Sound to Light - Simple? - Page 1
Forum section: electronics / projects

author: 0528203
author_rank: Newbie
timestamp: February 28, 2014, 10:09:22 pm
content: Hi Chris here, this is what most of you is thinking is a pointless question and that I should of searched the forums more and before you click back I have and no one asks the direct question that all these internet pages fail to give a simple answer to so to the point, the project.Build a sound to light circuit...That uses 12 volts (car battery).Doesn't use a microphone.Isn't just connecting the strip to 2 speaker wires.Works on a car stereo.Doesn't distort or affect the sound signal its usingCould be expanded to use a selection of filters and microcontroller for lighting patterns.Sound simple go try it and let me know what you turn up im pretty sure someone can manage this and I strongly recommend testing on a car stereo because sometimes you try it on say a pc aux out and it will work perfectly try it on a car audio output can prove rather tricky, I have tried this using as much as my head can find on dear old google but am turning up empty thanks in advance,Chris.

author: Rerouter
author_rank: Super Contributor
timestamp: February 28, 2014, 10:19:45 pm
content: use an op amp with say a 100K input impedance and a small AC coupling cap from the divider to get it in the range you want (amplifiers can be much higher than 12V in cars), then use a voltage to current config on a second op amp to vary the brightness in a more predictable manner?realistically I'm guessing you will want to use a low pass filter before the voltage to current stage else it will be varying faster than you can see and flickering, especially on the 20+ Khz noise injected into the amplifier by the cars power rails,

author: rentner
author_rank: Regular Contributor
timestamp: March 01, 2014, 02:37:07 am
content: You should use a voltage regulator, resistor in series and a big capacitor, if you want absolutely perfect DC. That is not efficient at all, but it gives you the cleanest DC you can possibly imagine.To recieve it you could just use a photo resistor. Remember to decouple the signal to remove signals caused by light changes. For that purpuse infrared is prefered of course. And IR Recievers are also not that expensive. But if they are fast enought? o.OI just would use an AM transmitter, which actually is very, very simple.At first: get your AC from the audio to a DC potential (biased that way, that 0V on the input gives you exactly 1/2 of the supply voltage). You can use Class D or Class A for that. After that you have to use a combination of inductors and capacitors on resonant frequency. To keep the frequency stable you have to use a quarz oscillator. But please don't ask me, how to recieve AM - I realy don't know it, because I never build a reciever. Just a transmitter.Remember: High power transmitters are illegal almost everywhere! Respect the law of your country or the cops might take care of that...What I want to say: A radio wave transmitter always is better, since it is quite jelly bean.I will just search for a working circuit.Edit:Did not find something helpful on google. If you wait till tomorrow, I could give you a circuit of this. Before that please tell, if you are even ok with a transmitter, that does not use light.The problem with light is, that it does not work through anything but air or water or glass. Also, Light recieving devices are usually quite slow - see Opto Isolators for that problem. Most of them are not fast at all!If you want clean sound, you have to use a very stable signal, which is very difficult with light, because many things can stop light from actually hitting its planned target. Also other light scources are a problem, because they can interfer with it. A remote for the TV for example does not need a perfect signal, it just needs a signal. Audio with distortions for example sounds horrible... That is the big problem.You can make a High Fidelity light transmitter, but the reciever is more difficult.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 01, 2014, 03:11:15 am
content: Why? To what end?Is this for actually transmitting audio (to later be converted back to acoustic sound) over light, or is this a light organ type thing?Tim

author: Unknown
author_rank: Unknown
timestamp: March 01, 2014, 03:34:22 am
content: Quote from: T3sl4co1l on March 01, 2014, 03:11:15 amFrom the OP's mention of "Isn't just connecting the strip to 2 speaker wires" and "Could be expanded to use a selection of filters and microcontroller for lighting patterns", it reads to me like a light organ type thing.In which case I don't see why you wouldn't start with a good ol' LM391x, or the even more basic single-transistor design beloved of newbs on YouTube, along with a properly filtered & regulated power supply...(That's 3 full stops rather than an ellipsis, because the OP's post appears to be missing a few.)