At 09:37  7/02/00 +0800, you wrote:
>Hi All,
>
>Anyone have any recommendations as to a simple to use real time clock? I
>am designing a small standalone environmental logger incorporating a
>16F874 and need to timestamp the samples.
>Any suggestions welcome (though mainstream vendors are preferred as I am
>in Perth, Western Australia).
>
World Wide Electronic Components have a range of RTC chips. They are in
Perth and their prices are good.
You can download a nifty catalog (DOS based).
http://users.wantree.com.au:8080/~worcom/
Another source is Bob Phillips (great guy) at Microzed.
http://www.microzed.com.au/
Alternatively, 3.2768 Mhz crystals are available from Altronics (Perth) @
$3.95 or Jaycar at $1. Coincidentally, I have just hooked up one of these
xtals to a 16F84 and used TMR0 and prescaler to generate 1 sec pulses. It
loses about 2 secs per day so I have to adjust the cap values. Tedious
without a frequency counter.

Can't help you with dust levels but I recall that Perth was a world leader
in air monitoring in the City when I lived there 20 years ago. Try your
great universities, UWA most likely.

PS. I can send you the code for above off-list if you want it.
Bob Jenner
Trading as RAJE Consulting
3 Cahill Cr Nakara NT 0810
Tel 08 89 455 796
Fax 08 89 275147
http://www.coolspot.com.au