CRYSTAL_TIMEBASE

Published:2009/7/7 7:12:00 Author:May | From:SeekIC

An on-board oscillator and a 17-stage divider compose IC1. By connecting a standard 3.58-MHz, television color-burst crystal as shown, an accurate source of 60-Hz squarewaves is generated at the IC's output, pin 1. Those pulses are then fed to IC2, a 4024 seven-stage ripple counter. Its outputs are connected to different gates in IC3, which is a dual four-input NAND gate. Depending on which position pulse-select switch S2 is on, one of those gates will provide an output/reset pulse of the selected width.



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