Anyone here that ever been to any Countdown party, such as the New Year countdown party at Times Square? Yep, if you did then you’ve very familiar with the gigantic energy-efficient LED countdown ball at the Times Square.
If you thought that it’s a tough work to develop the countdown timer by your own, then you should think it again. Today, you’ll have the opportunity to build a seven Segment LED Countdown timer and this project is easier than any others are.
Here is a countdown timer that based on the versatile PIC16F84A with so many practical applications. The time range can be adjusted between 1 second to 999 seconds, but for taking an example, the timer is being set to the 3.00 minutes count down and it’s ready to be started anytime you want.
The PIC16F84A is running on 4.00MHz using crystal or resonator, it won’t cause any critical to the circuit since it only runs for a few minutes. When time is over, the sound output will be situated in “active HI” condition for 1 second. The active HI outputs to drive the three displays common + is perfect to drive an NPN-PNP set of high side drivers.
We recommend EasyEDA for circuit design and PCB prototype