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 is the actual timestamp. Thus if you feed that data to a clock display it runs slow. (being lazy and saying GPS everywhere, I should really use GNSS!)

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 specifically for the 2x16 LCD displays. The button - which is not the best but I had one etc. - selects the various displays which include date and time, satellites seen, latitude, longitude, altitude and QRA locator.

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 another collecting friend and said he collected US antique types, others collected microwave types and, pointing at me he said I collected everything and there is nothing wrong in that. But it made me think what exactly is my interest. And so I decided to concentrate on what I found most interesting - British military types, mainly in the CV, and A, N and V military series. The collection included a number of CRTs as well and eventually took over the whole garage. I decided then to concentrate solely on CV types and trimmed the collection to 1,500 types, again with duplicates taking the collection to over 2,000 valves. Of the remainder many were sold and many hundreds went to the National Valve Museum which was nearly as old as my own. Eventually though three things happened. First, it was becoming increasingly difficult to find new additions. Second, the website was now seeing fewer and fewer actual hits (as opposed to search engine spiders), and, most importantly I realised it had become an obsession. Time to quit. I also came to the realisation that I had an awful lot of valves in lots of boxes and I never even looked at any once they went into a box. So I decided to close the website and sell off anything I could, donating the remainder to the National Valve Museum. The website was essentially converted to flat HTML files with none of the database behind them and taken over by a member of the BVWS. Of course, all praise to them for doing that, but none to me for all my years of work. Par for the course. In the past 20 years I received just a handful comments thanking me for providing the photographs and information about the collection. I…

"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 for the x-ray diffractometer and one for an optical microdensitometer. Both gathered data and were interfaced to a mainframe computer for the processing using a suite of Algol 60 programs. Good old days... Personally my first system was a 6502 Newbear single board, followed by the ubiquitous Nascom 1 which was, of course, Z80 based. Farewell, Z80...