Power supplies are quite cheap (or free if you have a junk box like mine handy) ... try a few different ones ... It may also be worth while making up a separate plus and minus 12 volt regulated non switch mode power supply for the analogue parts of the electronics. I do this in computers where I need to get clean audio in and out. Mark ----- Original Message ----- From: "Larry Cochrane"
To: Sent: Wednesday, 5 July 2000 18:04 Subject: Re: noisy power supply > Angel and others having this problem, > > I have noticed this problem with some motherboards. This happens on newer > motherboards that have switching power supplies that place a lot of high > frequency noise onto the + and/or - 12 volt supply lines. This noise gets > into the multiplexor chip and op-amp on the A/D card. > > About two months ago I started adding two inductors to my A/D card that > filters out the problem. The modifications are easy too make, but require > some soldering skills. I will create a web page that documents the changes > needed to add the inductors if anyone wants to modify their board. Just > about any small inductor will work as long as the DC resistance is only a > few ohms. If you don't have a supply of inductors at hand I can send you > two if you send me > an envelope with return postage. > > If your not into soldering you can send me your A/D board and I will make > the modifications for free. All I ask is enough money for return postage. > > Too see if you are having this problem do the following using SDR. > Disconnect the 37 pin connector and press the "1" key and then the "C" key. > After a few seconds note the minimum / maximum counts from the A/D > converter. If you have a 16 bit A/D chip and the min/max count is greater > then +-8 the modification may help. With a 12 bit A/D chip the min/max > counts should'nt be higher then +-2. > > -Larry Cochrane > Redwood City, PSN > > At 11:44 PM 7/4/00 -0500, Angel wrote: > > > >Hi, > > > >I just got me new computer and much to my chagrin now all four of the > >traces on SDR are much noisier. Little spikes, jus ta few counts. When I > turn off the > >new computer the noise goes away and when turn it on the noise comes > >back. Obviously one solution is to not turn on the computer. Are there > >any others? > > > > > >Best regards, > > Angel mailto:angel@............ > > > > > >__________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email PSN-L-REQUEST@.............. with > >the body of the message (first line only): unsubscribe > >See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>