I wrote yesterday about hacking a 220V AC walkway light to use 4 of our 7W LEDs. After testing it, it was painfully bright. We intend to put individual dimmer circuits on each light pole, but why waste money on unneeded LEDs just to dim them?

So we switched it out to a single LED design:

If you look closely at the center of the above picture, you will see there is a single 7W LED module pointing directly upwards. The light is mostly reflected off the of the mirror surfaces, spreading it out and making it less painful relative the the 4 horizontally mounted LEDs we tried in the first test. This spreading and reflecting was intended to soften it so it wasn’t painfully bright when turned on at night.

Since it is mounted pointing upwards, this reduced the space we have for a heatsink, so we took an old CPU heatsink from a broken computer waiting to be junked at the office and mounted the LED to it. Temperature tests show it at about 41 degrees Celsius after 5 minutes, which is quite a bit cooler than I expected. (Previous tests with the indoor lights were around 15 degrees Celsius warmer.)

This light setup uses 4x less electricity than the previous design, and it looks more pleasant when turned on:

Testing it outside at night showed that it worked quite well:

For a test of the amount of light, if I sit down on the ground about 5 meters from the light hold a book up facing towards the light, it is just barely bright enough that I could read the words. With the light off, it is pitch black. Since I am planning on having these lamps every 5 meters, this should be plenty bright enough to light up the walkway at night.