Rob, typically electronic components have a bit of leeway, but in order to perform as needed, you're better off keeping within specs. In other words, the thing may start working at 2.2 volts, but you can't be sure. I don't know about your motor, but I was amazed that my 24V motor started revolving right at, or slightly under 1 volt. It would work if you remembered to crank up the voltage above 3 v as soon as you observed everything was running OK, and subsequent slow downs would only account for, what, under 100 turns or so, which is pretty small compared to 4000, 8000, 10,000 turns we're typically dealing with. That said, however, I kind of suspect you're a bit OCD like me, and just wouldn't feel right knowing that there is some error there. That said, there is another simple integrated circuit that can use a 9V battery to provide a steady 5 volts**, or for that matter, I think a couple of D size Duracells in a Radio Shack holder would provide you more than a years' service of 3 volts, either one of which would work fine. As pointed out earlier, just don't forget, and use worn out batteries, and end up halfway thru a wind, with a dead counter trigger. 5v DC wall wart is the solution to that concern. **of which I have a spare, and would be happy to send you. PM me if you want one. I wannt wean you off that mag switch. EDIT: Also, it occurred to me that since you've already got 3 volt power supply just sitting there in your Cub counter. . . .hmmmm? Again, somebody more knowledgable like GN or Jim might know how, or if, this can be tapped to run the Hall sensor in addition to the counter~~ Absolutely right GN. I was just proving more of my electronic ignorance. Or maybe I'd just been reading about voltage pumps, a concept I still have yet to get my feeble brain around??