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9. Install C7, a 0.1uF ceramic capacitor (marked 104). Disc capacitors are
not polarized, so either direction is alright.
10. Install R13, 10 ohm resistor (brown-black-black). Resistors are not
polarized; they may mount in either direction.
11. Identify and install the mini speaker. SP1 (small round object with two
leads protruding). You may notice a "+" sign adjacent to where the leads
attach, but for our application polarity is not a concern. Mount it adjacent
to R13, as shown in the parts placement diagram.
12. Identify the small signal transistor Q5 (three leads marked 3904).
Notice that there is a "flat" side of the component. Install transistor Q5,
being sure to mount the flat side as shown in the parts diagram. This
transistor is the driver for the mini speaker and it provides enough current
to make the speaker "beep".
13. Install R5, a 220 ohm resistor (red-red-brown).
14. Install R20, 1K ohm resistor (brown-black-red).
15. Install R12, 10K ohm resistor (brown-black-orange).
That's getting the hang of it! Believe it or not you're already about halfway
through the assembly of your kit. Recheck your solder connections and touch
up any less than perfect ones. Watch out for any solder bridges on the solder
connections.
Lets get to work on that microcontroller. We will start with the connections that
"talk" to the IC and work our way over to the chip.
16. Identify the jumper block headers (or strip of headers) included with
your kit. If not already done, snap the pins off in pairs so that you have five
sets of two pins. These will install on the circuit board with the longer ends
facing upward to provide connection points to configure the micro-
controller IC. Use caution soldering these as the heat from the tip of your
iron will quickly travel down the metal post, and can give you a nasty burn
if your are holding it in place with an extra finger. Install headers in the
J13, J12, J11, J10 and J9 position.
17. Install resistors R7, R8, R9, R10, and R11, all 10K ohm (brown black-
orange) into their respective positions. These resistors are referred to as
"pull ups", as they set the voltage at the associated pins of the
microcontroller to +5 volts, whereas if the previously installed header is
shorted, the DC value on the pin becomes a low, or logic zero. They "pull"
the electric potential on the pins "up" to the +5 volt level; that's where the
name comes from.
18. Install the socket for U1, the Motorola 68HRC908 20 pin micro
controller IC. It doesn't matter which way you install the socket but it
definitely matters which way you place the IC in the socket. Don't be afraid
ICI1 Page 14
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