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Electricity and Basic Electronics
Project 12-1: Magnetizer-
Demagnetizer
Here is a project that will allow you to
magnetize or demagnetize small tools. There
are times when a magnetized screwdriver can
be a big help in tight quarters. There are other
times when a magnetized tool will hinder an
assembling operation.
See the two views of the magnetizer-
demagnetizer pictured. Then, study the following
schematic.
Gather the necessary parts and assemble
the project according to the schematic and the
construction procedure that follows.
Procedure
1. Saw off both ends of ten 20-penny nails,
leaving them approximately 2 1/4″ long.
2. Spray each nail with a thin coating of
lacquer.
3. When dry, wrap the nails with adhesive
tape to form the core of the inductor.
4. Cut two circles of cardboard and put one
at each end of the core, leaving about 1″ of
space between the cardboard circles.
5. Wrap layers of No. 36 magnet wire around
the core, totaling about 4500 turns.
6. Before cutting the wire, scrape the enamel
to bare a spot for attaching an ohmmeter
lead. Bare the starting end of the coil wire
and connect the other ohmmeter lead to it.
The resistance should be between 425 Ω
Item
Handmade inductor
Electrolytic capacitor, 20 μF, 200 V
Silicon diode, 400 mA or higher, 300 V
Wirewound resistor, 200 Ω, 5 W
Momentary contact push-button switch
DPDT toggle switch
Lamp cord, 110 V
Plastic box and cover, 6″ × 3″ × 2″
Epoxy, tape, solder, and soldering iron
No.
1
1
1
1
1
1
1
1
and 450 Ω. If the resistance is lower, add
turns of wire to the coil and recheck the
resistance value.
7. Cut a hole in the cover just large enough
for one end of the core to protrude about
1/4″ through the cover.
(Project by Robert Wong)
Magnetizer
Demagnetizer
D1
S1
S2
C1
C
R1
L1
110 V
AC
−
+