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In this part... T he chapters in this part all deal with things that vibrate in some fashion, from sound waves in the air to a f ...

Chapter 12 Chapter 12: A Handy-Dandy Metal Detector ............................................................... In This Chap ...

Here are the types of activities you’ll be doing to build the metal detector. You will Build a pretty simple electronic circuit ...

Here’s a list of the schematic elements: L1is a coil (also called an inductor) wired in parallel to capacitor C1; the combinati ...

adjusting the value of the variable resistor when the coil is not near any metal objects. R5 is a resistor connected between th ...

120 ohm resistor (R5) Two 0.0047 microfarad ceramic capacitors (C1, C3) One 2N3904 transistor (Q1) One T-1^3 ⁄ 4 LED (LED1) ...

Taking Things Step by Step......................................................................... Although the circuit is simp ...

Base pin Emitter pin Collector pin Figure 12-5: The 2N3904 pinout. Coil TB IC 1 Potentiometer TB Battery TB Q1 LED TB Figure 12- ...

Insert wires to connect the battery terminal block and the transistor emitter pin to the ground bus. Then insert a wire between ...

Insert wires to connect the IC and discrete components, terminal block for the coil (L1), terminal block for the potentiometer ...

Insert two 0.0047 microfarad capacitors (C1 and C2), two 247 ohm resistors (R3 and R5), one 1 kohm resistor (R1), and one 120 o ...

Building the box to house the circuit .............................................. The box that houses the circuit needs holes ...

See Chapter 4 for more information about choosing drill bit sizes for par- ticular components and other advice about how to cust ...

Solder an 8" wire to the center potentiometer lug and another 8" wire to the left potentiometer lug, as shown in Figure 12-11. ...

Insert the wires from the LED, potentiometer, on/off switch, and bat- tery pack to the terminal blocks on the breadboard, as sh ...

Glue an 8", 1"-diameter PVC pipe into one end of a 45°-angle PVC pipe fitting, facing up. (See the upcoming Figure 12-13.) Glue ...

Solder 12" wires to each of the two inductor leads, as shown in Figure 12-14. Slip a 1" segment of heat shrink tubing over each ...

Cut the wires to allow three inches to extend from the^3 ⁄ 8 " hole in the pipe and attach each wire to a right-angle phono plu ...

You can use either a plug that requires soldering to the wire or one that uses a screw to secure the wire, as we have here. Pre ...

Trying It Out.................................................................................................. You probably hav ...