Any electronics wizzes here?

[wmrcomputers]

I have PCB manufacturing ability, soldering skills etc, but my circuitry design skills are long outdated and I need a (reasonably) simple circuit diagram.

a 12vdc circuit which will run off such as a car battery. It needs a photo cell? to start a delay timer for around 8 hours once darkness falls. After the 8 hours it then needs to switch ON an output and then automatically switch off again when daylight returns (ideally at an adjustable level).

The purpose is a poultry lighting system to keep hens laying during shorter days as they need 15 or 16 hours of light per day. The artificial light has to be added at the start of the day so that dusk can fall naturally and allow them to put themselves to bed naturally. Although there are timer options, it means having to remember to adjust the on and off times quite often as sunset times vary. The circuit I am looking for would therefore be fully automatic as it would always turn the light on 8 hours into darkness.

Any electronics geeks here that could come up with the circuit diagram and list the components required? Happy to pay in computer repairs or eggs!

 

[Gramaisc]

Venner made a (mains) mechanical timer that, by means of a cam mechanism, turned on and off at sunset and sunrise, mostly for street-lighting purposes. You can vary the time difference from the actual sunset/rise times by an hour or two. That would give you the start signal for the delay timer and the power-off for the whole system - just the delay to organise then.

It needs to be initially set for the time of day and the time of year - and would be buggered up by power cuts.

 

[wmrcomputers]

Nice thought, but needs to be reproducable as we need to make several of these

 

[Studio Tan]

Can you use off-the-shelf items ? B&Q do this mains powered PIR sensor for £10 (see link below) which will switch up to a 1,000 watts. If you need more light power than 1000 watts, just wire the PIR to switch a relay (or relays) capable of handling more current to operate more lights (?)

http://www.diy.com/departments/iq-wired-light-sensor-pir-included/56353_BQ.prd

 

[Gramaisc]

Can you use off-the-shelf items ? B&Q do this mains powered PIR sensor for £10 (see link below) which will switch up to a 1,000 watts. If you need more light power than 1000 watts, just wire the PIR to switch a relay (or relays) capable of handling more current to operate more lights (?)

http://www.diy.com/departments/iq-wired-light-sensor-pir-included/56353_BQ.prd

He would like to run it from 12V, apparently, and it's the delayed start after sunset that's the hard part.

 

[Laurie61]

Maybe something like this- http://pi.cs.man.ac.uk/interface.htm http://www.pcworld.com/article/2598...uter-you-can-cook-into-diy-tech-projects.html

 

[wmrcomputers]

Again, a nice thought @Laurie61 but not what I'm ideally looking for. To an electronics wizz it would no doubt be a fairly simple circuit with just a few components - I just don't have what it takes to plan it out myself.

@Gramaisc you're right about the delayed start being the pain aspect of this. If it was a basic on at dusk and off at dawn I could produce the PCB in a flash, but then it wouldn't allow the hens to have a proper rest - and as much as I love their eggs I'm not going to be cruel

My only reason for saying 12v is that I know there would be a possible market for this beyond my own uses, and I would have happily come to some agreement with the developer. The lamp in a typical backyard coop could be a simple LED spot as they don't actually need a bright light. For now though I may just scrap the thought and trail a mains cable up to the shed as I've done previously and get a basic timer plug on the go along with a pigmy bulb to do the job. 6 hens are now only producing 2 eggs and we're using them quicker than they're laying them

 

[wmrcomputers]

I've gone for this Gramaisc. Will take a good few weeks to arrive from Hong Kong, but should do what I needed perfectly. A bargain too.
http://www.ebay.co.uk/itm/191219170523

 

[Gramaisc]

Looks plausible. Do you even need to turn the lights off immediately it also gets light outside? Letting them run on for a bit until you get up is no great detriment, I would think. At the time of year that you'll be using this, you'll be rising around dawn anyway...

It's the delayed start that you really need, after all.

 

[wmrcomputers]

I agree yes. I'm actually thinking of just setting a 24 hour program with this and doing away with the light sensor altogether for now. It means I'd need to restart it as darkness falls once every week or two to keep it "in sync" but that's no real hardship.

 

[Gramaisc]

The sunrise/set times change much less quickly during the real dark nights in the middle of winter than they do around the equinoctial times, such as now.

 

[wmrcomputers]

I've always relied on THIS in the past which has been quite useful