Ben Barrett wrote:
AC or DC? I have a few links to start out:
AC.
1-wire controllers:
http://www.aagelectronica.com/aag/en-us/dept_2.html
http://www.aagelectronica.com/aag/index.html (front page)
This is the first I've heard of 1-wire controllers. Is there
a Linux driver? How do you interface?
Digikey only seemed to have this 24V output module, in black or red:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=9085&Row=511138&Site=US
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=9085&Row=510961&Site=US
I did find some sealed solid-state 24V relays there:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=10099&Row=627139&Site=US
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=10099&Row=627300&Site=US
and an hermetically sealed model which is much more expensive:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=12192&Row=626000&Site=US
These links say "Your dataset has expired. Please search again."
I find Digi-Key's search engine lame. Search for "relay" and it
returns oodles of things not even closely related. With some
searches that's all I get. Fortunately with "relay" it actually
lists relays. But clicking on "solid state relays" it puts
me into another search engine. Narrowing the search in
any way returns "no matches".
In practice the only way I've ever been able to find anything
at Digi-Key is to call them and ask a human.
Perhaps my most interesting find:
http://www.cnc4pc.com/DC_Relay_Board.htm
This is tempting: http://www.cnc4pc.com/Solid_State_Relay_Board.htm
But since it uses triacs I'm not sure how well it would
work at the low power levels I am interested in.
Hope I'm not too far off-base here :)
Ben
Not at all.
http://www.mouser.com/omron/ was suggested by another person
off-line. That led to
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=210681&e_categoryid=160&e_pcodeid=65311
Which would likely work.
And the Omron G3NA-205B looks good. It operates down to 0.1A
and will do 3A without a heatsink. Since my load is 0.23A
continuous, that works well.
http://oeiwcsnts1.omron.com/pdfcatal.nsf/PDFLookUpByUniqueID/E03B55A4B7916E3C86256FC8005DC3C8/$FILE/D20G3NA0305.pdf
The input load is 6mA, which any TTL driver can manage.
By the way, here is a link to the rainbird 075-DV valve:
http://www.rainbird.com/landscape/products/valves/dv_series.htm
I haven't yet decided how to write the software. I think the
best approach would be layered.
* web page that writes config file
* cron job that reads config file
* port drivers [hopefully provided with the hardware]
The web interface would be written last, after everything else
was already working. Until then I could update the config file
with ssh from my main computer.
But I'm open to suggestions.
--
Allen Brown [EMAIL PROTECTED] http://www.peak.org/~abrown/
Two plus two does not equal five, even for very large values of two.
On 4/10/06, Allen Brown <[EMAIL PROTECTED]> wrote:
At least for this year 8 should do. In my wildest dreams
I can't imagine using more than 16. But I would be happy
with 8.
--
Allen Brown [EMAIL PROTECTED] http://www.peak.org/~abrown/
Ben Barrett wrote:
How many relays do you need? (How many distinct outputs/valves
to control?)
Ben
On 4/10/06, Allen Brown <[EMAIL PROTECTED]> wrote:
I want to set up a small computer (Linux of course) to
control the valves for watering my lawn. I'm thinking
of using the TS7200 as the computer.
http://www.embeddedarm.com/epc/prod_SBC.htm
That gets me a bunch of parallel outputs. Good for
controlling valves. But I need to control 24V. To
satisfy Corvallis that it is safe, the most straightforward
is to use relays between the computer and the valves.
Do you know of a suitable relay board?
Input control: 3V-5V
Output control: 24V @ 1A or more
--
Allen Brown [EMAIL PROTECTED] http://www.peak.org/~abrown/
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