On Wed, 14 Sep 2011 05:44:06 +0000, xavier wrote:
:: What do u mean by galvanic isolation?

It means that that the input to your system is physically not connected to=
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the output.

You might want this if you have mains AC on one part of your circuit but=20
for safety reasons the output side mustn't be directly connected.=20

If your Pic is powered via a transformer (for example) then the dc side of=
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the transformer is galvanicly isolated from the AC input side. If your Pic=
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is power directly from the AC (using suitable voltage reducing techniques)=
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the Pic would not be isolated form the 50/60 Hz mains and therefore if you=
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were to touch it, you are in danger of giving yourself an electric shock=20
(fatal possibly).

Apart from the above, you might also want to isolate a circuit if you are=20
connecting it to a computer, if your circuit shorts out, it is less likely=
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to damage your PC and of course the other way around, this type of galvanic=
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isolation is often made using an opto-coupler. If you have a modem or a=20
network card there will be a transformer that isolates the circuit from the=
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outside world mainly in the case of the phone line to prevent telephone=20
technicians getting a shock if someone's computer or router or modem=20
suddenly had high voltage or mains voltage applied to it.

It can also (but probably not in your case) be used where equipment might=20
have a voltage difference between grounds - this can happen when many=20
pieces of equipment have to 'talk' to each other over great distances or=20
between buildings like on a large industrial estate/site.

Colin=20
--
cdb, colin@btech-online.co.uk on 15/09/2011
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