I'd consider Brian's remake of the JoeD's timer (it includes a refesh) before tackling the building of the Refresh Circuit.
If you enjoy building circuits tho, the below link shows a refresh circuit I've been using. Altho it shows how to hook up with JoeD's Timer, you can hook it up to any relay that triggers your camera (like one installed on the PIR.
Sounds great Joe D. I have one of your timers and have been well pleased with it thus far. Let us know about your refresh unit. I was planning on ordering a couple more timers from you and I just bought two owl pfs that I would like to use a refresh circuit. If all works well, I would like to have two of them(timer and refresh circuit). What will be the price of the new addition completed and ready to plug into a current setup. Thanks.