CD4510 and CD4511 based 9 Seconds Countdown Timer by 7-SegDisp

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CD4510 and CD4511 based 9 Seconds Countdown Timer by 7-SegDisp

When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.

When the switch is opened, the timer produces an approximate 1 second clock signal, decrementing the counter until the 0 count is reached.

When the zero count is reached, the ‘carry out’ signal at pin 7 of the counter moves low, energizing the 12 volt relay and stopping the clock with a low signal on the reset line (pin 4).

S:electronicsuite.com


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