This could possibly be used to measure the wavelengths (frequency??) of different lights. Instead of having the output hooked up to a speaker, hook it up to an (ohm meter??) or something else that could make sense of the electrical pulses coming from the project.

Then…find a way to record and reproduce the frequency, send it to an optical output, and see if it matches the original light input.

If this could be done, and the wavelength (frequency?) could be changed to produce different light patterns or colors. Then your venturing into something that certain sectors of the government might be interested in.

Posted at 11:23 am on Jan 4th, 2009 by Brownsy67

wat?

Posted at 11:35 am on Jan 4th, 2009 by huh?

Way back in 8th grade (I’m in college now), I did a science fair project on this called “Light Into Sound”. I made this circuit and did some experiments using different light sources, noting that our ears can hear faster than our eyes can see. I was the only one who didn’t take the easy way out and do some bean plant growing. It was a fun project, but I got a B for my grade while everyone else (who did plants) got an A, only because my teacher didn’t believe that I made the circuit myself.

Posted at 11:38 am on Jan 4th, 2009 by mcclanahoochie

@Brownsy67

Yea, they could shift infra-red into a sort of.. lovely green colour and call it… night vision.. or maybe even do it with thermal frequencies and call it.. thermal vision..

Posted at 12:51 pm on Jan 4th, 2009 by Steve

reminds me of a drug i took a while ago.

….What?

Posted at 1:01 pm on Jan 4th, 2009 by Arthur

@mcclanahoochie: [only because my teacher didn't believe I made the circuit myself]

People keep asking why I never went back and finished my degree after losing my scholarship because my GPA slipped to 3.49. This kind of crap had a lot to do with it.

/derail

Posted at 3:27 pm on Jan 4th, 2009 by localroger

@mcclanahoochie

I made a similar device back in Junior High (been awhile… I’m a PE now.) (It was a light wave communicator to be specific.) I entered a science fair, and got 3rd place. First place was some bean growing project. I later found out that I got 3rd instead of first because the judges weren’t sure if I had actually built the circuit.

Posted at 4:18 pm on Jan 4th, 2009 by Adam Ziegler

Fun project :)

“This could possibly be used to measure the wavelengths (frequency??) of different lights” This would require very high-frequency sensing, while this is working with low-frequency variations like 50 Hz / 60 Hz mains hums and remote blinking.

“our ears can hear faster than our eyes can see” I understand what you’re getting at, but I feel like it’s worth clarifying that this doesn’t mean our ears get more information. Our ears hear the amplitude of many different frequencies simultaneously every moment from two perspectives, while our eyes see only three frequencies but at many points (again, from two perspectives). Persistence of vision keeps us from perceiving high-frequency changes in light, but that’s just because our eyes are specialized in a different way than our ears.

Posted at 4:20 pm on Jan 4th, 2009 by Kyle McDonald

wow. look at all the people here who got bumped from an a for a science fair project because the judges deemed it impossible for a student to make a circuit like this, eventhough building the circuit is the simplest part of it. i’m glad i’m not alone in that situation!

this is a very nice, basic circuit. glad to see it here.

Posted at 6:34 pm on Jan 4th, 2009 by Josh

reflect a laser on a window some 10 feet away ..
place this converter so that the reflected laser falls on the photodiode.

Posted at 9:22 pm on Jan 4th, 2009 by spyman

My first thought was ‘cat /dev/video0 > /dev/audio’

Posted at 11:00 pm on Jan 4th, 2009 by Urza

i cannot imagine what is so special about this circuit. it converts light intensity variation at the photo diode to current variation feeding into the speaker. it has nothing to do with the wavelength of the light! what is becoming of hackaday!? and all these people about not winning first plce in a science fair..boo hoo! grow up for heavens sake!

Posted at 12:49 am on Jan 5th, 2009 by wtf!

Someone should put it next to a sound-to-light converter and run away.

Posted at 4:19 am on Jan 5th, 2009 by Haku

This circuit is experiment #12 in the Radio shack 2000 in 1 electronics kit.

Glad to see that for 2009 we lowered the bar for hack a day submissions.

Next up: A transistor is used to increase the power switching load of an IC!!! It’s a MIRACLE!!!!! What a Uber Haxor!

F34r my 3|173 h4(k1n6 5k1||5!!!!0n3!

Posted at 4:54 am on Jan 5th, 2009 by fartface

There was a tv show called rough science in which they created something similar. They took a can and covered it with tin foil and reflected the sun off it to a photodiode a considerable distance away. If you talked into the can it vibrated the tin foil which in turn was picked up by the photodiode and transformed back into sound waves. It was a nice concept that seemed to have lots of possibilities.

Posted at 7:27 am on Jan 5th, 2009 by gordon

@fartface

I had that kit too, it was awesome!

Posted at 11:46 am on Jan 5th, 2009 by dan

I believe I remember building this when I was about 10. I think it was in the Forest M. Mimms engineers mini-notebooks sold at Radio Squack. Still an interesting project, but surely not worthy of Hack a Day. :(

Posted at 6:23 am on Jan 6th, 2009 by Tetrafluoroethane

This, with some probable modifications, can be beautifully used by disabled people.

Posted at 11:58 am on Jan 7th, 2009 by cacovsky

a quick, simple way to hear modulated light – get a moderately sized photovoltaic (solar) cell and solder a 1/4″ plug on the end… plug into a guitar amp, and voila!

Posted at 9:44 pm on Jan 10th, 2009 by eric