![](https://blog.hegars.com/wp-content/uploads/2021/08/image-2.png)
https://en.wikipedia.org/wiki/Binary_decoder
Use in a switch to detect and use the off position
![](https://cdn.ready-market.com/106/5213db54//Templates/pic/T8013.jpg?v=47dd61ce)
![Toggle Switches T8013](https://www.salecom.com/Templates/pic/T8013-PD.jpg)
Chips
SN7404 Hex Invertor
SN7414
SN7408 Quad AND gate
or SN74138 3-Line To 8-Line Decoders/Demultiplexers
Test Platform
Using pure logic
![](https://blog.hegars.com/wp-content/uploads/2021/08/image-11-1024x769.png)
![](https://blog.hegars.com/wp-content/uploads/2021/08/image-6-1024x667.png)
![](https://blog.hegars.com/wp-content/uploads/2021/08/image-10-666x1024.png)
Using a 74138 decoder per switch
![](https://blog.hegars.com/wp-content/uploads/2021/08/image-13-1024x548.png)
adding pull down to the switches