10/10/2012

How to build a robot #6 - battery pack hack, de-spaghettiizing, and another test run



The first order of business in this session is to correct my power problems.  In the last filming I was using the 6VDC from the battery pack to drive the motors and to provide 5VDC to the Arduino Nano.  I was wrong on both counts!  The motors are rated for 3VDC and the Nano really either needs a regulated 5 volt power source, or a 7-12 volt input to VIN so it can regulate the power itself.

The first fix was to NOT power the Arduino from the battery pack.  I used a 9 volt battery instead, feeding into VIN.  The second fix was two-fold.  First, I used a piece of wire to delete one cell from the 4 cell battery pack.  I also used 1.3 volt  rechargeable batteries  instead of 1.5 volt alkalines.  So I went from giving the motors 6 volts to giving the motors 3.9 volts.  If I had kept feeding them 6 volts, they may have had an hour left in them if I was lucky.

The last issue to resolve for this session was to de-spaghettify the wiring on the first level breadboard.  I'm going to have a lot more wires connected to the breadboard, and it's already a mess.  Pre-made jumper wires are nice for quick connections, but they quickly turn into a real problem.  They are too long, so you end up with a big pile of spaghetti.  It's hard to tell where they are going and it's real easy to accidentally pull one out.

The fix is to simply cut proper length wires that can lay down flat.  It's tedious, but the end result is worth it.  I'm going to have enough problems to troubleshoot in this robot without having to worry about loose jumper wire spaghetti.

During this video I realized a couple of items that need to be taken care of.
#1 - I want a power button on the exterior of the robot.
#2 - I need a way to secure the 9 volt battery