I attach a video demonstration of a recent project. The tubular motor for roller blinds encloses a small induction motor. Due to its size, it gets hot very quickly. It has various built in features: Thermal overload protection Built in brake to allow doors to remain open or half-open Capacitor for fluent start and run… Read More

Yes, this motor is a beauty. While playing one of Bach’s two part Inventions the other day, I heard my washing machine give out a huge groan. I had left it on, rolling about while I played the piano. On concluding my playing, I went into the kitchen to find a pall of smoke and… Read More

SDI design circuit boards for – among other things – garage door control. The PCB here is photographed on an engineer’s formica table; that is a consequence of the honest marketing skills of an engineer, I am sure. The board shown is the main control system for our Symbolic Instruments panel. Populated sparingly as shown,… Read More

The following project presents a hardware device to produce random numbers. This is not an easy thing to achieve in any digital device. Software alone cannot produce random numbers. Why we should need them … is something upon which we shall keep our own counsel for now. It works on the principle of avalanche noise… Read More

I sometimes get asked about the security value of a key switch mounted right next to a shutter, open to any random burglar. It is supposed that you can take the front off the switch, then touch the wires together to get the shutter working.  So let’s see how we get on. First, remove the… Read More