jhphelan
03-20-2007, 08:54 AM
Tired of batteries running out during prolonged testing & debugging? Me too. Philo produced an elegant solution http://www.philohome.com/nxtsupply/nxtsupply.htm. My solution is less elegant but quick and effective. It doesn't have a fuse or voltage controller but relies on a good quality power supply. I've not had any problems with my Radio Shack supply so far, but for best performance I recommend including an in-line 3A fuse and a 9v voltage controller as per Philo. Attach a power jack that matches the plug from the power supply to a 9v battery connector. Use REVERSE polarity as the connector is representing the battery. Take another 9v battery connector and attach it to two AA 'batteries' made from wooden dowels. Each dowel is 1/2" x 1 7/8" with a round head screw for the positive terminal on one dowel and a pan or flat head for the negative terminal on the other. I drilled a hole in the side of each dowel for the wire which joins the hole for the screw. The terminal screws clamp the wire in place. I identified the positive 'battery' with red tape and the negative battery with black tape. I also cut off the tab from the lid of the battery holder to permit an exit for the wires. Identify the positive and negative contacts in the battery holder. They will be the only ones that do not span 2 batteries. Insert the positive 'battery' into the positive terminal slot with the screw end positive. Insert the negative 'battery' into the opposite slot with the screw end negative. Double-check your polarity all the way from the power supply to the terminals. Snap the battery connectors together. Plug the power supply into the wall. Check the voltage at 9v. Lastly plug the supply into the jack. You should hear the NXT power up.