Electronics ⁽²⁴⁾

I finally have a UTC clock (it does other stuff too). This is a QRP Labs Clock built from a kit of parts plus a GPS receiver, also QRP Labs. Very simple to build. It runs from 5V (pity it's not 12V but there you are) but I recently acquired a 5V linear PSU to run the three little LoRa boards rather than the 12V/USB charger I currently use. The kit is not yet finished - I need to attach the power switch and connect those two push buttons - but it's a neat little thing in a nice case. I was looking for a GPS locked UTC clock and recently built a kit which is also a 10MHz source and has a 10MHz OCXO to make a really useful device. That also has a clock display as well as other dispel modes such as satellites, locator and such but the clock is always about 1 second slow. Reading through the documentation from QRP Labs it transpires that this is because the 1PPS signal and the NMEA data can overlap, so the data stream from the GPS that shows date and time is not aligned to the PPS pulse which…

I built a thing! This is a GPSDO using a PCB and kit of parts supplied by G8CUL and a OXCO from G1OGY. It uses a Jupiter GPS module which provides the PPS signal and a 10kHz output and the completed module provides 2x 10MHz and 1x 1MHz outputs. Although there are a number of such designs this one is nice in that it also has a display and shows the current date and time as UTC. This was, I think my third SMD construction and certainly the Mose SMD devices including multi-legged chips. No issues in construction especially given the quality of the PCB that G8CUL had made. The backup battery is a CR2 3.3V type and helps with warm starting. As the regulator gets hot I managed to fit a heatsink between it and the rear of the case and hopefully this will sort out heat transfer, otherwise I may need to bolt another heatsink on the rear. Construction in a die cast box would have been better maybe but the blue/white box fits in with others in the shack, plus I had it already! The bezel is cut down from a 3D printed one from Printables.com designed…

I had a number of Molex pins to wire up recently. To make things easier I decided to use some 4-core signal cable I had but found that the insulation is so poor at resisting heat that soldering the Molex pins was a non-starter as it always ended up with bare wires. Of course, Molex pins are designed to be crimped... so off to eBay. The latest addition to my toolbox arrived in a couple of days and made the job a lot easier.

Some of you may remember that I used to collect valves. I started collecting when I was around 6 years old, although back then it was more to impress friends than collect. An old directly heated valve plus a Lego battery box lit my desk up at primary school. I did not start collecting in earnest until the 1990’s and launched my first online valve museum in 1999. Since then the collection grew in several directions at once, including German WW2 types, Russian Cold War types and British military and civilian types. There were specials from all over the world as well including a few Japanese WW2 ones. Valves ranged from tiny little things to a RD150YB that had to live in the garage, and a 6-anode mercury arc rectifier that was equally not allowed in the house, and for good reason too. The main collection grew to over 3,000 types, many of which had duplicates, so probably 4,000 in total. And then there were boxes of valves that did not warrant adding to the collection. And so the collection continued to expand. While on holiday in the US friend in the US was discussing collecting trends with me and…

"Zilog has called time on the Z80 CPU." (https://www.theregister.com/2024/04/29/opinion_z80/) Wow. Actually I had no idea (through never having checked) that it was still being produced. And a fine chip it was too. I never built a system from wires up using the Z80 though. My first system, designed, built from chips and wire-wrap was an 8080 system, hand programmed to control al x-ray diffractometer. This was decades ago now but I still remember it, although I have no photos unfortunately. The system had a timer chip for a 1-second count and was interface to a Nuclear Engineering (I think it was!) counter that used nixies. But I did at least use Z80s, just they came as boards. The first was a Transom Triton computer and by then I was programming in Turbo pascal - back then this was really neat as one could have procedures full of assembler code which made interfacing easy. Later I used Gemini boards and that also gave the ability to have a graphics card. By then my interfacing to the diffractometer included a stepper motor and shaft encoder to control the arc motor. In the end there were two sets of Gemini Z80 boards, one…