Elenco LIGHT - Manual (Page 69)

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Project 148 Blow On the Light
Project 149 Blow Off the Light
Build the circuit and turn on the slide
switch (S1). Set the lever on the adjustable
resistor (RV) to the top. If the white LED
(D6) is on, move the lever on RV until the
LED just shuts off. Now blow on the
microphone (X1) to turn the white LED on.
The microphone is a resistor
that changes in value due to
changes in air pressure on its
surface.
Build the circuit and turn on the slide switch (S1). Wait for the white LED
(D6) to come on. Blow into the microphone (X1) to make the white LED
flicker. If you blow hard enough, the LED will turn off for a moment
.