To purchase a decade resistor box, please contact IET Labs.

If you need a really good decade box, click on the link above. IET Labs has a truly-excellent line of decade resistance, capacitance, and inductance boxes, "in the Genrad tradition".

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"Easiest Resistor Decade Box" Plans:

1 Ohm to 9,999,999 Ohms, in 1-Ohm Steps!

Parts consist of: two generic pre-etched and pre-drilled PCBs (printed circuit boards), 136 precision 1%, 1/2-Watt metal-film resistors (46 values), seven 1P10T rotary switches, seven knobs, two binding posts, wire, solder, drilled cast-aluminum or plastic case (7.5"x4.3"x2.4"), panel markings, and rubber feet.

TOLERANCES (maximums): total of 1% to 2%, or less, for 1 Ohms through 100K Ohms decades and 1Meg to 4 Meg Ohms values (one or two 1% series or multiple parallel resistors per value); total of 3% to 5% for 5Meg to 9Meg Ohms values (three to five 1% resistors per value).

This device was designed to use two generic-patterned, pre-made, pre-drilled circuit boards that are available from Radio Shack, and other places. All parts, including shipping, should total around $40. All parts are available from one of the following: Radio Shack stores (or, Jameco (, or Mouser ( The parts/suppliers list is farther below.

Main board:

Decade Resistor, Main Board

Ones-decade board:

Decade Resistor, Ones-Decade Board

Parts list:

(1) Circuit Board, 5 holes connected x 47 rows x 2 columns (Radio Shack 276-170)
(1) Circuit Board, 3 holes connected x 25 rows x 2 columns (Radio Shack 276-150)
(7) 1P10T Rotary Switches (Mouser 10YQ110 or other)
(7) Knobs (Jameco 136240, or other)
(2) Binding Posts (Jameco 77690 or other)
(1) Case, 7.5" x 4.3" x 2.4" aluminum or plastic (Jameco 11973 or 18905, or other)
(1) Wire, #22
(1) Solder
(4) Rubber Feet, Adhesive (Jameco 119618, or other)
(136) Resistors, 46 different values, 1%, 1/2-Watt, metal film ( @ $0.05 ea):

(25) 10 ohm
(3) 15 ohm
(1) 24 ohm
(7) 39 ohm
(1) 91 ohm

(1 ea) 100 ohm, 1K, 10K, 100K
(4 ea) 20 ohm, 200, 2K, 20K, 200K
(4 ea) 30 ohm, 300, 3K, 30K, 300K
(1 ea) 27 ohm, 270, 2.7K, 27K, 270K
(1 ea) 18 ohm, 180, 1.8K, 18K, 180K
(2 ea) 43 ohm, 430, 4.3K, 43K, 430K
(1 ea) 47 ohm, 470, 4.7K, 47K, 470K
(1 ea) 62 ohm, 620, 6.2K, 62K, 620K

(5) 1 Megohm
(20) 2 Megohm

For the panel markings, you can create them in a Paint-type program, and print them onto clear (or other) peel-and-stick labels. If using the aluminum case, you could also iron them on, using the toner-transfer method described in the "Making PCBs" link below.

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Background music: Three-Part Invention No. 8 in F major; by Bach, Johann Sebastian (1685-1750, Germany)

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