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When you're done, solder the right optoisolator in place using the same procedure. Inspect the
joints carefully... the optoisolators have short stubby leads, and it's relatively easy to have the
solder on the pads miss the leads if you don't use enough solder.
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Mount the 3.3V Voltage Regulator
Locate the large pad and the three small pads for the voltage regulator. Heat up the large pad
with your soldering iron and melt a small amount of solder on the large pad, just enough to
cover it. Place the voltage regulator IC in place, and hold it down, then heat up the large pad
on the voltage regulator until the solder starts to flow. Hold your soldering iron on the pad for
another 5 seconds, then remove it and wait at least 10 seconds.
One by one, solder the three small three small leads to the pads, using enough solder to cover
the pad and get a good "tenting" on the leads without creating solder "blobs". Wait at least 30
seconds between each pad to prevent the chip from overheating.
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Mount the 2.2K resistor
Locate the 2.2K resistor (marked "222") next to the regulator. Solder it in place.
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