On Wed, 24 Nov 2010 16:17:50 -0600, "Jane_Galt"
wrote:
John Fields wrote :
On Tue, 23 Nov 2010 21:59:14 -0600, "Jane_Galt"
wrote:
John Fields wrote :
On Mon, 22 Nov 2010 01:01:01 -0600, "Jane_Galt"
wrote:
John Fields wrote :
On Fri, 19 Nov 2010 13:58:09 -0600, "Jane_Galt"
wrote:
Does anyone make a programmable appliance controller that can handle
fluorescent lights?
I want to be able to program lights so that they always go off at 10
PM but match the number of hours in the local day.
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I'm not sure I understand.
Do you mean that you want the controller to always turn the lights
on at something like "sunrise plus one hour" and always turn them
off at 10 PM?
What about daylight savings time?
No, I want them to always go off at 10 PM and be on the length of the
local daylight. So, for example, if we have 7.25 hours of local
daylight that day, I want them to come on 7.25 hours before 10 PM and
go off at 10 PM.
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So how do you plan to determine the amount of local daylight on an
ongoing daily basis??
Good question. If I were a programmer ( I'm not ) I'd use an ephemeris
table to pick the number of daylight hours each day and subtract them
from 10PM.
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An ephemeris is used to locate objects in the sky; what you'd use
would be a sunrise/sunset table:
http://www.usno.navy.mil/USNO/astron...a-services/rs-
one-year-us
In response to your original question, I don't believe there are
appliance timers out there that do what you want.
It sounds like what you're trying to do is mimic the duration of
natural daylight, indoors, with sundown being hard-wired to 10 PM.
If you're interested I can tell you how to do that.
Yes exactly. I cant figure how to buy something that does it, it would seem
to need a PC and an appliance ( not just incandescent lamp ) controller
that could be programmed by it. Kind of expensive.
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Depending on the size of the fluorescent lamp load, and since it's an
ON-OFF situation you're talking about, all you should need to drive it
is a relay or a contactor supplying mains to the ballast(s).
Arguably, the easiest way to do it would be to get a cheap PC running
DOS and then to write a program which would turn the relay on and off
at the proper times via the serial or parallel port.
Another option, of course, would involve the use of a microcontroller
running a program to turn the relay on and off.
In either case, what you'd need to do would be to keep track of real
time and then, using the sunrise-sunset table, turn the relay on and
off at the appropriate times.
Can you say your project's about?
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JF