This wasn't exactly a design, but it was definitely a dumb mistake!
About 30 years ago I decided to replace the wimpy little radiant wall heater in my bathroom with a fan-forced heater, controlled by a separate 24 hour timer. After installing the timer and the heater, I turned the breaker back on. The timer made this loud growling noise, the fan put out a gale-force wind, and after a few seconds, wind-driven flames came out of the heater! In a panic, I turned off the switch, and after a little head-scratching, it dawned on me that the old heater was powered by 220V. DUH! **broken link removed** Why I had assumed it was 110V, I don't know.
Of course, the new heater was wired for 110V, and the timer was 110V. The timer and the fan motor were destroyed. I managed to salvage the heater by moving the resistance-wire terminals around so that they were in series instead of in parallel, I found a 220V fan motor at Grainger, but it had a smaller diameter shaft, which I fixed to accept the fan hub by making a shim out of some Mylar sheet stock. I gave up on the timer, because I couldn't find one which ran on 220V. I was tempted to get another new 110V unit and run it off one phase of the 220, but the cable in the wall was 2 wires plus a bare ground. I would have had to use the ground as the neutral for 110V, which I was not willing to do.
I'm a pretty good EE, but a lousy electrician.**broken link removed**