MELODY_SOUND_TO_LIGHT_CIRCUIT

Published:2009/7/13 23:43:00 Author:May | From:SeekIC

A method of synchronizing a simple light show to a musical chip is given by the circuit diagrant shown. Here, a display of eight rows of four LEDs advances with each musical note. IC2 is a UM66 three-pin melody chip selected to generate the desired tune.When power is applied to IC2, the sequence plays once and then stops. Power must be reapplied to initiate a further rendition.IC1 is a 555 astable, which will constantly reenable the tune chip and repeat the melody. However, the maximum supply voltage of the UM66 range is 3.3 V; hence, a simple zener-diode supply based around two 500-mW 2V7 types (D1 and D2) is used. TR1 is a directly driven transistor amplifier and the melody is played through loudspeaker LS1. Each musical note, when present, also biases transistor TR2 on, which shunts capacitor C2 to ground. In the absence of a note, C2 charges, which causes op amp IC3 to change state at a point determined by preset potentiometer VR1. The output from IC3, pin 6, provides a clock pulse for IC4, a 4022 divide-by-8 counter. Its outputs drive a buffer transistor sequentially to illuminate a series of four LEDs. The light display then advances with each note.



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