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120 ohm resistor (R5)

Two 0.0047 microfarad ceramic capacitors (C1, C3)

One 2N3904 transistor (Q1)

One T-1^3 ⁄ 4 LED (LED1)

LED panel-mount socket, T-1^3 ⁄ 4

TDA0161 proximity detector (IC1)

Battery pack for 4 AA batteries

680 picofarad bobbin-type inductor (L1)

We used C&D Technologies part #1468420C that we picked up at Mouser

(www.mouser.com).

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

switch

400-pin breadboard

Four 2-pin terminal blocks

Knob (for the potentiometer)

Two phono jacks

Two right-angle phono plugs

We used right-angle plugs to avoid having a loop of wire coming out of

the box. You can also use banana plugs and jacks.

Enclosure

We used a plastic box, RadioShack part #270-1806.

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

Two PVC 45° joints with 1" slip fitting on both ends (one male and one

female)

PVC 1" end cap with 1" female slip fitting

1" diameter PVC pipe (referred to as schedule 40 pipe), 1' in length

1" clamp to attach the enclosure to the pipe

Two^1 ⁄ 2 " 8-32 panhead screws

Two 8-32 nuts

Chapter 12: A Handy-Dandy Metal Detector 285