A Galois Field Arithmetic Primer tomverbeure.github.io/2026/06/14/G...

Breaking Rohde & Schwarz AMIQ License Keys - the Hard and the Easy Way tomverbeure.github.io/2026/04/12/A...

Repair of 2 Agilent 54831 Oscilloscopes In the end, it comes down to fixing two early 2000s PCs… tomverbeure.github.io/2026/03/28/R...

Polyphase Channelizers with Frequency Offset - a Bluetooth LE Example tomverbeure.github.io/2026/03/05/P...

The Stunning Efficiency and Beauty of the Polyphase Channelizer tomverbeure.github.io/2026/02/16/P...

Complex Heterodynes Explained tomverbeure.github.io/2026/02/07/C...

Notes about Basic Polyphase Decimation Filters tomverbeure.github.io/2026/01/25/N...

Repairing a Self-Destructing SRS DG535 Digital Delay Generator

The Scenic Route to Repairing a Self-Destructing SRS DG535 Digital Delay Generator tomverbeure.github.io/2025/12/24/R...

Fixing LCD Screen Corruption of a Tektronix TDS220 Oscilloscope (and other fixes) tomverbeure.github.io/2025/11/03/T...

Inside an Isotemp OCXO107-10 Oven Controlled Crystal Oscillator tomverbeure.github.io/2025/10/26/I...

My new article on Harold Black and the invention of the Negative Feedback Amplifier has just been posted. I start the story with the invention of the telephone in the 1870s, to a patent lawsuit in the 1940s. Check it out. Let me know what you think. emedia.digikey.com/eMagazine-Vo...

I'm writing about self-hosting and got wondering why ports <1024 are privileged on Linux, and require you to be root to bind to them. Found this explanation and couldn't help but laugh. I'd always thought it was a bit of a hack. utcc.utoronto.ca/~cks/space/b...

Want easy capsense touchpad buttons? Just a PCB & 4 resistors. Coming soon to my Tindie store! If you want to make your own, files are here: github.com/todbot/touch... This demo in CircuitPython but also works in Arduino w/ my TouchyTouch lib #circuitpython #capsense #captouch #raspberrypipico

Cecilia Payne-Gaposchkin ✨ figured out what stars are made of ✨ when she was just 25. 🔭🧪 Her PhD thesis basically established the Harvard astro department — at a time when Harvard didn't officially allow woman students. I wrote this little profile to mark the 100th anniversary of her thesis:

Power Switch and Battery Replacement of an SR620 Universal Time Interval Counter tomverbeure.github.io/2025/08/19/S...

This is one of the most beautiful things I have witnessed, the craft here is impeccable.

I think AI hallucinated me into a paper about Modelling and Solving 2D Truss System! Something I know nothing about. A few days ago, I submitted a blog post to Hackaday. Today I googled my name to see if it had been picked up. Instead it found this weird hit. onlinelibrary.wiley.com/doi/10.1002/...

The Video Timings Calculator is my most popular webpage in Google Search by far, with most of clicks coming from Taiwan. Those are engineers working on monitors, TVs, laptops etc. Traffic drops on Friday morning and ramps back up Sunday afternoon. It also drops the week of Lunar New Year.

3 new features for my Video Timings Calculator: 1. 10K, 12K and 16K resolutions added. 2. HDMI 2.2 96/80/64 Gbps data rates added. 3. You can share timings by copy and pasting the URL. Thanks SnowSquire@github! Check it out here: tomverbeure.github.io/video_timing...

Repairing an HP 5370A Time Interval Counter tomverbeure.github.io/2025/08/10/H...

The SR620 time interval counter came to market around 1986, just before VGA was a thing. But analog oscilloscopes were everywhere, so it cleverly (ab)uses the XY mode to render images. It’s unusable on a digital scope, it’s readable on an analog one.

The HP 5370A time interval counter accepts an external clock of 5 MHz or 10 MHz to create a 10 MHz reference clock. The schematic is deceptively simple, but it's really interesting and I needed a Spice simulation to understand the basics: it's a cascade of 2 injection-locked oscillators (ILO).

Digikey box arrived with components for 6 different projects. What I should have done earlier is fill in the “customer reference” field for each component with the project name. Makes it so much easier to sort through the pile. This baggie has a 450V cap for my TDS 220 recap.

HP 5370A repair: I had the short isolated to down to the components around 2 transistors, or so I thought. Soldered power supply and input wire for easy out of chassis debug. 
The thing works totally fine and creates a beautiful 10MHz ECL signal. Now what???

There was (and is!) a short and a burnt capacitor on the clock reference board of my flea market HP 5370A counter. I was able to bypass the short with a bodge. After that, it works fine! The only thing not working yet is the circuit that was bypassed: the external reference clock input.

