# Simplest and cheapest possible noise generator circuit

Discussion in 'General Electronics Discussion' started by pansyradish, Sep 24, 2012.

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Sep 24, 2012
Hi all. I'm pretty novice with circuit design, but starting to learn. (and brushing up on everything I've forgotten!)

I'm working on an art project where I need to build up about 30 circuits that will, when connected, just make a noise. any old noise. in fact, the messier the better. It really doesn't matter at all what it sounds like, just needs to make a sound.

Can you folks help me come up with ideas for the simplest (and cheapest) possible circuit to do this? Is there a way that I can just introduce a single component with a battery and speaker that will fluctuate the current enough to buzz the speaker?

Thanks!

2. ### CocaCola

3,635
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Apr 7, 2012

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Sep 24, 2012
of course, now that i'm thinking about it, I may as well just have one speaker and then each of the circuits that are being connected running in parallel.

that would work, right?

another aspect of this is that the connection will be happening with the current running through a person - with a performer touching two different items to complete each circuit. so i suppose that will provide something of a variable resistance element? i'm hoping that that will vary the tones coming from the speaker.

all ideas/thoughts are most appreciated! thanks!

4. ### BobK

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Jan 5, 2010
Noise in electronics has a very different meaning from what I think you are looking for. Think of an FM radio tuned between stations. This is what electronic noise sounds like. Is
this what you mean, or something else?

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Sep 24, 2012

Hey, thanks! So - you think I actually need to buy buzzers for this to work? Or, perhaps one buzzer with one speaker and then, as I just posted, have the additional circuits running in parallel to that?

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Sep 24, 2012
Yes. You're right. I just mean sound. ANY sound.

7. ### BobK

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Jan 5, 2010
Well the simplest sound to make is, as CocaCola already said an oscillator. This puts out a sound of a specific frequency. An oscillator circult could easily be designed to have it's frequency controlled by resistance of a human touching two conductors. A '555 timer would do this easily.

Bob

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Sep 24, 2012
Great, thanks!

So - what if I follow this, but instead of the 56K resistor I use the parallel circuits that will go to the body?

9. ### BobK

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Jan 5, 2010
That should work, though you might have to change the value of the capacitor to get the sound into the right frequency range. The resistnace you get from the body will depend a lot on how much pressure you put on the electrodes, which might be a desireable effect.

Bob

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Sep 24, 2012
Awesome. Any way you can see that I could simplify this?

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Sep 24, 2012
Oh! Sorry - I should have gone back to this earlier. This oscillator circuit actually does look even simpler and I could try just replacing the resistor with the parallel connections similarly.

OR - I was also wondering about just using a buzzer, hopefully finding one that the tone will vary depending on the resistance.

I'll play with all this stuff and let you all know how it pans out if people are interested.

I'm also concerned that I know that bodies have high resistance, though I'm willing to cheat it by running a wire right next to the contact point if necessary.

Thanks again.

12. ### CocaCola

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Apr 7, 2012
Why do you need simpler? The 555 circuit it pretty darn simple... If you are doing a run of 30 of them, that is enough to justify a run of professional PC boards... Assembly of those 30 will only take a few hours, maybe a day if you take your time...

If you really want to cut cost the 555 circuit is easy enough to do leg to leg wiring on an upside down DIP chip...

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Sep 24, 2012
Yep - you're right. I'll just try a 555. Also maybe play around with buzzers to see what might be good in this piece.

Thanks again.

14. ### wingnut

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Aug 9, 2012
Here is a possible 555 circuit that could be modified for your need.

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