The 555 timer circuit of independent adjustable on/off timing

Published:2011/5/30 20:52:00 Author:Borg | Keyword: timer circuit, adjustable | From:SeekIC

See as Figure 12-19, the circuit is added with a IC4 non-steady multi-resonate oscillator and IC5 counting circuit on the base of Figure 12-18, but the working principles are the same. The general timing of fan running is still decided by IC2 whose Q12 point (1-pin) remains in a low LEV during the time, but the switch of ON/OFF has something to do with another input B of NAND 4. The connection method of IC4, NAND 2, IC5 and NAND 3 decides that IC3 and IC4 can only work in turn, which makes the NAND 4 open and close now and than, and the fan runs intermittently.



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