Lego Minsdstorms NXT AC adapter mod

Hi all,

I have created a Lego Mindstorms trap to see which cat was leaving deposits in my robot workshop.

We used the Ultrasonic sensor and a motor to wind up a string to close the door, all nice and simple and I now have the culprit :)

During construction, we had to make it work from an AC adapter rather than batteries as it was to be left on all night, so we made a little adapter. We used inspiration from another design I found on the web at

http://www.philohome.com/nxtsupply/nxtsupply.htm

To build this Instructable you will need

Scrap piece of copper clad pcb board
Soldering iron and solder
8-9v, min 1.5 amp power supply
AA battery connectors form an old toy
Scrap connector pins
Hot melt glue
Craft knife
Mulitmeter
About an hour of your time

Trouble with the original one was that you needed to remove the battery cover and leave the board exposed which looks a little tatty. Although my version still looks a bit tatty, at least its hidden by the original battery cover.
 

Step 1 Create the slide in board

A better way would be to create a slide-in board that would allow the battery cover to be replaced back over it again. to cover up and protect the board.

**You need to be compentent with a soldering iron and know how to use a meter to check voltage and polarity. I take no responsibility for your problems, you build this at your own risk. **

I had some copper-clad PCB board around and cut a section 38mm x 85 mm, I also scavenged through some old broken battery operated toys to retrieve an AA spring and plate which could be soldered to the copper board to mate with the two main contacts of the controllers battery compartment.

These soldered on very easily. Once I was happy with the position, I cut the copper around them with a knife to ensure they were electrically isolated from the rest of the board.

I then took some old connector pins, anything will do, and soldered them on to the board so they aligned with the original spings along the battery bay and gave the board something to push against to keep it all aligned and centralised. They are not connected to anything, purely to keep it all in place.