The Mysterious Magic Box — Part 2
and sandwiched between. Use a
5/16” spacer and a #4 by 3/4” wood
screw at each corner. Attach wires to
the terminal block and hinge screws if
you have not already done so.
Insert the optical fiber into the
heat shrink at one end and shrink the
tubing. You can easily shrink it with a
hair dryer, but do not touch it with a soldering iron! This can damage the optical
fiber. Use another piece of shrink tubing
around the tilt sensor so that it does not
inadvertently short to anything metallic.
Cut a small piece of the end with a
razor knife at 90 degrees to get a clean
end for maximum light output. Insert the
heat-shrunk end through the wooden
support on the side of the box
with the corresponding hole.
There will be a 1/4” or 3/8”
sunken recess about 0.05
inches deep on the side which
faces the interior of the box.
Insert the optical fiber and heat
shrink through the molded
Nylon insulator so that the
“washer” side is nearest and
flush with the end of the optical
fiber. Insert the molded Nylon
insulator, with the fiber running
through it into the 9/64” hole in
the wooden support (see Figure
19). Insert the wooden supports
into the box. This should line up
the optical fiber with the hole in
the box’s side.
Attach the terminal block
to the PCB assembly. For the six
pawn version, attach the optical
fiber to the PCB. Insert the 9
VDC battery into its holder.
Install this assembly with the
PCB component side down and ❑ T
the battery holder to the right.
■ We wish to thank Stephanie Fennelly
of Allegro Microsystems for supplying
us numerous pieces of high quality line
art and for having a member of the
Allegro technical staff read this article to
ensure its technical accuracy.
Test the assembly by installing the
six pawns into their respective holes.
You should observe seven pulses at
the end of the optical fiber through
the pinhole and feel the corresponding tingles when you touch the
hinge. You should observe one long
and six short pulse durations.
We hope you enjoy the construc-
■ FIGURE 19. Inserting the nylon
extended shaft shoulder washer into
the cradle’s right side member.
tion of the Magic Box and are able to
spend many hours mystifying and
bewildering family and friends. NV
Passives (all resistors are 1/4 watt 5% unless stated otherwise)
❑ R1, R4, R7, R11, R12,
R15, R18, R19, R22-R25
❑ R8, R13
❑ R10, R20, R21
❑ C2-C8, C13, C14
❑ C9-C12, C15, C16
100K rate control pot (various suppliers)
10K amplitude control pot (various suppliers)
6. 8 µF tantalum polarized capacitor
0.1 µF capacitor 0.25” spacing (various suppliers)
0.01 or 0.02 µF capacitor 0.2 or 0.25” spacing (various suppliers)
❑ U2, U3
❑ U7, U15
❑ U5, U6
❑ U9, U10-U14
❑ LED 1
❑ Q1, Q2
A3214LUA SOT package (Digi-Key P/N A3214LUA-ND)
LEDXMTR blue LED or Industrial Fiber Optics P/N IF-E96
(Digi-Key P/N FB128-ND)
SPST tilt switch, metal case two-lead
(Electronix Express Rollerball P/N 1700TLRB)
2 VA CT transformer, like Tamura SB2812-1204
(Digi-Key P/N MT7249-ND)
2 pin .197” (5mm) Euro terminal block (Jameco P/N 164793)
■ FIGURE 18. Installing the
wires onto the terminal block.
❑ Two #6 stud ring terminals,
22-16 AWG (Jameco P/N 103684)
❑ 9 VDC battery holder (Digi-Key P/N BH9V-PC-ND)
❑ Six or four pawns with six or four magnets and felt self adhesive pads
❑ Metallic hardware
❑ 19 pieces of plastic hardware
For the six pawn enhanced version, delete R18-R21. For the basic four pawn version, delete
C13-C16, R22-R25, and U13-U15. Send a personal check, cashier's check, or money order.
International orders also accepted. Address it to Vaughn Martin, Zonemasters, 106 Shadowood
Drive, Warner Robins, GA 31088. The price of the six pawn kit is $39.95 plus $5 shipping and the
four pawn kit is $33.50 plus $5 shipping. The wooden box is $12 postage paid and the PC board
is $12.50 postage paid; www.zonemasterskits.com.
May 2007 55