ES-30A     2-colour LED Knight Rider Running Lights Kit
( DC 9V)

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This kit creates an interesting visual effect of a "lighted" ball (LED) 1-row of LED's swinging left & right, changing colors with direction continuously. The "ball" emits green light as it goes from left to right and changes to red on its way back. The LED used in this kit has 3 terminals and it can produce red & green light.  Transistors (Q1 & Q2) form a transistor-transistor astable circuit that  generates square wave which we use to increment the decade counter IC ( IC1). The 10 outputs of IC1 switches to logic high sequentially & continuously (from 0-- 9) as the counter is running. The running speed of the LEDs can be varied by adjusting the trim pot (preset) VR1.