Steve - Thanks for your reply - The transformer is from Jameco (www.jameco.com), P/N: 249412. The spec sheet says that I should be getting 8VAC @ 1.6A (I know that is a little over-kill on the amperage, but it is what I had lying around), but I am measuring 9.8VAC across the input to my bridge rectifier. Using a voltage divider (4k7 & 10K), that gets the DC voltage to GPIO.4 down to 4.33VDC. The cap is a 470 uF 25V electrolytic.

Let me know if you need anything else... Thanks!

Atom058