator circuit. I just don't understand the 2nd bit - do i need to have another oscillator with a speaker attached to the computer on the other side?

Once you have the oscillator running near the right frequency you will need a powerful amplifier and a powerful speaker which can manage the frequency chosen. Use ear muffs.

I was just thinking maybe sine wave is better for this but i'm pretty sure square waves can do it just the same.

By the way, i've heard some gadgets can produce high pitched sounds breaking glass windows that are 5mm thick. Is the size of the powerful speaker really necessary? I just don't want to buy something large especially if the outcome can be achieved with just a small one.

 

[Electro132]

Wow! There's nothing more clever than using a heavily patterned background to really bring out the details of the object you're photographing.

Sorry,.. I couldn't help myself!

Chris

Lol i know, but there wasn't another table available at the time i took it. At least it doesn't obstruct the other labels of the picture that are visible

 

[duke37]

I use a blue coat as a background for taking pictures.

Have you managed to get a glass to ring with a wet finger?

I have never used Audacity but a review I saw says the autocorrelation function is good to determine the note. I see that some USB oscilloscopes have this function and software defined radio (SDR) also.

Once you have measured the glass frequency, your oscillator with speaker can be tuned to the same frequency using the same method.

You cannot use a big speaker, the frequency will be in the high audio range and big speakers will have cones which are too heavy to respond. Little speakers are easy to burn out.

 

[CDRIVE]

You cannot use a big speaker, the frequency will be in the high audio range and big speakers will have cones which are too heavy to respond.

This is one of the issues I had with the Myth Busters episode. The speakers they used were bird baths,... sized for a flock of Condors!!

Chris

 

[Electro132]

I use a blue coat as a background for taking pictures.

Have you managed to get a glass to ring with a wet finger?

I have never used Audacity but a review I saw says the autocorrelation function is good to determine the note. I see that some USB oscilloscopes have this function and software defined radio (SDR) also.

Hey i've attached the drawing of the components. But still needing to do the test with the wet finger to the glass.

Once you have measured the glass frequency, your oscillator with speaker can be tuned to the same frequency using the same method.

You cannot use a big speaker, the frequency will be in the high audio range and big speakers will have cones which are too heavy to respond. Little speakers are easy to burn out.

Ok i've managed to get hold of a 5W 8 ohm speaker. Do you think that will do or will it burn out?

 

[duke37]

If you keep the input to less than 6V AC, the speaker should be OK.

 

[Electro132]

If you keep the input to less than 6V AC, the speaker should be OK.

Sorry forgot to attach the schematics Lol

Just wanted to know, don't i have a better chance of gaining a stronger signal with more voltage? If i started off the frequency at a low voltage then that will be the starting point of the frequency won't it? Or the voltage doesn't do anything to the frequency just the amp and pitch?

 

[solo2racr]

Do you think Audacity can measure it? I don't know of any other software that can.

This is the one I would use. And it's free. http://www.sillanumsoft.org/

For a driver (or drivers) I would look at peizo tweeters. You can virtually connect these to a wall outlet and they won't cook.

 

[duke37]

Frequency and pitch are the same thing. The frequency will be determined by an oscillator, in your case, the 555. Output level (amplitude) will not affect the pitch.

The 555 will not be able to ouput much more than a mad mosquito. You will need a power amplifier to get sufficient power transfered to the glass. You may need an array of speakers to get sufficient power.

Piezo tweeters are good for very high frequencies but we do not know the resonant frequency of the glass yet.

 

[solo2racr]

Piezo tweeters are good for very high frequencies but we do not know the resonant frequency of the glass yet.

True enough. But I am thinking that it will end up being in a range that a piezo can handle. A quick check found one that shows a response of 1,800-20,000 HZ and 200W rms power handling. The cost was under $2.00/each. A focused line array to a single point at the correct frequency, alternating parallel/series wiring on the drivers to keep the impedance in line with what the amp will handle, I believe, would be a good approach.

The glass can also be tuned be varying a quantity of liquid (water) in the glass.

 

[Electro132]

Frequency and pitch are the same thing. The frequency will be determined by an oscillator, in your case, the 555. Output level (amplitude) will not affect the pitch.

ok cool, i found this mic pre amp to receive the incoming signal to the laptop. One of them doesn't have the values so i might need your help on it. The other one i'm not sure how to calculate the cap needed at the output and also whether i need to attach an amp to it before it goes into the laptop? Check it out and let me know what you think.

The 555 will not be able to ouput much more than a mad mosquito. You will need a power amplifier to get sufficient power transfered to the glass. You may need an array of speakers to get sufficient power.

Piezo tweeters are good for very high frequencies but we do not know the resonant frequency of the glass yet.

Is that with the current values or just the 555 alone? if it has to do with the values then can you help me understand how to increase or lower it from a mad mosquito?

 

[solo2racr]

FWIW........The aforementioned free software (in post 35) also contains a sine wave generator, as well as others (square, sawtooth, etc).

If the goal is to build a signal generator, amplifier, AND break the glass,then the software is only good to measure the resonant frequency of the glass. If the only goal is to sonically break the glass, then there is your answer. Just add a mic to measure the frequency of the glass and a amp and speakers to break it.

 

[duke37]

Try the microphone direct to the computer (through a 100n capacitor), you may not need an amplifier.

A 555 will not handle a lot of power. The resistors and capacitor are there to set the frequency.

The software which solo2racr recommends seems to do all that you want including replacing the 555.