PSN-L Email List Message

Subject: Re: Electronic Drawings for Lehman
From: Larry Cochrane cochrane@..............
Date: Tue, 06 Jun 2000 12:21:00 -0700


The electronics need for a Lehman is pretty straight forward. After the
pickup coil, I use a 220 volt AC relay coil, you will need an amplifier,
maybe a low-pass filter and some way too display the information. This can
be a chart recorder or a computer with an A/D card and software. If you use
a chart recorder the low-pass filter probably isn't needed. If you use a
computer and A/D card you should have a low-pass filter between the Amp and
the A/D card. 

For a schematic of an Amp / Filter board see If you don't want to make your own,
check out I also have an A/D card and
software if you want to go that route. See for more info.

Larry Cochrane
Redwood City, PSN

At 01:23 PM 6/6/00 -0500, you wrote:
>I would like to know if anyone has available schematic diagrams for the
Lehman seismograph construction.  I understand a great deal of the
mechanics for such an instrument however my knowledge of electrical systems
and components is limited to the benefits of light switches and the like!
>I have CAD capabilities (microstation or AutoCAD) so if electronic files
are available I would appreciate it if they could be forwarded.  If hard
copies are available I will send a SASE and gladly pay for any reproduction
>Thank you.
>John Finke, P.E., S.E.


Public Seismic Network Mailing List (PSN-L)

[ Top ] [ Back ] [ Home Page ]

Larry Cochrane <cochrane@..............>