Building an amplifier circuit
The first step in building a parabolic microphone is
to tackle the circuit that forms its electronic brains. Here are the
steps involved:
1. Place LM386N-1 (IC2) and
five terminal blocks (TB) on the breadboard, as shown in Figure 6-5.
The five terminal blocks shown in this figure will be used to connect
two wires each to various components in the circuit. The wires from
these five terminal blocks will go to the battery pack, the on/off
switch, the microphone, the speaker, and the potentiometer.
2. Insert wires to connect the IC and the terminal
blocks to the ground bus and insert a wire between the two ground buses
to connect them, as shown in Figure 6-6.
Six shorter wires connect components to ground bus; the long wire on the
right connects the two ground buses.
3. Insert wires to connect the
IC and the terminal blocks to +V, and a wire between the two +V buses to
connect them, as shown in Figure 6-7.
4. Insert wires to connect the ICs, terminal block
for the microphone cartridge, terminal blocks for the potentiometer
(R2), terminal block for the headphone jack, and discrete components, as
shown in Figure 6-8.
4. Insert wires to connect the ICs, terminal block
for the microphone cartridge, terminal blocks for the potentiometer
(R2), terminal block for the headphone jack, and discrete components, as
shown in Figure 6-8.
5. Insert the 0.047 microfarad capacitor (C5), two 10
microfarad capacitors (C2 and C3), one 100 microfarad capacitor (C4),
one 0.1 microfarad capacitor (C1), one 5.6 kohm resistor (R1), and one
10 ohm resistor (R3) on the breadboard, as shown in Figure 6-9.
When inserting electrolytic capacitors, be sure to check the schematic
for where to insert the longer + lead. We discuss in
"Discovering
Schematic" how you can determine how short to clip the leads
of many of these components to make them fit neatly on the breadboard.
And you knew we were going to say it: Make sure you wear your safety
glasses when clipping leads!
