EEG isolation best practice?

[Bill Knight]

I need to isolate an EEG amp from associated mains powered circuitry.

I hesitate to us a single opto-isolator IC.

What is the next better option that is avaialble off-the-shelf?

Maybe a discrete opto pair and a length of fibre cable? Any specific
recommendations?

Bill

 

[Paul Burke]

Bill Knight wrote:

I need to isolate an EEG amp from associated mains powered circuitry.

I hesitate to us a single opto-isolator IC.

What is the next better option that is avaialble off-the-shelf?

Maybe a discrete opto pair and a length of fibre cable? Any specific
recommendations?

If you want rather more margin than the standard package, you could use
a BASEEFA type, they have a long barrel shaped body and about 10kV
isolation. Farnell has Optek OPI1264A and others.

Paul Burke

 

[Steve Roberts]

Paul Burke <paul@scazon.com> wrote in message news:<2h0mu9F7imqjU1@uni-berlin.de>...

Bill Knight wrote:

I need to isolate an EEG amp from associated mains powered circuitry.

I hesitate to us a single opto-isolator IC.

What is the next better option that is avaialble off-the-shelf?

Maybe a discrete opto pair and a length of fibre cable? Any specific
recommendations?

Burr-Brown ISO100, just attach power supply at both ends, and add a
offset to your signal at one end and subtract it at the other. Burr
Brown makes a lot of transformer, and optocoupled isolation stuff, but
the single ended ISO100 is the cheapest and has a long linear package
designed for this sort of thing.

Steve Roberts

 

[Rene Tschaggelar]

Bill Knight wrote:

I need to isolate an EEG amp from associated mains powered circuitry.

I hesitate to us a single opto-isolator IC.

What is the next better option that is avaialble off-the-shelf?

Maybe a discrete opto pair and a length of fibre cable? Any specific
recommendations?

To start with, you need a line filter without Y caps, the a transformer.
To avoid the usual capacitive coupling that rises the secondary to
line/2, get a transformer with an earth screen between primary and
secondary.

Then beside the signal separation with optocouplers, you also need an
isolating supply. The supply and the signal isolation have to
be of the same isolation type.

And yes, there are seperate rules what medical electronics concern.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

 

[N. Thornton]

Paul Burke <paul@scazon.com> wrote in message news:<2h0mu9F7imqjU1@uni-berlin.de>...

Bill Knight wrote:

I need to isolate an EEG amp from associated mains powered circuitry.

I hesitate to us a single opto-isolator IC.

What is the next better option that is avaialble off-the-shelf?

Maybe a discrete opto pair and a length of fibre cable? Any specific
recommendations?


If you want rather more margin than the standard package, you could use
a BASEEFA type, they have a long barrel shaped body and about 10kV
isolation. Farnell has Optek OPI1264A and others.

Paul Burke

Medical isolation requirements are severe: you need to know what they
are and follow them.

Regards, NT