USB Cherry MX Numpad

Almost a year ago, I bought my first mechanical keyboard. It's a Filco Ninja Majestouch-2 Tenkeyless (with Cherry MX Brown switches). It's an absolutely amazing keyboard to type on and is built like a tank, well worth the admittedly shocking price. However, the "tenkeyless" in the name means that it does not have a numpad. The keyboard is available with a numpad aswell, but the reason why I did not want one is that I am left-handed, and much prefer the numpad to be on the left side of the keyboard. A normal numpad would be almost useless for me.

Another reason why I got the tenkeyless version was this: not having a numpad also gave me an excuse to build my own! It's taken a year, but I finally managed to get around to doing it. That is what this post is all about.

Software Defined Radio

I've been interested in Software Defined Radio for a long time, but haven't done much with it so far. I finally decided to take my first step in actually doing some software defined radio hardware. One DIY SDR kit that I've had my eyes on for a while is the Ensemble RX II. It can receive anything from 1.8MHz to 30MHz. It's a simple and easy to understand SDR. I'm not into building readymade kits, though. So I decided to build my own clone of it instead. I figured you'd learn a lot more that way. So here's the story of that.

AD9833-based USB Function Generator

One tool that I've been missing at my lab at home is function generator. They tend to be a bit expensive, so I haven't bought one. I thought this might be a good opportunity to try and make one myself. I found a pretty common DDS (direct digital synthesis) chip, called AD9833. Then just strap a USB-enabled AVR micro there and maybe some analog electronics.

This board doesn't do any of the special analog magic to allow for variable amplitude or offset for the signal. The output is fixed to 0-4v. I'm planning to make another completely analog board for adjusting amplitude and offset.

A Simple EMF Probe

There's something fascinating about electromagnetic fields. Thanks to the modern world and the prevalence of electronics and electricity, they're all around us these days. But because of the extremely limited array of senses that we humans have, we spend most of the time completely oblivious of them. Wouldn't it be cool to make something simple that could not just detect them, but would allow you look at the waveforms on an oscilloscope. An EMF probe in other words.

Capacitive Touch Sensing with AVR and a Single ADC Pin

I've been thinking of a project that needs a little bit more elegant user interface than your usual push buttons. Partly inspired by a video blog on Dave Jones' EEVblog, I decided to look into capacitive touch buttons. The big issue unfortunately for me was that you usually need a separate chip for capacitive touch sensing. With some tricks, you can however use a normal microcontroller to do the job. Even using only a single pin and resistor.

Wireless Motion Sensor

Wireless stuff is fun! If you look at the picture above, the thing to the right, clamped to a vice, is a motion sensor (PIR sensor) that has a small addition on it's back. That addition is a small PCB that I designed, milled and soldered recently, with an ATmega microcontroller and a cheap radio-module on it. The thing to the left is a spectrum analyzer showing that the device is indeed sending radio signals. In the background you can also see a radio-controlled RGB light controller, but that's a story for a later time.

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