Thursday, March 01, 2012

making a lamp from a 2x4

I am making this prototype of my ultra low power LED garden light from wood, probably spruce. This is the most common form of domestic construction material around here. It is not normally used outside but from my experience it will stand up well above ground and will turn an attractive weathered grey color with one or two years outdoor exposure. Certainly suitable for a prototype. The wood is easy to work with.

The 2x4 I am using had air dried indoors here for a couple months and shows no warping or checking. Because of the small pieces, it was easy for me to cut three good looking pieces without major knot holes. The step joint at each end gives a bit of additional strength and was easy to make with my radial arm saw. A couple of screws hold each end in place with the block clamped in the center until the weatherproof glue dries. The recess and the slots were cut with a router and a 1/2" bit. In this version, I have given the interior two coats of white paint to help defuse the light from the ends of the block outward.

The glass block slides snugly into the U. It will be fastened in place permanently to help weather seal the LED. On the prototypes I will lock it in place with a removable method of some type so I can get them apart. The half size glass block that fits this frame costs about $25 here, the LED about $20 so there is some salvageable value to the prototypes until I get things worked out with the design. I will seal the final version.

I've make some changes to this second version and refined it somewhat. The basic idea is the same. The LED which lights the block fits in a recess carved in the frame center, adjacent to the glass block. Here is a closer look. (click any picture to enlarge it)

This is one of six types of LED arrays that I have tried and which I will write about. This one is from Princess Auto, their product number 8381063, "5 x 2-3/16 in. Interior 10 LED Vehicle Light". It comes with a polycarbonate lens which I decided not to use, thinking that the glass block did a pretty good job of scattering the LED light.

Although the Princess Auto was not the brightest or most efficient LED I tested, it does provide a nice uniform light and is itself weather sealed. The first prototype which has been working outside for a month has one of these LEDs in it so I will be able to compare the orientation difference with the same source light. This one I plan to aim downward, rather than horizontally like the first.

This is a view of the end of the lamp frame showing the wireway for the electric feed. The wire will come straight out for horizontally aimed and down the slot for a vertically downward aimed fixture.

This LED from Princess Auto uses 111 mA at 12 VDC (only .111x12=1.33 watts) to provide 22.2 foot-lamberts of light in my tests. From the prototype already outside, this amount of light lets me see the stairway very clearly and the lamp is brightly visible even from the street 60 feet away. I made measurements of light output versus voltage for six different types of LED lamps that were available to me.

Thank you for your interest.

George Plhak

diy landscape lamp reading list
a very bright 1 watt diy led garden light
making a lamp from a 2x4 - this article
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


Ron Segal said...

Great project, minimalistic, elegant design. :)

To reduce costs significantly, you could source smd, led panels from China via Ebay.

I don't know how easy it is to find glass blocks here, but in any case you've got me started in a great direction.
Ron, Wellington, New Zealand.

george plhak said...

Thanks Ron, for your kind comments.

I have been getting LEDs from all sorts of places, including ebay. There seem to be new types available all the time at decreasing cost.

You might look for art type glass people as well as for the commercial blocks. It would be interesting to custom make the glass as well as the structure and light.

I am glad you find inspiration in my work. Please let me know how it turns out for you.

I really must write about the LED tests that I did since the method may help others select and then get the most out of their LEDs.

I found that the ones I was able to try varied quite a bit in terms of light output versus electrical input and that it was possible, if you had control of the power source, to "tune" them for best operation, best efficiency.


Ron Segal said...

We'll George your time and effort spent putting up such an excellent description is really appreciated.

Tuning, yes. Or maybe self-tuning. I was thinking of a small current controlled 'buck' type driver in each lamp of the type used in flashlights (again, or ebay). This would also enable a higher voltage to be used on a long run, i.e. so you wouldn't have to worry about voltage drop.

Seems that we can easily get glass blocks here in NZ. It would be fun to experiment with art glass and different effects, but basics first I guess.

Unfortunately my wife has now seen your article and is hooked, so even if I wanted to there's no escaping a project now!!

Will get back when there's some progress.

Best wishes, Ron