PSN-L Email List Message

Subject: Re: Homebrew AS-1 seismometer
From: John or Jan Lahr JohnJan@........
Date: Sun, 27 Mar 2005 21:17:20 -0700


Good job of finding a spring!  Do you have some photos of your unit?  I think it would be good
to post some, along with your spring details, on my web site.  Are you using AmaSeis?  If so,
it would be interesting to save a 24-hour screen image of the next good sized event.  We could
compare it to one of the local AS1 posted here:


At 07:49 PM 3/27/2005, you wrote:
I just completed a homebrew AS-1 seismometer.
I must say the most challenging part was trying to find a boom support spring.
Having no engineering degree so I was left to do the trail and error method. I got very lucky. I just had a new LOWES lumber/hardware store open very close to me.
Being a new store their stock was full and complete. I found a spring manufactured by Century Spring Corp.
The part number on the package is "C-219". I purchased two of these springs.
I had to do some resizing of these springs. The spring is 4.5" long. I cut about 3/8" off of each coil. I then spread the coils of each spring just far enough apart to mesh them
together (about a 1/2" overlap.)  I happened to have a 1/2" i.d. x 1" spacer in my junk bin so I slid the spacer over the meshed coils so they will not separate.
I ordered a coil and magnet for Larry. The amplifier is from the following URL a power supply for this amplifier
can be found at .
When I started this project I requested a catalog from Century Spring. I can not find a spring with a C-219 part number, but there is a spring with the part
number of 302 that is a very close match. Another spring that could be tried is the 119. This one would have to be cut to the desired length. Century Spring has
a minimum order of $30.
I must say that the sensitivity appears to be superb as compared to my Lehman (but it's never been quite right after I rebuilt it.)
All of the mechanical bits were purchased from LOWES.
If you would like more information please contact me at n0ssy@........... and not through the PSN list server.
Dewayne Hill
Westminster, Co.

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