As I said I am drawing again the pcb as it is now, and please tell me if you
see something strange.

Regards

Tal Bejerano
AMC - ISRAEL


-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Olin Lathrop
Sent: Sunday, June 23, 2002 2:23 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: Hum problem


> Attach a quick schematic that I draw to explain my problem.
> The problem is a hum I can't rid of.

This is only the power supply.  It looks good enough assming that the
current drain doesn't cause the regulator input caps to droop below the
minimum regulator input voltage between power cycles.  You can easily see if
the power supply is at fault by looking at the regulated +12 and -12 lines
with a scope.  If they are flat, then the problem is elsewhere.  We can't
tell what the problem is without the rest of the circuit and some
particulars, like how much current is being drawn.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.