Justin Ratliff's ping robot article

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Once I knew what I needed to focus on I could design the board. Figure 2 shows
the J2 schematic and figure 3 shows the PCB artwork as laid out using free
software from www.expresspcb.com Prices for boards are very reasonable. One
note of caution, double check the hole spacing and size before you place an order.
With all the options it’s easy to choose a wrong size or settings. It’s a great program
and service and I highly recommend them for anyone.
Figure 2.