MAGIC_WAND

Published:2009/7/15 22:22:00 Author:Jessie | From:SeekIC

This device is easy to use: Just aim the wand at a light source and listen to the tone. Two gates, IC1-a and IC1-b, of a quad two-input NAND gate are connected in an audio-oscillator circuit with R1, the photocell (R2), C1, and C2setting the tone of BZ1. When the photocell is aimed at alight source, its resistance drops and the oscillator's output tone increases in frequency. When either of tone switches (S1 or S2) is presse, the frequency range goes up. Pressing S2 shifts the oscillator into its highest-frequency range. Only one tone switch can be pressed at a time; if both switches are pressed simultaneously, the output stops.



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