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b. The LED is installed on the PCB in the spot marked LED. The LED, being a diode, is polarized
and must be installed in the correct orientation. If you get it backwards, the light won’t work.
The long lead goes into the hole with the square pad. Make sure the standoff is standing
straight up. Bend the leads out on the bottom; flip the board over and solder and clip the
leads (83).
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83
c. If you look closely at the body of the LED, you will notice that there is a flat edge on the side
closest to the back edge of the PCB. Make sure the LED’s flat side is parallel with the back
edge of the PCB. Twist the LED, if necessary, to align these edges. This prevents the leads
twisting inside the standoff and possibly shorting out to one another.
84
17. Battery Holder (BT1): Before we install the battery holder we need to slightly modify the screw
holes to allow them to better accept the screws.
a. Use the tip of your X-Acto knife to gently flare out the ends of the screw holes just a little
bit (85). To pre-thread the holes, use a #2 Phillips screw driver to drive an M3x6 machine
screw (part #FA-60-37) into each hole. Make sure the screws go in straight (86). Remove the
screws.
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86
