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Detail of the power stages.
I used TO-220 N-channel MOSFET transistors but to prevent the return ground from being broken up via through holes the transistor legs were cut short and soldered to the top layer pad.
Also, the drain tab is soldered to a large thermal pad on the top layer with no through hole for the mounting bolt. Therefore all the transistors have their drain tabs soldered to the top layer.
N-Channel MOSFETS were used due to their lower on resistance. In the case of these devices the quoted on resistance is 9 mOhms each.
As the MOSFETs are N-Channel they require the gate voltage to be higher than the source to turn on. But the transistors are used to switch the high side, 100V input from the solar panels. Therefore a charge pump arrangement was designed to pump the gate to ~8V above the source (10V less 2x diode drops).
On the right hand side of the board is the 100V to 10V flyback PSU. A local 5V linear regulator supplies the current monitor devices and feeds 5V up to the MCU controller to power the Arduino and logic circuitry.
We were trying to build a very simple robot able move towards the light.
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the workshop's wiki report:
I bough an new Arduino Duemilanove that come with an extra resistor. This resistor need to be removed to Arduino serial works
Video CUT SHORT!!! Flickr only shows the first 1:30, dang...
Please watch the full video here: www.youtube.com/watch?v=OTe030AWESE