late one : To earth, or not to earth...

tim at tim at
Fri Jan 9 17:32:56 CET 1998


Interesting Idea.  It can be done a simpler way.  The idea of using a double
insulated power supply is as you say quite common in the Hi-Fi industry and
in stuff like hair driers etc.

Basically all you need to do is separate the protective mains earth from the
system earth.  This is quite easy in a modular synth:-  Use a remote power 
supply whoose case is connected to the mains earth if its metal (this is a
vital safety measure!.  The system earth is then derived from the low
tension side of the power supply eg the transformers centre tap.  This
method is quite safe. 

So to summarise the mains earth is there for protection not as a refence
point (many places the neutral and earth are tied together at the mains
incomming point.




PS I'm away for a few days so if you would like a reply please bear with me.
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