Copy and Paste down at time interval

[mcp77]

Hi

I am a very basic excel user and need help with some VBA please :-)

I would like the value in cell F3 (which changes) to be copied and pasted down to F4 at a 30 sec interval, at the next 30 sec interval the value in F4 would move to F5 and a new "latest value" posted from F3 TO F4 and so on.

Ideally would like a start and end time, so only does the function between these hours and is it not in these houses it pauses.

Thanks in advance for any help.