Is this dangerous?

[AndiFlatland]

I've not been able to get an answer which makes sense on this one yet, so I've come to the Answer Bank for help.

I've had several cassette machines over the years - yes, I still use them, and still find them very efficient! - and every one with a metal casing has caused a kind of light purring vibration on my skin whenever I've brushed my hand against it. It feels like it might be about to give me an electric shock, but so far touch... er, wood... it never has. What causes this, and is it dangerous at all?

[rojash]

I'm not sure what you mean by "It feels like it might be about to give me an electric shock". In my experience, thing give you a shock, or they don't - never heard of one that gave you a warning first!

Are these mains or battery? If mains, it's just possible that you are discharging static to earth through the casing, though as far as I know, most are double insulated and not connected to earth.

I would think that the most likely explanation is that you are feeling the vibration of the motor - in most tape machines, the motor runs continuously, even when the tape is stopped.

I have a Sony mp3 device which includes a voice recorder. it cost about 40 quid, records for hours, has no moving parts, and is slightly larger than a cigarette lighter. When I was in the UK on business recently, I recorded 52 hours of business meetings, and was able to back it up to my computer in Greece every evening over the net. Thats what I call very efficient!

[Disco Fever]

I have had this on my Sky box and other Sky boxes I have had dealings with, this is normally because the metal part of the case is not earthed as somewhere is says on the cover it is double insulated, the square within a square, I wouldn't worry about it but if you are then get out a volt meter and test between earth and the metal cover, anything over 50 volts is dangerous....