PhotonWrangler
Flashaholic
I ran across this article from instructables.com recently. The author discovered that some of the popular flickering LED tea lights are actually driven by a sound chip, the same kind that they use in musical greeting cards. Apparently the square waves that normally drive a piezo speaker can be used to drive an LED as a poor man's PWM to create the flickerng effect. The unit in the article was found to be playing Beethoven into the LED! What a clever idea.
So I was inspired to open up a little halloween LED flickering candle to see if it was based on this principle also. Before opening it up, I decided to hold it close to an AM radio (tuned to a quiet spot on the dial) to see what would happen. When I turned on the light, I heard a loud braaap...braaap...braaap from the candle. Hmm, maybe I'm just hearing the clock frequency, so I decided to take it apart so I could clip a headphone directly across the LED.
It turns out this particular candle has three distinct LED chips in it, and sure enough, there were four wires leading from the driver board to the candle's tip.
So I clipped the headphones across each of the three circuits, and I heard... braaap...briiipp...braaap.
Bottom line? If you have one of the tea lights of the type shown in the article, place it near an AM radio, or hook a solar cell to the mic input of an audio amp and illuminate it with the flickering candle. Let me know if you hear music!
So I was inspired to open up a little halloween LED flickering candle to see if it was based on this principle also. Before opening it up, I decided to hold it close to an AM radio (tuned to a quiet spot on the dial) to see what would happen. When I turned on the light, I heard a loud braaap...braaap...braaap from the candle. Hmm, maybe I'm just hearing the clock frequency, so I decided to take it apart so I could clip a headphone directly across the LED.
It turns out this particular candle has three distinct LED chips in it, and sure enough, there were four wires leading from the driver board to the candle's tip.
So I clipped the headphones across each of the three circuits, and I heard... braaap...briiipp...braaap.
Bottom line? If you have one of the tea lights of the type shown in the article, place it near an AM radio, or hook a solar cell to the mic input of an audio amp and illuminate it with the flickering candle. Let me know if you hear music!
