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A few months ago, I developed and open source the 4xMacropad, a $3 macropad made using CH552G. After seeing much of the feedback from the internet, I notice I can better utilize this chip to make a keyboard with more keys. That is why I am trying to make a numpad in order to use 100% potential of this particular chip.

There are lots of good looking mechanical numpad out there with cool designs. But most of them falls into the 40 - 50 USD range (for DIY kits). That is why when I am deciding this numpad, my goal is to make it as cheap as possible, while maintain the good features from the previous builds:

- Arduino Programmable
- Cheap and easy to make
- Little to no change in BOM list

While improving some designs that was most commented agaist
- Swap out the mini USB port

After a few weeks of trial and error, I finally get a numpad made with the identical BOM list (actually this numpad has less SMT parts than the pervious 4xMacropad build) and successfully make it cost under $10 USD.
In this instructable, I will quickly walk you through my process of designing this numpad and how you can make yours for $8 USD as well (Disclaimer: Shipping not included)


Circuit Related Items

- 0805 LED x 2 (2 different color of your choice)
- 0805 0.1uF x 2
- 0805 10kΩ x 7
- Micro-USB port x 1
- SMT Button
- SOP-16 CH552G x 1

The parts that related to the circuitary add up to less than 2.2 USD

Switches Related Items

- Cherry MX switches x 17 (or 20 if you are using macro-numpad layout)
- Key-caps x 17 (or 20)

And these are where the remaining costs are spent”

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