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@@cornnatron3030 Good solution! I have a spare that's mounted the other way round, so I can save a holder. Nice, thanks for the suggestion

@@MarkBesaans That was after cutting around 60% of the story.

Well, there was The Accident. I was using a pressure washer to clean out a blockage in my septic tank connection from the house drains. I was using boiling water and drain cleaner to help dissolve a mini-fatberg. Somehow I got both ankles tied together with the power washer hose, while I was moving rather rapidly, and fell forward as an appreciable fraction of the speed of light. I missed the open septic tank hole, which might have ended up with a fatal result, but I fell on to a low brick wall with a sharp edge, landing on my right forearm. Unfortunately, I was carrying half a gallon of freshly-boiled water, and it all spilled out on to the back of my other hand. My ribs hit the pressure washer, and I damaged my ankle and knee as well. Luckily I was only ten paces from a cold water tap, so I hopped over to it and ran icy water on the burn for ten minutes. Then I realised I had no cellphone coverage, and no landline phone, none of the neighbours were around and Rose was away. I was starting to go into shock, so made the decision to hop to the car on my good leg, clambered in and drove with my good left foot on the throttle and brake, and my rather damaged right hand to steer. Car is automatic, so it wasn't too hard about from using the wrong foot. I got to the local hospital and was seen within three minutes. They fixed me up, cut away the burnt skin, took X-rays and applied fancy dressings. No broken bones but my arm was black from the wrist to above the elbow, with a gigantic haematoma like half a melon on it. I still can't type properly, nor use a mouse, and my right shoulder is messed up, I can't hold a screwdriver or pen very well, and my grip strength is poor. Left hand burn took AGES to help up, but I had excellent support from the wound management and specialist burns folks, and now it's hard to tell it was ever scalded. That's HALF of the reason I've been absent. The OTHER bit is a lot more exciting...

Now for the GOOD news. I've been commissioned by the same TV series that I did the Great Seal Bug for. This time, the task is hugely more complex. I have to make a replica of a piece of historical equipment (well, two actually) from 100 years ago. I am working 80 hours a week on the project. I've already machined over 240 separate parts of the mechanism, and in two weeks I have to have it all working and go to a secret location to meet up with the presenter and crew to explain and demonstrate The Machine. I am at least ten days behind schedule, but that's normal for me. I need that impending panic to get my ADHD-ridden brain to go into hyperfocus and get stuff done. I can't talk about the details until the programme airs some time later in the year, but I've been recording what I can so I can make a series of vids about it after the release date. After the studio session at the beginning of September, I'll be able to get back to making videos. I have about 60 hours of project work on video, with a lot of material about getting to grips with the new CNC machine.

I should do a few community posts I guess, but every waking hour is spent doing CAD or experimenting or machining stuff for Project Narwhal, and I'm seriously short of sleep. This is all written using the rather splendid voice dictation service in Windows 11 so I don't need to type other than edit a few words. Marvellous thing, technology.

@@bluegizmo1983 Indeed, but with spatially-varying wall thickness. Gyroid lattices guarantee no internal voids and by varying the equation in all three coordinates, you can achieve a varying refractive index across the bulk of the lens.

External 1 GHz radio signal is beamed at the device. Sound waves vibrate the metal foil membrane like in a condenser microphone. That changes the resonant frequency of the microwave cavity. As the tuning moves towards and away from the external signal, the response gets stronger and weaker, thousands of times per second. The re-radiated signal is mixed with a sample of the illuminating transmission and the receiver uses the homodyne principle to recover the audio. Mathematically, the modulation produces sine and cosine components with a frequency of 1 GHz plus the audio frequency and 1 GHz minus the audio frequency. Multiplying those by a sample of the 1 GHz alone results in products back in the audio range. Similar to a direct conversion receiver, but that has its own local oscillator. The clever trick is to use the original signal as the local oscillator, so you cancel out any drift and most of the frequency instability caused by microphonics in the transmitter oscillator. Have a look at czcams.com/video/1iG6bOpgYes/video.htmlsi=CplRRXdapmxbYuaa&t=48 where Davis Ricketts explains the homodyne concept. The start of the video covers the mathematics