Who knows what you’ll find in a second-hand shop? [Zeal] found some old keyboards made to fit early Alcatel phones from the year 2000 or so. They looked good but, of course, had no documentation. He’s made two videos about his adventure, and you can see them below.

The connector was a cellphone-style phone jack that must carry power and some sort of serial data. Inside, there wasn’t much other than a major chip and a membrane keyboard. There were a few small support chips and components, too.

This is a natural job for a logic analyzer. Sure enough, pressing a key showed some output on the logic analyzer. The device only outputs data, and so, in part 2, [Zeal] adds it to his single-board Z-80 computer.

It makes a cute package, but it did take some level shifting to get the 5V logic to play nice with the lower-voltage keyboard. He used a processor to provide protocol translation, although it looks like you could have easily handled the whole thing in the host computer software if you had wanted to do so.

Truthfully, there isn’t much chance you are going to find this exact keyboard. However, the process of opening a strange device and reverse engineering what it is all about is classic.

Don’t have a logic analyzer? A scope might have been usable for this, but you can also build one for very little these days. Using a PS/2 keyboard isn’t really easier, by the way, it is just well-documented.

What do you do when you’re a starving student and you need a 400 MHz logic analyzer for your digital circuit investigations? As [nanofix] shows in a recent video, you find one that’s available as an open hardware project and build it yourself.

The project, aptly named LogicAnalyzer was developed by [Dr. Gusman] a few years back, and has actually graced these pages in the past. In the video below, [nanofix] concentrates on the mechanics of actually putting the board together with a focus on soldering. The back of the build is the Raspberry Pi Pico 2 and the TXU0104 level shifters.

If you’d like to follow along at home, all the build instructions and design files are  available on GitHub. For your convenience the Gerber files have been shared at PCBWay

Of course we have heaps of material here at Hackaday covering logic analyzers. If you’re interested in budget options check out $13 Scope And Logic Analyzer Hits 18 Msps or how to build one using a ZX Spectrum! If you’re just getting started with logic analyzers (or if you’re not sure why you should) check out Logic Analyzers: Tapping Into Raspberry Pi Secrets.

We know [Happy Little Diodes] frequently works with logic analyzer projects. His recent wireless logic analyzer for the ZX Spectrum is one of the oddest ones we’ve seen in a while. The heart of the system is an RP2040, and there are two boards. One board interfaces with the computer, and another hosts the controller.

The logic analyzer core is powered by a common open-source analyzer from [Eldrgusman]. This is one of the nice things about open source tools. Most people probably don’t need a logic analyzer that plugs directly into a ZX Spectrum. But if you do, it is fairly simple to repurpose a more generic piece of code and rework the hardware, if necessary.

You used to pay top dollar to get logic analyzers that “knew” about common CPUs and could capture their bus cycles, show execution, and disassemble the running code. But using a technique like this, you could easily decode any processor, even one you’ve designed yourself. All you need to do is invest the time to build it, if no one else has done it yet.

[Happy Little Diodes] is a big fan of the [Eldrgusman] design. What we would have given for a logic analyzer like this forty years ago.