I alluded in a previous blog (Risk of shock) to the joys of valve radios, amplifiers and similar. Not quite the kind that you toasted marshmallows on, and I remember ‘acorn valves’, which were the first step in miniaturisation. They were easy. If they glowed, they were probably working, and if the wax capacitors around them were mere blobs, something had gone wrong. Of course in those days they took time to warm up: no instant sound. A bit like my digital TV and radio really … I remember it well But I also remember buying my first, small white…