Date: Mon, 3 Aug 2009 12:36:40 EDT
From: ewkeh...@aol.com
Subject: Re: [time-nuts] Method for comparing oscillators
<snip>
My goal is to keep the total material cost below $200. I have received
valuable suggestions from Bruce, some I am incorporating as long as it
does
stay with in the $ 200.00. I am a strong believer in KISS and have almost
completed the total PC layout. All IC's are DIP! The board is partitioned
in
such a way that it can be cut up in three sections or be left as one. Two
parts are Isolation amplifiers and mixer with all associated circuits the
third section separating the two sides is the counter. Price quote for
the
board is $ 22.00 in fifty and $ 30.00 in ten quantity. When complete and
tested all information will be made available to every one. The only
component
I have trouble buying is the 74 AC 112. Newark has them, but you have to
buy thousands. Material cost based on part searches is below $ 200.00.
Let me make clear I am not trying to push the limits of technology but
take
a conservative and KISS approach. Many will be able to make meaningful
tests where the limit will be their sources not the test set up.
What is missing is the two u Processor choices and the programming. I have
only limited knowledge in that field. I am looking for some one that is
willing to perform that task. The proper u Processors need to be picked
and
they will have to be programmed. Two of the identical three may be
something
like the PIC 1220. Once selected I can complete the board and order
prototypes. The programming should be simple, but that is easy to say for
someone
that never had to do so. Any body willing to help, please contact me.
Obviously PC software also has to be created, to use the data from the
five
counters. Any body that will do the programming will be a recipient of a
prototype board.
....<snip>
Bert Kehren
Digikey stocks the 74AC112E, and is available in unit quantities for $0.68
USD each. Price breaks for larger quantities.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-4223-5-ND
Dave M
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