The Clancy unit is a simple 555 Timer chip - can handle up to 15v. But it feeds the voltage directly to the servo without any regulator, so your servo's need to be able to handle up to 7.4 volts. I run servo's off a radio receiver with 2 LiFe's (6.6 volts, nominal but 7.2 volts when fully charged) with no problems. Most modern servo's are rated to 7.4 volts anyway, but some of the real cheap ones (like 10 for $15) have spec's that say 4.8-6.0 volts. So check your servo specs or get more modern servo's.
(Should have specified that the Single Channel unit is a simple 555. The multi-channel ones would have different spec's of course and I've not seen anything on those -- Unfortunely, Clancy has not been on here in a while, but he does have a thread in the Vendor's area under "U/Tronics Control")
I hesitate to post other peoples email addresses, so if you want Clancy's from my address book, PM me.