PSN-L Email List Message

Subject: Re: A/D
From: The Lahrs johnjan@........
Date: Wed, 13 Feb 2002 08:28:11 -0700

Hi Chris,

What I need is a 1-channel AD for use in schools.
The DATAQ DI 151-RS was ideal for school seismometer use, as
it could be used with the excellent software provided by DATAQ
with the unit or with Alan Jones'  AmaSeis software.  I would like
to see developed a very simple seismometer for classroom use
that when combined with an AD and AmaSeis would register
teleseisms from around the world.  If the cost of the entire
package (seismometer, amplifier, AD) can be kept under $150,
then this instrument could be proposed for use in the Globe
The GLOBE Program  - Students and teachers from over 3500 schools in 51 
countries work with research scientists to learn more about our planet. 
Students make and submit environmental observations via the Internet. 
Scientists use GLOBE data in their research and provide feedback to the 
students to enrich their science education and post student data sets daily 
on the WWW.

A lot of compromises may be required to get the price so low, but I think
it's possible.  A minimal school instrument need not be exactly linear nor
calibrated.  Need not be stable for months at a time.  Need not be sensitive
to only one component of ground motion.  Need not have a pendulum
period longer than 8 seconds - as an amplifier/filter combination will
still be able to pull out surface waves at periods of 15 to 20 seconds, as
is done with the AS1 instrument.

The other purpose for the AD is to record a small geophone on
a table top.  That's why the 240 Hz sample rate is specified.  This
is used in demonstrations, such as for the Table Top Seismology


>>Specifications needed:
One channel
sample rate:  1 to 240 Hz
AD sensitivity:  12 bit, +/- 10 Volt maximum
output: connect to serial port of PC
power: from PC serial port
price: $99 maximum ($50 preferred!)

>       What do you want to do with it?
>       You did not say how many channels you required?
>       Thurlby at do the VPS10 4 ch 12 bit 10 
> microSec @$135
>       Pico seem to want far too much
>       I think that they effectively charge for the 'free' software in 
> their module prices.
>       We really need someone to design a Kit boards that work with the 
> free software available!!
>       Regards,
>       Chris Chapman

* John C. and Jan H. Lahr
* JohnJan@........
* 1925 Foothills Road
* Golden, Colorado 80401-1718
* Phone: (303) 215-9913


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