Hey All-

I'm a beginner at circuits so keep that in mind with your responses. If you think I won't get what you are saying, but you can suggest another location to look, that'd be great too.

I am hoping to make a two part project. I want to talk into a microphone and convert that sound into light. In the second part, I want to use a photo-transistor and a speaker to convert that light back into sound.

I've had some help on this, and I think I have all my components down for part 1, but I'm not exactly sure how to connect them all. I'm using surface mount components on a board I mill myself so I'll need to be able to put it all together in Eagle (limited experience here).

As I understand it I'll need**:
-A 4-pin header to connect to a battery
-A microphone, and three resistors, and a capacitor for the sound input
-An Attiny45 microcontroller and a 6 pin header to program it
-A LED and resistor, possibly a MOSFET if the LED is bright enough, for the light output

**Need might be the wrong word here, but these are the components I have.

I've milled boards and stuffed them before, but only by working off pre-set plans. I've never had to figure out what connects to what before and am frankly pretty lost. Any help anyone could give on what goes where on my board would be very helpful. If I get this part done, I'll be back to ask about programming the micro controller, and making part 2.

Thanks much,
FK

 

I think you are off to a wrong start.

Before you start collecting components, designing a circuit board etc. you need to assess your knowledge base. You cannot design with a microcontroller if you have never worked with one and don't know how to program one.

You also need to clearly define your objectives and what you are attempting to do.

Let us take Part 1.

You want to take a signal from a microphone and convert the signal into light. What do you mean by "light". Are you attempting to transmit the sound information via a light beam? What is your light source... lamp, LED, laser? What is your modulation scheme, i.e. how is the information encoded in the light? What is the distance you wish this light to be transmitted?

 

So do you want to transmit audio via light and receive it as the original ?
If so then..

circuit

you need to add a microphone amp to the transmitter.

 

I think you are off to a wrong start.

Before you start collecting components, designing a circuit board etc. you need to assess your knowledge base. You cannot design with a microcontroller if you have never worked with one and don't know how to program one.

You also need to clearly define your objectives and what you are attempting to do.

Let us take Part 1.

You want to take a signal from a microphone and convert the signal into light. What do you mean by "light". Are you attempting to transmit the sound information via a light beam? What is your light source... lamp, LED, laser? What is your modulation scheme, i.e. how is the information encoded in the light? What is the distance you wish this light to be transmitted?

Right, thanks MrChips. You are correct that I don't have a lot of experience so I probably didn't give all the information.

I have "programmed" microcontrollers before, but I followed very simple instructions using Arduino with code I did not write. So I guess I should ask how to do that too, correct.

My light source is an LED. I don't know my modulation scheme, and was hoping for help there too. The light does not need to travel far, a meter maximum, and like I said, I'll be asking for help on the receiver unit as well.

 

Is this for a light show, science experiment, or what? The basic goal is simple enough, but the exact use does affect the best way of doing it. Understand, their are several ways to skin this cat.

 

Is this for a light show, science experiment, or what? The basic goal is simple enough, but the exact use does affect the best way of doing it. Understand, their are several ways to skin this cat.

Thanks Bill. This is for a science experiment. I am a high school physics teacher and we'll use this in our Waves/Energy unit as a demo of waves changing form. I've got the physics down, but having never built circuitry or programmed, I'm finding myself as lost as my students seem sometimes.

FK

 

I really like the schematics posted by Dodgydave. Have you reviewed that project and what do you think? If you want to build that, I'll breadboard it and work through it with you.

 

I really like the schematics posted by Dodgydave. Have you reviewed that project and what do you think? If you want to build that, I'll breadboard it and work through it with you.

What I understand of the board does look good, but I was hoping to do some modulation with a microcontroller. It's possible I'm not reading the schematic right, but I don't see that in there.

FK

 

Let's back up for a moment

I am a high school physics teacher and we'll use this in our Waves/Energy unit as a demo of waves changing form.

Can you elaborate what you are attempting to do?
Sound waves hit a microphone. What happens next?

 

Let's back up for a moment
Can you elaborate what you are attempting to do?
Sound waves hit a microphone. What happens next?

Acoustic wave -> microphone -> electrical waveform -> input circuit -> μC -> output driver -> LED -> modulated light beam

Is my understanding. Now that being said, I don't (yet) know how to do that.

FK

 

Don't worry about the electronics part we can handle that.

How does this demonstrate waves changing form?

 

Don't worry about the electronics part we can handle that.

How does this demonstrate waves changing form?

It's basically a rudimentary cell phone. Audio waves are turned into EM waves, transmitted, received, and turned back. Part 1 is just changing the audio to light. Part 2 will be changing the light back to audio.

FK

 

Hah! I think I'm getting the picture. This is not a physics demo on acoustic waves.
This is a conceptual demo of information processing, converting sound waves to electrical to light and back again.