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"one-way switches" in this manner to protect internal circuitry. In our case
we use the diode "double duty", because if you use an AC wall adapter this
diode will act as a half wave rectifier to provide a DC voltage to the input of
the voltage regulator IC.
6. Identify C4, the 1000 uF electrolytic capacitor (cylindrical component and
marked 1000 uF). Electrolytic capacitors are polarized with a (+) and (-)
lead and must be installed in the correct orientation. Ordinarily only the
negative side is marked on the capacitor body with a dark band and the (-)
sign clearly shown, while the PC boards will usually show the (+) hole
location. Normally the part also has one lead that is shorter than the other
and this also corresponds to the negative lead. Use care to ensure proper
polarity. See the parts diagram for proper placement. The capacitor should
fit snugly down to the PC board. Save those long leads that you trim off to
fashion jumper connections later in the assembly.
7. Identify VR1, the 78L05 voltage regulator IC (the three leaded
component labeled 78L05). This component is in a TO-92 package, and
again proper orientation is required for correct operation. The component
should be mounted so that the "flat" side of the part mounts facing the
previously installed capacitor. Use caution not to stress the leads when
inserting or soldering. Use the parts layout diagram as a guide for proper
orientation. This part works by "smoothing" out any junk that may reside on
the non-regulated side of the part. It also allows you to run this kit from a
wide range of supply voltages on the input, while it keeps the output to 5V.
8. Install C5, the 10 uF electrolytic capacitor (marked 10 uF). Remember to
observe polarity with those electrolytic capacitors! Check the parts
placement diagram for correct orientation.
Recheck your work up until now, trimming those component leads as you go.
Next we will work on the "feedback" portion of the circuit that lets us know we
are receiving and executing commands from the remote control unit, both using
an audible beep and light emitting diode.
9. Install D2 on the other side of
the board (the Green LED). This
LED will blink when the IR
detector sees data to let you know that an IR signal has been seen. D2 only
works in one direction. After all it is a diode, so have a look at the diagram.
The long lead indicates the Anode, the shorter is the Cathode, as well as
the larger fat base that you may see inside of the LED case. This Cathode
is also indicated by the flat side of the LED if you look at it end-on; you
really can't miss on this one. If you look at the board we have a flat side
indicated on the silk screen. Orient the LED so it's flat side is the same. Do
NOT mount the LED flush to the board, but mount it as high as possible, or
about 1 1/4" off of the board. The LED will eventually be bent over to peek
out of the front of a case.
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