The assembly of this light circuit is straight forward and simple, and can light up your whole house in an instant upon power failure.
First off, you need the parts. They are available as indicated on the parts list:
1. The LED lamp is available on eBay for about $2.00 for a package of two lamps. They consume 6 watts @ 12 VDC.
2. Photo Eye works on 12VDC or 12 VAC. You can get it on eBay for $1.99 and it will handle up to 10 Amps.
3. The relay is 120 VAC, DPDT rated at 5 amps and is $4.99. Available from Marlin P Jones located in Lake Park FL call 561-848-8236 and ask for Barbara
4. The battery is a simple 12 V gel cell rated at 20 AH.
5. The charger can be a simple Harbor Freight trickle charge unit or a small $14.00 Solar Panel trickle charger from eBay, or work off a main solar battery bank.
6. The 2 fuse holders and fuses rated at 5 A.
... so much for parts.
All may be mounted on a perf board or fiber glass panel, etc.
Following are the pictures of the relay, LED (up to 10), battery, and solar or 120 VAC trickle charger types. Here are all the parts with the exception of a battery of your choice and a solar charger. The relay is shown along with power cord, 12 volt photo eye, 120 VAC relay, Harbor Freight trickle charger (best choice) fuses and fuse holders, the LED light and a small simple schematic below.
It has all been tested and the circuit works great. The asterisk indicates where to connect the trickle charger.
Best wishes ..... W2BTC ..... Bruce.
Here's an enlarged diagram.