How to Make a 1 Ohm to 100 Megaohm Resistance Decade Box
Be sure that you have all of the things needed.
Step-by-Step Guide
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Step 1: Be sure that you have all of the things needed.
Eight thumbwheel decade switches (shown in the image).
Make sure not to buy BCD-encoded decade switches.
These have to be 10-way decade switches with 11 connectors per switch.
Unlike BCD-switches which have only 5 connectors.
You can buy these switches from a surplus store, but they are available at about $1-3/switch.
Resistor assortment containing at least nine values of 1, 10, 100, 1000, 10k, 100k, 1M, 10M ohm resistors.
In this example, 3 W resistors are used, but 1/4 W or even 1/10 W will be enough as well.
Be aware, that using smaller wattage or surface mount resistors will limit the current and voltage.
The 1/4 W resistors are easy to solder due to their small size.
The 3W resistor set can be bought from eBay for about $12.
Binding posts.
In this project, 3
- way audio binding posts are used.
They were installed in a house which had wall audio wiring.
The wall plates with the binding posts were removed and used here.
A case to hold the switches with resistors and the binding posts.
It can be built from wood or any other material.
Tools.
Wire, wire strippers, wire cutters, soldering iron, solder, desoldering wick.
Needlenose pliers, hemostat or crocodile clips.
Drill and drill bits.
Patience.
Soldering 72 resistors with about 150 solder joints take some time.
Detailed Guide
Eight thumbwheel decade switches (shown in the image).
Make sure not to buy BCD-encoded decade switches.
These have to be 10-way decade switches with 11 connectors per switch.
Unlike BCD-switches which have only 5 connectors.
You can buy these switches from a surplus store, but they are available at about $1-3/switch.
Resistor assortment containing at least nine values of 1, 10, 100, 1000, 10k, 100k, 1M, 10M ohm resistors.
In this example, 3 W resistors are used, but 1/4 W or even 1/10 W will be enough as well.
Be aware, that using smaller wattage or surface mount resistors will limit the current and voltage.
The 1/4 W resistors are easy to solder due to their small size.
The 3W resistor set can be bought from eBay for about $12.
Binding posts.
In this project, 3
- way audio binding posts are used.
They were installed in a house which had wall audio wiring.
The wall plates with the binding posts were removed and used here.
A case to hold the switches with resistors and the binding posts.
It can be built from wood or any other material.
Tools.
Wire, wire strippers, wire cutters, soldering iron, solder, desoldering wick.
Needlenose pliers, hemostat or crocodile clips.
Drill and drill bits.
Patience.
Soldering 72 resistors with about 150 solder joints take some time.
About the Author
Brian Gray
Creates helpful guides on hobbies to inspire and educate readers.
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