Wednesday, June 5, 2013

Dual Motor Cape Version 4 is in!!


I'm using the Silhouette Cameo Stencil cutting technique I found from http://www.idleloop.com/robotics/stencil/index.php.  The results were good enough to use:
Minor variations I found was that I had to set the physical cutter depth to 3 instead of 1 as indicated in Cathy Saxon's article.

Populating the board (except for missing J4, still in transit from Mouser):

One of the things you'll notice that I've changed is the motor and power connectors.  I've using Molex Microfit connectors http://www.molex.com/molex/products/family?key=microfit_30&channel=products&chanName=family&pageTitle=Introduction, instead of the screw terminals.  The reason for the change is that I felt that using the screw terminals might be unreliable when using this board on a mobile robot.  The only downside is that the Microfit connectors are rated at 5A max.  I think I will have to leave it at that spec when I sell the boards (although you could always solder wires directly to the board to get a higher current -- the ST Micro HBridge chips are rated for up to 30A if you add a few heat sinks in).  I'll probably keep the spec at 5A continuous, and 10A peak (violating the Microfit spec a bit -- they do spec the two circuit connector at 7A, but I want a little leeway).