Al, (Repeat from Sep 11 post:) For some time I have posted the schematic of the seismic preamp and 4-pole filter that has been used in over 100 telemetry stations from Alaska to Greece. The filter design is from the NASA filter handbook (details posted). The schematic shows options for frequency scaling, as for a 2.7 second "Wood Anderson Seismometer" response that works well in an urban setting (the vault on SLU campus) with a 15-second long period seis like a Lehman horizontal as input. The cmos 4250 amplifiers can be replaced with more available higher power devices if battery operation is not needed. http://www.eas.slu.edu/People/STMorrissey/index.html stmmisc.html" PSN INFO ... SLU Seismic Network Regarding the artwork for the seismic preamp/filter. I can send a photocopy of the original artwork, 2X scale, black lines on white or a transparency copy of the actual printing film (which I doubt is dense enough to photo-print from), if you send me three stamps and an address. It really isn't that complicated, as you can see from the scan of the foil side of the board shown on the web site. And if I were to make only one or two, I would use perforated board with foil pads. Vector 3677 is 4" wide and has 22 gold plated edge connectors; cut lengthwise and trimming off one connector makes the 2" x 6" to 8", 10-pin connector board that fits inside the tennis-ball can that is used for a housing. I have used this board for as many as 6 prototype circuits; once one is laid out, duplicating it is easy. Regards, Sean-Thomas __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>