I don't know if I've posted this before, but at my last place I had something very peculiar happen. I had an early version of radio door bell, as I couldn't always hear the original, and could carry the speaker round with me. Unfortunately, the speaker ate batteries fast, but it did have the option of plugging in to the mains, which I usually did. This only happened when it was plugged in.

One day, the bell rang, I went down (I had an upstairs maisonette) and there was no-one there. Or anywhere near. This became repetitive. I had two possibilities in mind. That someone had a similar device, and I was picking up their signal, or that the son of a family two doors away was playing Knock Down Ginger. The first I could eliminate - I'd been up the road collecting for charity, and there was one other version, outside the range of the receiver. The second I could eliminate by looking out of the window upstairs quickly enough to spot any movement. There wasn't any.

I added the possibility that it range when someone affected the current somehow, by turning something on or off (it was often close to the hour), and stuck a notice by the bell push, asking people to ring twice.

The false signals started doing it twice. Then, one evening when I happened to have a bunch of physicists in, it went completely haywire and built up the number of rings (I think I had put a new notice requiring three rings, which was followed by the next false event). I think it started to respond to the mere suggestion that I up the ante, and got as far as five rings. There was no trace of anyone in a position to enjoy the results. I asked an AA man in the road if he had been doing anything to the car he was working on that would have caused sparking. No. I rang the electricity suppliers the next day to see if there had been any surges. No. So I took it back to Argos, who insisted on taking it away for a refund - I had wanted to keep it and have a good look inside, but no chance. I didn't ask the person with the same model up the road if they had had problems.

There was no-one in my block, except the boy, who would do anything like it, and no-one with the skills. It was very weird that evening.