I have just wired in 35 12V LED light caps and down-lights on new deck. Looks great. Now I'd like them to automatically turn on about an hour before sunset and turn off (unless overwritten) about three hours later.

I'm wondering about best approach. Perhaps an analog circuit with light sensor that detects sunset (the previous evening), and then turn on lights 23 hours later, or maybe an Arduino with WIFI that downloads sunset data (not sure where I'd find this).

Any thoughts on the best approach is appreciated.

 

Usually irrigation/sprinkler timers are cheap and include a real time clock.
The output is usually 12v? AC so you may have to stick a bridge on the outputs for DC.
Max.

 

I have have lightbulb sockets that include both a timer and a light sensor. They do exactly what you want – turn the lights on at dusk and off some hours later.

You can also buy Christmas light timers that do this, also. They're suitable for outdoor use.

Like this: http://www.homedepot.com/p/GE-15-Amp-Plug-In-Dual-Outlet-Light-Sensing-Timer-15112/100685869

 

If you are thinking of an Arduino then you can calculate the time of sunset: https://en.wikipedia.org/wiki/Sunrise_equation#Calculate_sunrise_and_sunset

 

This timer may work for you.
It automatically adjusts for the differences in sunset time over the year.
You can set the time an hour earlier to get your 1 hour delay.

 

I have have lightbulb sockets that include both a timer and a light sensor. They do exactly what you want – turn the lights on at dusk and off some hours later.
...........

Not exactly.
He wants a delay at the start.

 

...I'd like them to automatically turn on about an hour before sunset and turn off (unless overwritten) about three hours later.

Not exactly.
He wants a delay at the start.

Not the way I read it.

 

Not exactly.
He wants a delay at the start.

No he doesn't.

I'd like them to automatically turn on about an hour before sunset

Darn public skool edukation done gott ya on da readin comprending again huh?

 

No he doesn't.
Darn public skool edukation done gott ya on da readin comprending again huh?

Well I sure do.
Read it several times and I somehow always read before as after.

But my solution in post #3 should still work.
He just needs to set the timer time one hour later rather than one hour earlier.

A photo sensor would not readily work unless you add a 23 hour delay.

 

http://www.homedepot.com/p/Weatherproof-Dusk-to-Dawn-Photosensor-DPPS/202188719

 

http://www.homedepot.com/p/Weatherproof-Dusk-to-Dawn-Photosensor-DPPS/202188719

I can only assume you didn't read the first post.

 

Thanks guys. I found this too "Arduino Astronomical Clock for Automatic Light Control." Think I'll try this route. Appreciate your advice.

 

I can only assume you didn't read the first post.

I read it, and thought, "A person can situate a retail sensor so the setting sun is mechanically occluded and thus adjust the start time."
Then I forgot about the 3 hour limit.
Then I doubted the O.P. is sure about what he wants. "Trigger something an hour before an event?"

Fact is, I have an over-designed sunset sensor with a timer very similar to this in my blog.
http://forum.allaboutcircuits.com/blog/night-detector.658/
Does the O.P want to build the deluxe night sensor and change the jumpers on the timer?
Get some education in analog design by trying to strip out the unnecessary parts?
When CdS sensors are now obsolete, and so it the timer chip?

Now that he's come back, it seems he wants an Arduino project.
OK. I'm getting obsolete.

 

If you are thinking of an Arduino then you can calculate the time of sunset: https://en.wikipedia.org/wiki/Sunrise_equation#Calculate_sunrise_and_sunset

requires GPS or other PS . . . input from

Astronomical Clock

-- this is one of the occasions where the no. of results displayed makes me wonder if we actually are at the 3-rd millenium of ̶h̶u̶m̶a̶n ̶̶ christian history :
Google?: Arduino "Astronomical Clock for Automatic Light Control" critics outdoor marine
track target: November 14, 2013

 

I don't understand why you would start an Arduino project to avoid buying something for less than $10 at Home Depot that is purpose built for the exact task.

The ones that detect sunset are adjustable. Face them east and they turn on at least an hour earlier than if they face west.

Now, they will come on earlier on a cloudy day. If you don't want that and really want to synch with the sun, then I suppose the hardware store options aren't up to it.

 

The timer I referenced in post #5 tracks sunset time and goes for $30.
But I suppose doing it with an Arduino is more fun.

 

I think it needs to be a two-pass algorithm. Record the time of sunset, turn them off 2 hours later, then turn them on 21 hours later. This is like the old lady who asks the kid: "How do I get off the bus at Mulberry Street"? The kid replies: "Watch me and get off two blocks before I do".

 

Now that he's come back, it seems he wants an Arduino project.
OK. I'm getting obsolete.

Typical modern day mentality. Anything that can be done cheaply, simply and reliably can be done more costly, complexly and less reliable as well and since it cost more and takemore to design and build therefore it's better.

Personally I don't follow the reason for turning the lighting on a full hour before the sun goes down.

What's there to gain? Is the sun not bright enough as is? If so why not just leave them on all the time?

Around here we have evening dusk light for about an hour after the actual sunset so by my reasoning turning them on a hour before sunset would have them running for nearly 2 hours for no reason whatsoever.

 

his is like the old lady who asks the kid: "How do I get off the bus at Mulberry Street"? The kid replies: "Watch me and get off two blocks before I do".

Or as the old Irish version of giving directions, 'Well, Firstly you can't get there directly from here." followed by a long drawn out set of directions that could have been summed up in one or two easy to follow sentences.

 

I don't understand why you would start an Arduino project to avoid buying something for less than $10 at Home Depot that is purpose built for the exact task.

The ones that detect sunset are adjustable. Face them east and they turn on at least an hour earlier than if they face west.

Now, they will come on earlier on a cloudy day. If you don't want that and really want to synch with the sun, then I suppose the hardware store options aren't up to it.

I agree, simpler is better. A lot cheaper. And it will work for many years.
I once built a sump pump controller, using metal probes, at different heights. It worked fine for a while...
But a simple float switch cost $10, and worked just a well. Also think of the environment your electronics have to deal with. Rain, moisture, temperature extremes. Just something to think about...