Need reliable electrical or mechanical 24hr timer

[wannab]

It needs to perform at least 50 cycles with a cumulative error of no more than [+\-] 30 minutes. This is for a home project.

Any suggestions of components?

 

[russ_watters]

Cumulative error over what period of time?

 

[wannab]

50*24 hours

 

[Travis_King]

I'm not sure I understand...why can't you use a clock (either electrical or mechanical)?