October 2004

Monday 18^thOctober 2004

After a long break from robot- building due to holidays and other commitments I finally made a start on building a couple of current limiters for the motor drive circuits. There was no free space within the motor controller box itself to mount the limiter, but I found a void right next to the box just under the mounting bracket.

I was hoping to mount the current limiting MOSFETs on an aluminium "brick" similar in construction to the existing MOSFET final power stage. I was going to squeeze both left and right motor current limiters onto one brick and at the same time position the MOSFETs as close together as possible on the heatsink base. Both the heatsink and the bus bars were going to be made out of 6mm alluminium which I happen to have an abundance of.

Here are a few pictures of the current limiter in various stages of construction. It's a little hard to see clearly in the last photo, but the limiter fits quite nicely on the motor controller mounting brackets close to the power stage MOSFET bricks which simplified the wiring routing considerably.

Saturday 30^thOctober 2004

I tackled the problem of the hog's twisted flipper during the last week. During my last battle against Spawn Again, I was hurled into the air and landed on the front corner of the flipper. Most of the impact was absorbed by the aluminium flipper tip whose edge bent up. It was a simple case of unscrewing the tip and then wealding a club hammer at it to restore it near enough to its previous shape. The rest of the flipper was a different matter because of the triangulation nature of the struts. All of these had stretched slightly in the impact so it was virtually impossible to twist the flipper back to its original shape. In the end I hacksawed through several strutts and then ligned them all up again before welding them back together.