Friday, February 24, 2012

a very bright 1 watt diy led garden light

I have been making my own ultra low power outdoor lighting with a view to saving energy while providing safe and reliable pathway lighting that looks good, is tough and inexpensive yet a bit different from the ordinary.

Up to now, I have been using reclaimed "Moonlights" from the local recycling center. I had placed them around the house to provide low intensity outdoor lighting, mostly of the walkways and steps. A tough electrical wire ran between all the fixtures and a power unit. Each plastic fixture took one bulb chosen for 4 to 11 watts brightness. Great light. Usually I used 7 watt bulbs in each fixture. They worked fine. They were inexpensive or free but they were breakable. When the clear plastic lenses began to get brittle and break from age I knew that I'd like to find a better way. The moonlights were also ugly.

I didn't much like the commercial offerings that are available in low voltage LED lighting. I have never been a coach light fan. The solar powered battery operated ones that didn't need wires were a joke. Not enough light and in two seasons they were dead. I wanted something that was bright, efficient, different but pleasant to look at, weatherproof for 10 years and made from ordinary (hopefully inexpensive) materials yet incorporating the latest in LED components.

I chose wood as the structural material. I am set up to work with wood rather than metals. A wood lamp will eventually blend into the naturally weathered wood deck.

This is only a prototype so the wood looks fresh and new on this dull day.

The glass block in the center admits and scatters the light from the LED array which is at the back of the block, buried in a recess in the wood. Power is via a low voltage cable that runs up the back.

The blocks I used are typically available at the home centers. Mine are products of Pittsburgh Corning [update 2019 - Pittsburgh Corning no longer makes glass blocks]. The one on the right is a "full" block of the "Icescapes" pattern, the one on the left is a half block of the "Decora" pattern. Both are end blocks which means that they are fully finished on one end.

Glass blocks make nice diffusers for the sharp edged light from the LEDs and they are virtually indestructible by weather. I thought of having some custom made, a little smaller perhaps or with a hand made pattern or color?

Here is a shot very early morning of two versions of the DIY LED Outdoor Lamp Project on my test pathway. Hard to photograph the way I actually see it but I will keep trying.

Thank you for your interest

George Plhak

diy landscape lamp reading list
a very bright 1 watt diy led garden light - this article
making a lamp from a 2x4
best light at least cost - about testing bright diy leds at home
diy testing of led lamps
diy 1 watt led update
diy garden lamp progress
a shielded low power diy garden lamp
diy lamp update

Wednesday, February 01, 2012

germicidal use for solar concentrators?

Respected Sir, Hope you will be fine. I am a university student in Turkey and doing MS Environmental Engineering. I am interested in designing and application of Concentrator Parabolic Panels as a reactor in waste water treatment. In this technology my basic purpose will be to use UV portion of sun light in degradation of water pollutants. I need your kind guidance in this project. Please guide me with what strategy I should precede and which areas are still needed to be studied, improved or discovered on which an academic research should be carried on.

Waiting for kind response..
Best Regards
Muhammad T
Fatih University Istanbul Turkey.

Hello Muhammad and thank you for writing to me.

I had thought also about using UV in concentrated sunlight for such a purpose. I am interested in your ideas about this.

The big problem is that the UV required for germicidal irradiation is UV-C (100-290 nm). According to the US EPA:[UV-C is] completely absorbed by the ozone layer and atmosphere. This is a good thing for us humans. There is such a small amount that even when concentrated, it may not be effective. Even at the concentration of my parabolic trough solar concentrator (about 18:1), the heat produced from the rest of the spectrum might boil the water before any UV-C sterilizes the microorganisms?

The glass of the reactor must be of a type clear to UV-C (quartz glass).

The water to be treated must already be very clear since particulates shield the UV-C. The water must be filtered to a high level (reverse osmosis?) before irradiation.

A correct exposure time must be determined for the radiation to be effective.

Successful operation of the system needs a test that the organisms are sterile and cannot reproduce since the UV-C does not kill them. Looking with a microscope, they will still be moving.

Do you plan to build a model?

Would boiling or distilling the water with concentrated sunlight be a better project? There is much heat available this way which can effectively kill all organisms, even in sludge. The UV-C is difficult.

George Plhak