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We use three AAA batteries in this project to supply 4.5 volts. If we used

a four-battery pack as we do in other chapters, the supply voltage would

be about 6 volts, above the maximum supply voltage allowed for the

SpeakJet IC.

SpeakJet sound synthesizer IC1

You can find a list of distributors on the manufacturer’s Web site, http://www.

speakjet.com.

LM386N-1 amplifier IC3

Of the many versions of the LM386 amplifier, we chose the LM386N-1

because it works with the supply voltage of 4.5 volts used by this circuit.

MAX232 driver/receiver IC2

SPST (single-pole, single-throw) slide switch, used as the on/off switch

830-contact breadboard

Eight 2-pin terminal blocks

Knob (for potentiometer)

8 ohm, 1 watt speaker

Three tactile switches (S1, S2, S3)

Many of these tactical switches are very small; for example, a 6 mm × 6

mm switch is less than^1 ⁄ 4 " square. We bought 12 mm ×12 mm switches

(part #TS6424T2602AC) made by Mountain Switch at Mouser (www.

mouser.com).

Enclosure

We used Radio Shack part #270-10807.

Six phono plugs

Six phono jacks

DB9 female connector

There are about as many DB9 connecters out there as there are fish in

the sea. We used RadioShack part #276-1538.

DB9 serial port cable

Four^1 ⁄ 2 " 6-32 flathead screws

Four 6-32 nuts

An assortment of different lengths of prestripped, short 22 AWG wire

146 Part II: Sounding Off!