I think you'r in for some flak on this. Read Olin's post again..he can sound curt at times but he is right here.. PSU output Caps are an important part of the Unit (they stop/reduce ripple on the supplt line). Art. ----- Original Message ----- From: "Tal Bejerano - AMC" To: Sent: Monday, June 24, 2002 12:48 AM Subject: Re: [EE]: Hum problem- draw it again > I draw again the PSU section. can you tell if all grounds ok? > I didn't put all components (OPamp and it components) in place, cause I need > to know if the PSU is ok in this position. > next, if it's ok, where I should connect the ground to the preamp? to the > same 0V point? > mind that I didn't connect the PSU's output caps yet. > furthermore, do you think I need mains ground? > > > Regards > > Tal Bejerano > AMC - ISRAEL > > > -----Original Message----- > From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On > Behalf Of Herbert Graf > Sent: Sunday, June 23, 2002 9:13 PM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [EE]: Hum problem > > > > >I don't have a scope so I cant see what is going on, don't be offended I > > >have to work "blind in the dark". > > > > Tal, it looks like you are just like me, "in development" ;o) > > > > I have a tip, that may or may not work for your problem > > > > Use a common speaker, with a resistor in series, in the > > output of your power supply > > > > If you have ripple in your PSU, it can (or not) be > > determined with this simple hack > > > > In my pinball repair times, when there wasn't a scope > > avaiable (always), this was something that could find a shorted > > diode or a dried cap on the psu. Dunno if it will be of use to > > you, but here it is anyways ;o) > > Interesting trick. A trick I have used is to hook up a true RMS > meter to > the DC line, if there is ripple it shows up on the meter. It's not super > accurate but it gives a qualitative result (ie. there is more ripple then > before). TTYL > > -- > 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.