Hello Dave
F84 does not have BOD . . .
I have used a 100uF cap at the input of 7805 and a 1uF at output.
The schematic is like the one below
<center><img src="http://josepino.com/pic_projects/led_clock/JP6282.gif" alt=" Led Clock Schematic "></center>
The processor resets randomly or just locks up . . .
I'm using a electronic 12v adapter to power it (SMPS type).