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Topic: Light Controlled Sreamer with 555s (Read 1602 times) previous topic - next topic

Light Controlled Sreamer with 555s

Here's a fun project to make with the 555 chip. It can be built as a stand alone circuit or you can put it inside a doll, toy or whatever! I'm entering this one in the 555 Contest in the Art category.

Here's how it works. When it's turned on, the 555 astable oscillators are activated. One will produce a high pitch squeal through the speaker and the other will blink the LED about twice per second. When you shield the photo cells from light, the frequency of the sound will decrease and the LED will blink slower. If you arrange the photo cells so that they are near the LED, some of the light from the LED will be reflected off whatever is shielding the photo cell. The photo cell will react to the light and raise the frequency while the LED is on, then go back to where  it was when the LED is off. See the video below for a demonstration.

http://www.youtube.com/watch?v=_2o8shevoJw

Here's the project page on Dinofab:
http://www.dinofab.com/screamer.html