Electret microphone cartridge Trust us. We tried a lot of microphones to get this working just right (and save you the trouble). We finally decided on the Panasonic part #WM61A because of its very high sensitivity that allows it to pick up faint sounds. We found the WM61 at Digikey (www.digikey.com).

10 kohm potentiometer (R2)

10 ohm resistor (R3)

5.6 kohm resistor (R1)

0.1 microfarad ceramic capacitor (C1)

0.047 microfarad ceramic capacitor (C5)

10 microfarad electrolytic capacitors (C2, C3)

100 microfarad electrolytic capacitor (C4)

LM386N-1 amplifier IC1 Of the many versions of the LM386 amplifier, we chose the LM386N-1 because it is designed to work with the supply voltage of 6 volts required by this circuit.

Battery pack for 4 AA batteries

Edmund Scientific’s (www.edsci.com) 24"-diameter parabolic reflector, part #3053876

SPST toggle switch, used as the on/off switch

830-pin breadboard

Five 2-pin terminal blocks

Knobs for the potentiometer

Two phono jacks

Two right-angle phone plugs We use right-angle plugs to avoid having a loop of wire coming out of the box. (You can also use something called a banana plug and jack.)

Headphones We used a set of Philips HP170, but you can use any headphone you have available. Obviously, the better quality headphone you use, the better the sound quality.

Headphone jack We used a 1⁄4" jack. If your headphone plug is a different size, use the appropriate size jack or get an adaptor.