The HP 5370A time interval counter was one of the first to use an MC6800 CPU. To make debugging easier, it has a service board that can send the MSB and LSB of the CPU address to 2 DACs, so that programming execution can be tracked on an oscilloscope in X/Y mode.

www.youtube.com/watch?v=uhMC... I tried to make a convincing looking looking sopranos game

One of the flea market treasures is this heavy box that’s marked “Syntheziser”. No company or model name at all, but it must be HP, based on 1820-xxxx components inside. 5MHz in, 10 and 100 MHz out. After removing around 30 screws, you get to see this. Stunning.

A shiny variac, a high precision HP 5370A time counter, a back-breaking, broken (“it worked 2 months ago!”) Fluke 6071A signal generator and a nondescript 10MHz/100MHz clock synthesizer, all for $80. ‘t Was another successful Silicon Valley electronics flea market, but being there at 6am is rough.

This SR620 frequency counter is my best ever electronics flea market purchase. The manual has an earliest date of 1989, my unit has 1988 components in it. 37 years old. Excellent specs: SRS still sells this model, virtually unchanged! Mine generally works fine, except when it doesn't...

are you a platform/embedded developer? do you need to interact with hardware in a semi-custom manner? would you like to suffer a lot less doing it? if so, #GlasgowInterfaceExplorer might be for you. the code below is all you need to build a custom testbench:

Got myself a free wrench today!

The view of Barcelona from Montjuic castle is nice, but the star of the show is the sea port container processing yard around the corner. I spent more than an hour looking at mesmerizing dance of straddle carriers moving containers from trucks to storage to ships. Made me want to play factorio.

Hah, I have exactly the oscilloscope! … Wait a minute…

I’m reading this highly scientific paper about the award winning SERV CPU by award winning @olofkindgren.bsky.social.

Hurray! Weekend project complete and successful: DIP32 footprints installed after subjecting the PCB to hours of thermal torture and the scope still works! (Intermittently, but that’s why the operation was necessary to begin with…)

I spent 3 hours with a cheap(!) Yihua 948 vacuum soldering station, hot air station, and various YouTube techniques trying to desolder a DIP32. No success until I figured out the right technique with the SS-02 Solder Sucker. The second DIP32 was out 10min.

Great… ☹️

Not the first time that I say this, but for those in the back: Tektronix logic analyzer grabbers are fantastic. (And cheap on eBay!) Don’t torture yourself with the inferior crap that comes with Saleae, DSLogic and even some HP logic analyzers. tomverbeure.github.io/2025/04/12/D...

Testing if an RP2040 is fast enough to emulate a device with 120ns asynchronous bus (e.g. a 128KB SRAM.) Worst case, with a 200MHz CPU clock, the rp2040 needs 50ns to toggle a GPIO when it sees a rising edge input. It might be doable. The rp2040 is just too cheap to ignore.

My new (3d printed) toroid winding tool works great! Now I no longer have to count, my fingers don’t get muscle cramps and they look tidy.

The loot from today’s electronics flea market. I thought one 12GHz frequency divider was cool, but the seller only wanted to sell the 3 of them because “only one works and I don’t know which one.” So that’s a lot of extra volume in my garage. The totally working TDS 220 scope was $25 !!!

How can you owns such a beautiful piece of art oscilloscope and *not* clean it until looks brand new again?

#GlasgowInterfaceExplorer now has a high-performance SPI analyzer! it runs at up to 100 MHz (with some caveats) as an example, I wrote this tiny script that extracts data from SD card SPI transactions and lets me reconstruct an image file that an embedded device is reading

Oscilloscope Digital Storage, 1990s Style https://hackaday.com/2025/05/09/oscilloscope-digital-storage-1990s-style/

Brightness and Contrast Adjustment of Tektronix TDS 500/600/700 Oscilloscopes This is really simple, but I was *this close* to buying an LCD panel upgrade kit, so maybe it will help someone else one day. tomverbeure.github.io/2025/05/08/A...

I bought 4 loot bags at Anchor Electronics with Digikey and Mouser baggies and some SMD spools too and sorted them tonight. From left to right: resistors, resistors, capacitors, everything else. 3 of those 4 bags will soon end up at the SV electronics flea market for very, very cheap.

A Tektronix TDS 684B Oscilloscope Uses CCD Analog Memory tomverbeure.github.io/2025/05/04/T...

any excuse to repost the greatest Tetris story ever, when a reporter went to cover early e-gaming championships and discovered that his wife was unknowingly *the world's greatest Tetris player* by a huge margin archive.boston.com/news/globe/m...