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which means that it must be installed in the proper orientation to work
correctly. You'll note that there's a stripe or band at one end of the part and
a band marked on the PC board silkscreen and Parts Layout Diagram.
Align the two bands and solder the diode in place.
9. Install C3, 470uF electrolytic capacitor (marked 470uF). Because this
is an electrolytic cap it has a polarity and must be installed correctly in order
to function. The other little quirky thing about electrolytic caps is that they
tend to explode when installed backwards. We're not trying to scare you,
just make you aware of the fact that care is needed when installing this part
and all the other electrolytic caps. You'll see a band or stripe down one
side of the part. This band typically has zeros or minus signs in it and
denotes the negative lead. If they have not been clipped off, one of the
leads should also be shorter than the other. The short lead is also the
negative. The PC board silkscreen has a '+' sign on it to show you where
the positive lead should be placed. With this in mind, place C3 with the
longer positive lead in the hole marked with the '+' sign and solder it in
place. Since it's a large part you'll want to have it flush to the PC board
before soldering. In fact, unless we tell you to do something different, make
sure that all of your parts are down as close to the PC board as possible.
It's good practice, especially in RF circuits, and your board will look neatly
and professionally done if you keep the parts low.
10. Next install C23, 10uF electrolytic cap, right next to C3 (marked 10uF).
As in the last step, follow the '+' sign for correct placement.
11. Install VR1, an LM1086CS-3.3 voltage regulator (3.3 volts). The body
of the part is meant to lay down on the silver square on the board and you'll
want to solder it to the board at that point. Simply melt some solder onto
the square, then bend the three leads of the part so that it can lay flat.
Place the leads through the board and solder them, then heat up the metal
tab on the regulator while pressing it down onto the silver square. This will
heat the solder underneath and secure the part to the board. It's not critical
so if you can't get it to solder, don't worry about it. It's just a bit of extra
mechanical strength and provides more of a heatsink, but we've yet to see
that part get warm so it's not going to affect your kit if you don't do it.
12. Install C4, another electrolytic capacitor (marked 10uF). Remember to
orient the part so that the positive lead is in the hole marked with a '+' sign.
OK, that was a good warm-up. Let's take a look at those solder joints to make
sure we're in good shape to move on. A good solder connection should be
shiny, smooth, and solid. No room for loose connections here! An old trick is to
wipe the hot tip of the iron across a damp sponge before soldering each
connection. This keeps the tip clean and spreads the heat faster for a solid
connection. If you haven't tried it, give it a shot and see how much easier it
goes.
BS2 • 12
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