We recently did just that. I needed to do some measurements at 130KV potential and after looking at some solutions, we decided to use a die grinder attached to a 3 phase motor similar to the ones used for driving hard drives and such. We also tried a brushed DC motor but that was not so good. We manage to get around 14V DC (after rectification) @ 1A, and it worked very well. But like some pointed out lubrication is an issue, not only because it requires it but also this tools have no return pipe hence you can end up with everything covered in oil. The other issue we found was vibration. As this was a temporary setup for us, the motor to grinder coupling was made directly, After running it for 4 hours continuously the system stopped. At first we tough that the grinder seized but actually it was the motor that do to the vibration damaged one of the windings. Most of all what we found, specially when we first tried the system with the DC brushed motor, is that the choice and combination of air motor and motor( as a Generator) is very important. Specially the RPM required/supplied and torque. Best Regards Luis -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of William "Chops" Westfield Sent: 03 November 2008 03:10 To: Microcontroller discussion list - Public. Subject: Re: [EE] Compressed air electric generator? On Nov 2, 2008, at 6:05 PM, Enki wrote: > I'm looking for a generator. A very small one, 10-15W will do the job. I'm not experienced in the area, but 10-15W sounds like a pretty substantial generator to me. For comparison, bicycle generators look to be about 6W... You may be stuck with some sort of air-powered motor (die grinder?) connected to a motor run "backward." BillW -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist