Main content
Course: Exploratorium > Unit 4
Lesson 3: Turn Light into Sound- Light into sound introduction
- Materials and tools
- Build and test the receiver
- Build the transmitter
- Construct the parallel circuit, put it all together
- What's going on: Turning sound into light
- Engineering challenge
- Turn light into sound: Complete activity guide
© 2024 Khan AcademyTerms of usePrivacy PolicyCookie Notice
Engineering challenge
What can you do to improve this system or explore further?
Some ideas:
Which LED works best? Try several different LEDs and find out which results in the clearest sound or transmits the sound farthest. Does the relative brightness of an LED affect the results?
Cancel the noise. It can be hard to use your system in a room lit by fluorescent lights because the lights flicker on and off, producing an annoying hum. To get rid of the hum, you can make a noise-canceling receiver with two identical solar cells:
1. Hook the solar cells together in a series, attaching the positive side of one to the positive side of the other. Attach the amplifier to the two negative terminals.
2. Shine the light from the LED on only one of the solar cells while the room light shines on them both. The signal from the LED is converted to electricity by one of the cells, and the signal from the room light is converted into electricity by both of the cells. Because the cells are hooked together so that they oppose each other, the two signals from the room light cancel each other out. This allows you to hear the radio signal in a noisy environment.
Want to join the conversation?
How about hooking up a laser pointer would that work?(5 votes)
"Laser pointers" can't just be just be used because they have an integrated power supply unit but a few modifications can make that work.
But for the intensity and all part.......I don't know.(1 vote)
sir i have made the project but the sound volume is very low... how can i increse that....?(3 votes)
Probably by using a brighter LED, or perhaps by using a more sensitive solar panel...(3 votes)
where can I get the answer. :D :b(2 votes)
Figure it out! (im not trying to be rude)(5 votes)
Why was static introduced as the light sensor was brought closer to the LED?(2 votes)
inverse square law. the closer you get the more noise is generated due to the square of the distance(1 vote)
Wait Made a new design went to 900m(1 vote)- 900 seems a bit absurd for this system. Switched to a laser diode?(2 votes)
- can we use a low cost LASER light instead of LED and use an earphone instead of speaker and use it for somewhat reasonable distance say within a hall. is it possible?(1 vote)
- Yes, the one that I am working on has been going about 3 feet, but I am trying to get it to go 10 feet.(2 votes)
- Can You use a better radio? I Made it to work to 3metres !(1 vote)
- Presumably the radio is am? Can we make a receiver for light, uv, x, and even cosmic radiation?(1 vote)
I will put the led and the solarpanel in a light seald environment, like a boks or somthing, is that cheating? I will also try the solution above.
Off to the hardware store.
Thanks for a great video from Denmark.(1 vote)
OK, ok, ok
You are want to increase your range of your data through light you are going to need to increase your optics - focus. So to start with all extraneous frequencies need to be blocked the best way to do this is by covering and grounding the cover. Secondly a stronger light source will be needed to transmit data over a longer distance; lastly the clarity of the data is a must.
Optics
Why reinvent the wheel I would just use an old telescope, old rifle scope or spotting scope with metal casing they have focusing capability already.
• paper rolls (panted white gloss on inside)
• copper wire bradding (for grounding)
• round mirror (paper roll end)
• flat black cardboard insert (1/4-3/8 hole centered)
Stronger Light Frequency
I would use a green hand held laser light (I think, green transfers more data although red is easier to see in daylight) to high power laser depending on the distance.
• paper rolls (panted flat black on inside)
• copper wire bradding (for grounding)
Clarity of the Data
Simply put “garbage in garbage out”, so if you want to get High Fidelity out you are going need to put High Fidelity in. Cleaner data then the static filled AM/FM MHz can be transferred say MP3, CD or even DVD. The audio/video booster can be upgraded too; a chain is only as strong as its weakest link.
More later(1 vote)
- Maybe for the first problem use something that the radio waves could bounce off of, somthin like a steel plate? would this work?(1 vote)