After years of accidentally leaving my chronograph on, and [consequently] having to buy 9v batteries like chewing gum, I finally decided to improve my life with a 10 second Google search. I found this; an AC Adapter to replace DC 9V batteries. Many of you may already have such a thing, or have known about it. But, I guarantee there are several other guys reading this right now have an "aha" moment. 
http://ecx.images-amazon.com/images/I/615nevO%2B%2ByL._SL1000_.jpg
And, here it is hooked up to my ProChrono:

And, for anyone interested, here are some more details re: the setup.

The Whole Shebang:

Uprange (note the [entrance] door has a combination keypad to enter. I close that door when I am shooting):

Downrange:

http://ecx.images-amazon.com/images/I/615nevO%2B%2ByL._SL1000_.jpg
And, here it is hooked up to my ProChrono:

And, for anyone interested, here are some more details re: the setup.
- Compressor is an Omega Super Charger
- Air Tank is a 4500psi Carbon 75 (bought off eBay 5 years ago).
- pellet trap is DIY - cardboard box + rubber mulch + duct tape
- Chronograph is the ProChrono ($100) with IR light kit ($60) (light kit is AC powered)
The Whole Shebang:

Uprange (note the [entrance] door has a combination keypad to enter. I close that door when I am shooting):

Downrange:
