Assembling a Code-Practice Oscillator
It isn’t difficult to construct a code-practice oscillator. A complete oscillator that mounts on a small piece of wood is
shown in Figure A. Figure B shows all the parts for this project laid out ready for assembly. The circuit board for this project
can be ordered from FAR Circuits, 18 N. 640 Field Court, Dundee, IL 60118-9269. A complete parts kit, including circuit
board, is available from the Hoosier Lakes Amateur Radio Club, PO Box 981, Warsaw, IN 46581-0981
Contact these vendors for the latest pricing.
Please read all instructions carefully before mounting any parts. Check the parts-placement diagram for the location of
each part.



o Check each box as that part is installed and soldered.
Radio Shack Component Used in
Quantity Description Part Number Number Step Number
Capacitors
o 1 0.01-mF 272-131 C1 3
o 1 0.01-mF 272-131 C2 6
o 1 220-mF, 35-V electrolytic 272-1029 C3 5
Resistors
o 1 10-kilohm, 1/4 W (brown-black-orange stripes) 272-1335 R2 4
o 1 47-kilohm, 1/4 W (yellow-violet-orange stripes) 272-1342 R3 8
o 1 10-kilohm, 1/4 W (brown-black-orange stripes) 272-1335 R1 9
o 1 47-ohm, 1/4 W (yellow-violet-black stripes) 271-009 R5 11
Miscellaneous
o 1 100-kilohm potentiometer 271-284 R4 7
o 1 8-pin IC socket 276-1995 2
o 1 7555 CMOS Timer IC (or 555 Timer IC) 276-1718 U1 13
o 1 Loudspeaker — 2-inch, 8-ohm 40-245 LS1 11
o 1 Six to 10 inches of insulated wire, about 18 11
or 22 gauge
o 1 9-V battery connector 270-325 10
o 1 9-V battery 23-553 BT1 10
o 1 U-shaped battery holder 270-326 12
o 1 Brass rod, 2 inches long, approximately
18 gauge (about the diameter of a coat hanger).
Available at hobby shops.
o 4 1/4-inch spacers 64-3024 12
o 1 2´ 4 ´ 1/2-inch piece of wood for base 12
o 5 No. 6 wood screws, 3/4-inch long 12
o 2 No. 6 wood screws, 3/8-inch long 12
o 1 Five-lug tie point, used to mount speaker (optional) 274-688 11