555 timer

[rukid88]

Hi
I'm working on a project.
I want to have a time for two days. I am limited to 555 timers only can u please help me.
I was thinking to have a binary counter and count up when the signal is given and then when it gets to two days a buzzer goes off

Thanx

 

[Russlk]

Good approach, check out the CD4521 24 stage binary counter. It has a built-in oscillator, but you can drive it from a 555 if you want. The CD4045, 21 stage binary counter could also be used and may be more available.

 

[rukid88]

Duos any one know the formula for what kind of capacitors and resister I will need for say an hour or two.
Thanx

 

[seeker]

Hi rukid88,

Here are a couple of links that might help:



This one has a link for a nice little timing calculator

**broken link removed**

Good luck with your project!

 

[rukid88]

thank you very much this helps plenty