555 TV starting up timer circuit

Published:2011/6/15 3:34:00 Author:TaoXi | Keyword: 555, TV, starting up, timer circuit | From:SeekIC

As the figure 14-13 shows, the timer is composed of the benchmark pulse generator, the reservation time limit interlock switch, the counter and the driving circuit. And this device can be used to control the children watching TV time. The time limit has five levels: the limit time of K1 is 40 minutes, the locking time is 280 minutes; the limit time of K2 is 80minutes, the locking time is 240 minutes; the limit time of K3 is 160 minutes, the locking time is 160 minutes; the limit time of K4 is 280 minutes, the locking time is 40 minutes; if you do not press K1~K4, the limit time is 320 minutes. The astable oscillator is composed of the IC1 (555) and R1, RP1, C1, the oscillation period T=0.693(R1+RP1)C1, the T of the figure parameter is about 40 minutes. The output of it can be used as the count pulse of the counting circuit IC2.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/555_TV_starting_up_timer_circuit.html

Print this Page | Comments | Reading(3)