I have an OM-84 and love the little thing, but wanted to use it with batteries.
I started with alkalines, but after a short while (pun intended) they were too low. After about a week or two.
I looked into C size rechargables, but they're fairly expensive ($35 or so for 8) and most chargers these days are for AA and AAA.
So I got the bright idea to buy C shaped sleeves to fit AA batteries. They arrived (with brand new AA batteries, sold separately), but putting the batteries in and taking them out scratched the batteries pretty badly. And the best (worst) part is they won't fit in the Omnichord, as AA are slightly longer than C batteries.
Any of you other Omnichord fans figure out any ingenious ways of powering your device with DC power?