4h Timing circuit composed of 556

Published:2011/4/14 3:42:00 Author:Ecco | Keyword: 4h , Timing circuit | From:SeekIC

The figure shows 4h timing circuit which is composed of 556 dual time base circuit. To access N8281 divider network in the middle of 556 dual time base circuit, it will get a long time delay without large volume of capacitors. The first l / 2 (556) works in the way of oscillator, the period is l / f. It will produce the signal output in a N / f cycle to trigger the other half 1 / 2 (556) to add the output of oscillator to N divider network. It decides the total delay produced by the dividerto connect the divider to ⑧ pin of the second 1 / 2 (556) input terminal. Delay time is divided in 4 blocks of 30min, 1h, 2h, 4h. If connecting N8281 crossover in series additionally , the total amount of delay can be increased to days or even weeks.



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