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Re: RAD Hard 555 timer



Bob,

I was wondering why you would use a 555 timer, other than it is well known
and easy to use. Is there a reason that you would not use a PIC chip, and,
with a simple program do your timing and be able to do away with the
resistors and caps that, I would think, be suceptable to temperature
extremes. I contacted our Microchip rep and he tells me that, while they do
not do RAD HARD parts, one of their distributors (Chip Supply - he is going
to send me more info) has the ability to put the chips in such a package.

Why would I think this might be a good idea. Partly because I have been to
some seminars (and I am impressed easily) where they powered the PIC's with
a grapefruit. They have a whole line of flea power chips. With the microamps
they require for power, it would be great for long life up there.

Another thought I had was, if the microprocessor circuit was powered only by
the new capacitors they have now that are really low leakage, could you
charge the cap from the solar power and run the micro just from that,
leaving the transmitter on solar/battery and configure the system such that
when the batteries were gone, the transmitter could be switched to work with
solar only.

Just my random thoughts.

Gene Harlan - WB9MMM
NEW - Name Tags by Gene
Harlan Technologies - publisher of Amateur Television Quarterly
ATVQ@hampubs.com
815-398-2683 - voice
815-398-2688 - fax
http://www.hampubs.com


----- Original Message ----- 
From: "Emily Clarke" <w0eec@AMSAT.Org>
To: "Robert Bruninga" <bruninga@usna.edu>; "amsat" <amsat-bb@AMSAT.Org>
Sent: Thursday, April 01, 2004 6:34 PM
Subject: Re: [amsat-bb] RAD Hard 555 timer



National Semiconductor has two that are space rated.  The part numbers are
the JL555SGA for the TO-5 and JL555SPA for the ceramic dip.

- Emily




At 11:04 AM 4/1/2004 -0500, you wrote:
>For our next PCsat we need a RAD-HARD 555 CMOS
>timer chip.  Normal ones draw 15 mA.  CMOS draws
>less than 1% of that.  This is the most critical part on
>the whole satellite.
>
>If anyone knows where to find RAD-HARD chips, please
>lemme know...
>
>Here is alist of MFR's only the CMOS ones will do...
>
>http://www.uoguelph.ca/~antoon/gadgets/555/555.html
>
>But I thought I would ask here before wasting a few days with
>phone calls to salesmen...
>
>----
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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---------------------------------
W0EEC - CM87tm
AMSAT Area Coordinator - San Francisco Bay Area
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--------------------------------- 

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