Does anyone know the specific voltage that the OI on the control board takes? We have forgotten ours and we cannot get back into the school and were going to buy one at Radio Shack or somewhere, but there is no listed voltage on the OI or on the Innovation FIRST website. Any exact answers would be appreciated. Cyber Blue thanks you.
I think our 2004 OI on our OCCRA robot is wired to a 30 amp fuse, it runs pretty fine to me.
I suggest to stick with somewhere around a 30 amp fuse.
9v DC
Center positive on the connector
Jason,
The power supply crosses to a 9 volt DC 1.5 amp power supply but there is no way I can tell you polarity right now. IFI is adamant about using only their power supply, though.
Even though it runs flawlessly with 12 V, for several years and on several OIs, and with no apparent damage or even excessive heat generation.
I think IFI’s main concern with the power supply is more related to the current, as the great majority of cheap 9 V power supplies doesn’t even come close to the 1500 mA required for operation, and less current could cause erratic operation of the OI.
Originally taken from a post by dlavery
This is the correct Radio Shack unit (that we currently use)
In the store, they will have a hanging thing with a whole bunch (about 50) of different plugs. Make sure to take the OI with you to find a plug that fits and plug it in and make sure it lights up in the store because there are probably about 3 or 4 that seem like they might fit.
Make sure your 9v DC P/S is rated at 1500mA. We had a problem when we lost the OI’s supplied AC adaptor, and a team member picked up any random Power supply thinking it was the right one. Well after a few hours of checking the bot for loose connections or broken pins on the RC and radio we figured out that the power supply was not giving enough current to run the OI. DUH!
Now, if you’re willing to “risk” your OI using it at 12 V, why don’t you get a small battery and go portable? 
That’s what we do here, those batteries last about two hours and we paid 15-20 dollars each. Get one for each robot and you’re all set for presentations!