Bench Function Generator and Speakers

[waihankan]

Hello,

So, my goal is to make a Chladni Plate using speakers. I'm wondering if I can connect the function generator directly to the speaker. Is it safe to do so? If not, would making an LM386 amplifier help?

Thank you

 

[bertus]

Hello,

The tone generator will likely have a 50 ohms output impedance.
It likely will not be able to drive a speaker directly.
Depending on the needed power, you will need a power amplifier.
The lm386 can only deliver about 1 Watt.
There are more powerfull amplifiers around.
The lm1875 is even capable of 20 Watt output.

Bertus

 

[Delta Prime]

if you're going to be a bear be a grizzly.
How about a piezoelectric actuator acoustic manipulation system.

Controlling the motion of multiple objects on a Chladni plate - Nature Communications

Moving particles on a vibrating plate dates back to 1780s, but it is still challenging to control individual particles in a parallel way. Here, Zhou et al. use a single acoustic actuator and an algorithm to control multiple objects simultaneously and independently for sorting and pattern formation.

www.nature.com

 

[waihankan]

Hello,

The tone generator will likely have a 50 ohms output impedance.
It likely will not be able to drive a speaker directly.
Depending on the needed power, you will need a power amplifier.
The lm386 can only deliver about 1 Watt.
There are more powerfull amplifiers around.
The lm1875 is even capable of 20 Watt output.

Bertus

Hi Bertus,

Thank you for the reply. I will be connecting with a small speaker I believe. Do you think I will need a much bigger speaker for achieving enough vibration needed for the Chladni Plate?
I am a bit confused here as well in this video.

. In the beginning, he said it's an 8ohm 15W speaker. How would LM386 surviving in his video?
Also, I think in my case, the input will be the signal from function generator, right?

 

[waihankan]

if you're going to be a bear be a grizzly.
How about a piezoelectric actuator acoustic manipulation system.

Controlling the motion of multiple objects on a Chladni plate - Nature Communications

Moving particles on a vibrating plate dates back to 1780s, but it is still challenging to control individual particles in a parallel way. Here, Zhou et al. use a single acoustic actuator and an algorithm to control multiple objects simultaneously and independently for sorting and pattern formation.

www.nature.com

Hi Delta Prime,

Thank you for the paper! I'm doing this project in order to do research on Moire Pattern. Potentially finding some relationships between Moire Pattern and Vibration Frequencies. Let me know if you have any thoughts on it!

 

[Delta Prime]

Potentially finding some relationships between Moire Pattern and Vibration Frequencies

Sorry to be the one to tell you, this relationship has been known for quite some time now. The relationships between Moire Pattern and Vibration Frequencies the mathematical relationship governing Chladni patterns involves the vibrational modes of the plate and the nodal patterns associated with these modes.
Moire patterns are interference patterns that occur when two regular patterns are overlaid or superimposed. These patterns arise due to the interaction of the two patterns, leading to a new Interference
pattern.
These patterns result from the standing wave patterns that form on the surface of the plate due to the vibration modes of the plate created by your amplified signal bench function generator signal to your speaker,

 

[Harald Kapp]

In the beginning, he said it's an 8ohm 15W speaker. How would LM386 surviving in his video?

This means only that the speaker can work at 15 W. It does not imply that the LM386 really delivered these 15 W. I'm not going to watch the video, but assuming a supply voltage of 8 V the power output of the LM386 to an 8 Ohm speaker is likely < 1 W.

The BIG difference between the output of a function generator and an amplifier is the internal resistance/impedance:

The function generator has typically 50 Ohm impedance. With an 8 Ohm load it creates a voltage divider 8/58 =0.138. Most of the output voltage creates power dissipation across the internal impedance instead of providing power to the speaker.

An amplifier has a low output impedance << 1 Ohm. With an 8 Ohm load it creates a voltage divider > 8/9. Most of the output voltage is available to drive the speaker.

 

[73's de Edd]

And I'm STILL laughing . . . . . . . at the consideration of an LM386 for the audio drive "taskmaster" .
If it was my "duck to pluck " I would be going at it this way.

The solid mounting of an adequate power speaker to a board with its cone facing straight up.
The cutting and building of the vibration plate from a 12 inch . .or . . so . . . square smooth corrugated cardboard stock.
Use an inter mechanical central coupling of a hollow cardboard tube of like or greater diameter than the speaker voice coil dome.
That couples the speaker voice coil to the dead center of the bottom of the cardboard vibrational plate.
Don't use a soft pliable adhesive use a HARD setting one. My choice would be 4- 90 degree spaced drops of two part epoxy.
Sets HARD !
Later on, the cardboard is sacrificial to be able get in close and remove those 4 drops from the speaker area bonding, as the speaker is needed elsewhere . . .as a speaker again..
On the 4 peripheries of that plate, glue on 4 . . . . . 1/2 in vertically high end strips of cardboard stock, to keep the errant "vibrants" from rolling off the plate sides .
That should be a super light and very mechanically active plate with minimal audio drive needed.

BTW that procedure also makes a quite impressive LARGE speaker, if using a 1/2 or 1 inch thick polystyrene sheet , instead . . . .which is as light as a popcorn fart . . . . and will move a large mass of air.

Thaaaaasssssit . . . .

73's de Edd . . . . .
.