level-8 touch volume controller of 74L194 circuit

Published:2011/5/11 4:56:00 Author:chopper | Keyword: touch volume controller, level-8 | From:SeekIC

As shown in figure is a level-8 touch volume controller of 74L194 circuit.Multivibrator type oscillator,shifting register,touch control circuit,impedance inverter circuit form the circuit.The oscillatory frequency of multivibrator type oscillator composed of IC1(555) and R18,R19,C2 is f=1.44/(R18+2R19)C2,and the corresponding frequency of parameter in the figure is about 2Hz.The outputing square signal acts as shifting clock pulse of IC2,IC3.IC2,IC3 are bidirectional shift-registers 74LSl94,and they two concatenate to be a shift-register.IC2,IC3 will be cleared when it meets a boot-strap,and Q0～Q7 are all low level.The circuit is unchangeable and the volume is the least.The S0(pin ⑨)of IC2,IC3 is high level when we touch the sheet metal A by hands,and IC2,IC3 reach a serial rightward shift,makingLED0～LED7 illumine one by one.At the same time,with the electric current,LED8 reaches a staged growth and becomes more brilliant.The resistance of corresponding photoresistor Cds decreases,and the volume inceases gradually.The range of fluctuation is controlled by the time of touching A.When we touch metal B,IC1,IC2 will reach a serial leftward shift because the the S1(pin ⑩) is high level,makeing the volume diminish gradually.



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