46 June 2014
■ FIGURE 9. The 16-pin RA SIP header. Just mount this
header along the bottom edge.
■ FIGURE 11. Sixteen .1 µF capacitors. These go in
the upper set of holes. Now, your tester is complete!
(Oh, so you're wondering about the extra hole?)
■ FIGURE 12. The extra hole was for an optional grounding
wire. Originally, the design required a grounded bus. However,
the state of all the other lines during the tests acts as an
effective ground, making the wire unnecessary.
Assembly Time ... Again!
This next board is much smaller, requiring only three
different parts. Figures 8A and 8B show the front and
back of the PCB. The layout is intentionally simplistic.
Again, ExpressPCB came to the rescue with fast boards.
Of course, as small as this design is, I managed to get
12 modules out of one order of the mini-boards by
panelizing the design.
■ FIGURE 8A. PCB front. ■ FIGURE 8B. PCB back.
■ FIGURE 10. Sixteen 10K resistors. These go in the lower
set of holes.