Count Down

[drosera88]

I am somewhat new to electronics and any help would be appreciated. What I am trying to build is a 5 LED countdown timer thingy. Basically, I want it to count down, turning off one LED about every 2 seconds, then after that, a buzzer sounds. I also want an easy way to reset it. Originally, I had a complicated design that used capacitors and their charge rates to turn the LEDs off, but it was inconvenient and to be reset all the capacitors had to be discharged. All the LEDs would start fading as soon as you turned it on, which was also undesireable. Im thinking of using a decade timer, but am unsure how to use one properly. Any help is appreciated.

 

[elsafey]

4017 - ok

 

[Russlk]

Use an 8 bit shift register. Parallel load ones into all 8 bits then clock at a 2 second rate to shift right and turn off. Use a LM555 for the clock. CD4021 or 74xx198 or 74LS299 shift registers.