Tinker, Tailor, Soldier, Sailor I like to tinker with old fashioned thermionic valve circuitry - tubes, for the 'Merrykins. It is strangely crude and simple and they make a friendly orange glow in the evening. However, powering the things is hard, due to the high voltages that are required to overcome the vacuum. The below picture shows how I build these toys. It happens on the fly. This is a hobby, so I don't kill myself with design calculations. The tag strips enable experimentation to adjust things till it works properly. The VU Meter even has a little transistor in there - sheer desperation! Transformerless Valve Power Supply One can use transformers, but they are big, heavy and expensive and shipping hunks of metal around the world make it even more so. It makes sense to use transformers if you build a high power circuit with multiple valves, such as a guitar amplifier, but a small circuit with only one or two valves presents a problem. ...
Autonomous planes, trains and cranes...