PSN-L Email List Message

Subject: Re: Seismograph for school
From: "tchannel" tchannel@..............
Date: Fri, 29 Sep 2006 12:07:14 -0600

Hi Pete,  I have started the boards,
1.  Is the 5k pot a trim for gain?
2.  What is the 50k pot "offset" for and when and how is it tweaked.
3.  The C4,   4.4uF or 2.2 par.x2 are to be Non-polar, is this 
Non-polarized?  or the type without the +and - on the can.
I have 2.2uF I think non-polarized, If these work would I place the - toward 
ground?  I could not find Ceramic.
4.  On the .018uF could I sub .02uF?
5.  On the 1.5uF could I sub 1.47uF
I understand sometimes these value are critical, and sometimes not.  If any 
of them are ratio (as an example like this)  Fc=1/6.2832x R1xC1     I could 
adj the R's easier then the C's

Thanks, Ted

----- Original Message ----- 
From: "Pete Rowe" 
Sent: Tuesday, September 26, 2006 10:30 PM
Subject: Re: Seismograph for school

> Ted
> I'll be glad to send you PDF files of my schematics.
> Let me know
> Pete Rowe
> San Jose, CA
> ptrowe@.........
> --- tchannel  wrote:
>> Hi Stephen,  Thanks for this recommended site...I
>> could not enlarge the PSN Preamp and PSN filter Amp
>> by Pete Rowe, to see the values on the drawings.  I
>> searched the net but could not find any other site
>> for them.  Do you know where I might be abe to find
>> these, large enough to print?  Thanks, Ted
>>   ----- Original Message ----- 
>>   From: Stephen Hammond
>>   To: psn-l@..............
>>   Sent: Tuesday, September 26, 2006 11:38 AM
>>   Subject: RE: Seismograph for school
>>   Hi, I would like to add a few thoughts. There are
>> some simple plans on the PSN San Jose website.
>>   however, I strongly suggest that you look at
>> Larry's WINSDR software / equipment because in the
>> classroom, the software environment is one of the
>> most important attributes you need to consider. The
>> stability of the system hardware and software and
>> the quality of the information provided
>> significantly improves the students interaction and
>> learning outcome from using the system. For example,
>> if you look at the PSN San Jose main page
>> you will find
>> two links at the bottom left of the page to South
>> Valley Middle School and Los Altos High School. Both
>> schools are using WINSDR and Larry's hardware.
>> Initially when we built the system at Los Altos we
>> provided a PC, sensors and simple amp. At South
>> Valley, Jan Froom went though several steps getting
>> to the current system configuration you see today.
>> With the evolution of the Internet, there is a real
>> need to incorporate the seismic data into the
>> classroom websites. This simplifies the teachers
>> interaction with the system and helps to generate
>> significant student/parent interest in the project.
>> As you can see from the examples, by using the
>> automatic upload feature of Larry's WINSDR, the
>> sensor data is uploaded continuously during the 24
>> hour period. Another benefit is the amount of
>> interest the system generates outside of the
>> classroom. Look back at the Los Alto page and you
>> will see there have been over 24,000 trips to Greg
>> Stoehr's seismic science page at Los Altos High in
>> the last two years. Considering that he has about
>> 300 students per semester, this provides a 40-trip /
>> student page access ratio which is a significant
>> amount of return on investment. Greg keeps the
>> system in his classroom and his students take part
>> in operating the system during the class year. Greg
>> is extremely limited on the amount of time he can
>> spend on the system and WINSDR has significantly
>> improved his productivity. With a minimal
>> investment, you will see a vast improvement over a
>> simple classroom sensor and amp.
>>   Regards, Steve Hammond  PSN San Jose, Aptos
>> California
>>     -----Original Message-----
>>     From: psn-l-request@..............
>> [mailto:psn-l-request@................. Behalf Of
>> tchannel
>>     Sent: Tuesday, September 26, 2006 7:38 AM
>>     To: psn-l@..............
>>     Subject: Re: Seismograph for school
>>     Hi John,  Ted here, and I am one month into a
>> similar project, using my own money, for a non
>> profit organization.
>>     We are having a lot of fun on the project, but
>> the electronics are challenging, even though I have
>> worked on circuits, I thought I was up to it
>> electronic task, but now I am not sure.   I have
>> made some progress however, so I think I am getting
>> closer.
>>     I am happy to share my successes and failures if
>> you would like to correspond.  Ted
>>       ----- Original Message ----- 
>>       From: John Patskan
>>       To: psn-l@..............
>>       Sent: Monday, September 25, 2006 11:11 PM
>>       Subject: Re: Seismograph for school
>>       Hello everyone,
>>       Thanks for the tips.
>>       I believe I will try to build the Lehaman
>> style unit.
>>       This is actually an elementary school.  It
>> used to be an Environmental Science magnet school,
>> and they still have room they call the Eco-Lab.
>> Each class goes in there once a week and the
>> teachers have them work on some project.  This year
>> the teachers decided on a Geology theme.  I thought
>> a seismograph would be nice to have in the lab.
>> Actually I think the homemade one would be better
>> because the kids could get a better idea of how it
>> works.  They wouldn't be doing anything in depth but
>> I thought seeing there own siesmograph records may
>> spark some interest in science.  I Haven't
>> approached the teachers yet as I want to make sure I
>> can pull it off first.
>>       John P
>>       On 9/23/06, tchannel 
>> wrote:
>>         Hi Chris,  What sort of "choice of
>> suspension system" would you recommend? Is there a
>> detail I can look at?
>>         I have only seen the knife edge style.
>>         Thanks, Ted
>>           ----- Original Message ----- 
>>           From: ChrisAtUpw@.......
>>           To: psn-l@..............
>>           Sent: Saturday, September 23, 2006 5:09 PM
>>           Subject: Re: Seismograph for school
>>           In a message dated 23/09/2006,
>> jcpatskan@......... writes:
>>             I am thinking of trying to build a
>> seismograph for my son's school. I have quite a bit
>> of experience in shallow exploration geophysic's,
>> mostly electrical and electromagnetic, but none in
>> seismology.  I have searched the internet and found
>> quite a few resources.
>>           Hi John,
>>               You might consider making a medium
>> sized Lehman - about 2 ft long? Say about 1.5 sec
>> period that can be extended to 20 sec?
>>               You will need +/-12V stabilised power
>> supplies of you may buy an amplifier and transformer
>> from Larry at
>>               Since it will be used with other
>> school systems, I suggest that you use Amaseis and
>> buy a DI-154 12 bit ADC still at just $39!
>> Amaseis supports this ADC.
>>               See
>>               Use magnetic damping, NOT oil.
>>               Use an all metal braced single unit
>> costruction - NO plastic structural components - NO
>> separated sections.
>>               Your choice of suspension system is
>> critical. NEITHER a point on a plane NOR knife edge
>> systems are satisfactory - avoid them like the
>> plague. Most other systems are OK to good. You need
>> to be able to get a period of at least 20 seconds.
>>               Have a look at
>>               and
>>               and
>>               and
>>               ALSO
>>  and sequels
>>               I have also noticed a seismograph (or
>> strong motion accelerometer) on sale at e-bay, with
>> an opening bid of $75.
>>               I suggest that you forget this one!
>> You do not need a strong motion sensor - or the
>> headaches of converting an optical one. This might
>> be called 'buying trouble'!
>>               Good Luck!
>>               Chris Chapman
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