Decade Resistance Box Hookup Guide
Byron J. Introduction
A decade box is a tool that contains resistors of many values accessed via mechanical switches. Adjust the knobs to output any of the discrete resistances offered by the box.
They are known as decade boxes because they have controls that correspond to the digits in a decimal number - a control for the tens position, a control for the hundreds position, and so on.
Traditional decade boxes looked like something out of Dr. Frankenstein's lab - large wooden enclosures, with engraved front panels and big Bakelite knobs. They were available in three main types - resistance, capacitance and inductance. This kit is for a decade resistance box. It allows you to quickly and accurately dial in a specific resistance value between 0 and 999,990 Ω, in 10 Ω increments..
In this hookup guide, we'll first assemble the decade box, then explore its application as a design aid and a test instrument.
Necessary Tools
- Soldering Iron
- Lead-based or Lead-free solder
- Diagonal or Flush cutters
Additional Tools and Supplies
- Red or black knobs are highly recommended - the rotary switches are very hard to turn without knobs!
- A small set of pliers
- Small Philips Screwdriver
- A few inches of solid core hookup wire.
- Safety Glasses
- Magnifying glass or Loupe
- PCB Vise or Third Hand
- Volt Meter
Optional Materials
The decade box can be assembled to fit in an enclosure or behind a front panel. In this tutorial, we'll build it into a cast aluminum enclosure.
If you want to build yours into an enclosure, you'll need the following.
- Aluminum enclosure
- Removable tape, such as painter's or gaffer's tape
- Center Punch and hammer
- A vise or clamps
- A drill press or hand drill
- A set of drill bits, or a step-drill
Suggested Reading
If you aren’t familiar with the following concepts, we recommend checking out these tutorials before continuing.
How to Solder: Through-Hole Soldering
Connector Basics
Voltage, Current, Resistance, and Ohm's Law
Resistors
Button and Switch Basics
Electric Power
How to Use a Multimeter
Also, it is recommended to check out this tutorial on enclosure modification:
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| Tutorial for Enclosure Modification |