Hello All, I'm a minidisk user for several years and new to the forums. I have been using an old MZ-M505 Net MD walkman on my desk at work for several years. I want to share a tip for making a super long-lasting external battery pack. Forgive me if this has been covered.. I didn't see this in previous topics of the technical tips forum. This pack works for portable players having a 3VDC DC IN jack (normally for the charger). This pack has been powering my player for 10 months, avg about 3 hrs per workday (M-F), one the SAME set of batteries. From Radio shack, purchase: 2 D cell plastic battery holder Male coaxial power plug that fits the DC IN jack of your player. 2 D-size alkaline batteries One AA alkaline battery (for your player) This holder is designed to connect the batteries in series, creating a portable 3V DC source. Wire up the coaxial plug to the holder with a suitable length of wire, taking care to route the red + lead to the center hole of the plug, as illustrated on the side of your player. Check it with a meter! Install the batteries, plug it up, and enjoy an absolutely amazingly l o n g playback time! Happy Building! Nylo