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this is an LED Blinker circuit, which is very simple to make and consists of very few components. ie an 8 ohm speaker, an LED and two 1.5 v batteries AA size. this circuit can be used in Christmas trees, the LED blinks according to sound, speaker acts as a mic here..... blinking varies with speakers
My LED remain ON all the time and would dim very slightly when I flicked the speaker with my finger. I tried a 4, 8, 16, and 64 ohm speaker, both in its suggested polarity and reversed polarity.
Did I miss something simple?
I will do some more experimenting and see what I can find out :)