From: Rob Legg (legg_at_magma.ca)
Date: 2002-04-23 13:49:50
Joerg,
Your test set-up should attempt to duplicate end-use, particularly with the
power to the DUT. The measurement should not be affected by 250VAC of common
mode noise, if correctly configured.
I inquired earlier, why the sampling frequency wasn't chosen to reject
50/60hz interference, and was reassured that this hadn't been a problem and
wasn't expected to be a problem. Using a sampling frequency that does reject
this noise would seem to be a simple and low cost precaution.
It is odd to see ground loops forming when isolation stages are supposedly
present. Perhaps that is where you should be measuring - after the first
isolator, to obtain meaningful measurements.
Rob Legg
----- Original Message -----
From: "sleeper75se" <sleeper75se_at_yahoo.se>
To: <buildcheapeeg_at_yahoogroups.com>
Sent: Tuesday, April 23, 2002 7:15 AM
Subject: [buildcheapeeg] Re: TinyEEG update
> Hi Joerg,
>
> > The function generator is normally grounded and
> > the oscilloscope too. Are you sure, you did not
> > built a ground loop ?
>
> Ehm. No. You are right, I probably did. Could this be the cause? I
> guess a battery operated function generator is the only way around
> it.
>
> > Does the oscillation continue, if you disconnect
> > the function generator ?
>
> Unsure, I will have get back to you on that. It does not help with
> the 50Hz hum however, I can remember that much.
>
> Regards,
>
> Andreas
>
>
>
>
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This archive was generated by hypermail 2.1.4 : 2002-07-27 12:28:43 BST