How do I make a battery powered LED react to sound?

I am trying to create a prop that is activated via either light (light sensor triggers the action) or push button. I would like to have an LED and small speaker with a prerecorded sound activate with either light or a push button activation. That way, when the circuit is activated, the LED will turn on and the sound will play. Then, once the sound has stopped, I'd like the LED to turn off. I would also like this to be as small as possible as I am working in a very limited space and I'd also like it to be battery operated. By small, I am working in a jar with a 2 inch diameter lid from Ikea. The jar will be fogged so most of the wiring and such will be hidden but I would like it as small as possible. I'm thinking a speaker from Build-a-Bear since they have the small puck recordable speaker that I can record my sound on. However, I have no idea as to how to get the LED to react to the sounds coming out of the speaker. I want the LED to light up as if it were talking. (I basically trying to make Navi from Zelda in a jar for a friend's Link costume for Comic Con).

Any thoughts, suggestions, or insight would be helpful.


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dog digger6 years ago
I have a tutorial on how to do this in my ultimate LED guide. Here's a link to it
DIY Micah (author)  dog digger6 years ago
Thanks digger! I actually ended up wiring up a circuit pretty much identical to the one you have in your 'ible. Thanks though!
dboone6287 years ago
Connect the audio signal to the base of a transistor. The button, resistor, and LED should be connected in series with the collector of the transistor.
Here's a kit that runs off a 9V battery. The kit is cheap, but there's also a schematic right there on the page that you might be able to use for a scratch build.
excaza7 years ago
These two instructables do something similar to what you're looking for:
DIY Micah (author)  excaza7 years ago
I saw both of these but they appear to be wall powered. I wanted something that will be battery only powered. Any thoughts?
Maybe put the led in-line with the speaker(if its a low enough power).
Develop an audio-variable resistor and rent/sell the patents for lots of money.