Tuesday, September 17, 2019

diy lamp update

Some learning from five years outside. I have taken down my lamps to make changes. Let's see how they are weathering.

My concept was to build simple safe cheap reliable rugged outdoor lamps using common materials: wood, found glass, cheap LED chips and "wall wart" power supplies, all re-used if possible.

It was important to me that my lamps give efficient light without drawing attention to themselves.

This one (Model upside down L) is shown attached to a corner of my deck under the railing. I mounted it low, about knee height off the ground. The light shone downward on the path and was limited upward to the horizon by the top of the lamp. There was no glare from these lamps as you walked toward them, just illumination of the path. Would the design be classed as "full cutoff"?

I am pleased with the result. They were bright! Each used only 2 watts at 9 volts from an old printer power supply. The cost was about $5 each for new and reused materials.

[click any pic to enlarge]

A gray connector box is barely visible on the other side of the post. The wire carrying low voltage DC to the lamp passes through a hole in the post to the connector box. I tried to hide the wires and plug entrances for rain and bugs. Not very well it turned out.

I liked using old glass telegraph insulators for the lamp lens although I tried all sorts of glass. Some, like the insulator, were difficult to mount, especially for outdoor year round use.

The idea was that the glass object would protect the LED chip from the elements yet pass the light in a pleasing and interesting yet effective dark sky kind of way.

A common material I used was 2x4 lumber, usually without any protective coating so that the wood weathered natural grey. I avoided cracking of the wood by selecting evenly grained sections with no knots or visible cracks. I pre-drilled all the screw holes. Cracks did form over the years but they were minor.

I had intended for the lamps to look rustic in a modern way if that is possible?

These lamps were not connected this past winter but had illuminated the pathway perfectly for the four years before that, five years total. I didn't know if they still worked.

On the bench connected to a power supply!

Perhaps I shouldn't sound surprised?

Let's have a look inside. To do that, I have to destroy them.

One of the lamps has been a bug home for a while, the other is clean, apparently a better seal.

The bug is alive. No bugs were harmed in this research!

The seal was a bead of silicone around the skirt of the insulator where it touched the aluminum sheet. I had trouble getting the silicone around where the wires went through the sheet.

The thin aluminum sheet is a piece of natural finish roof flashing. It serves as reflector, heat sink and support for the bale wire. The glass hangs from the bale wire so that the silicone has backup. The glass insulators are relatively heavy. The aluminum sheet with it's attachments form a sub-assembly that gets screwed to the wood frame enclosing the electrical part from the weather. There is a cavity in the wood to fit.

It was crudely done.

The back view before removing the bale wires and peeling the aluminum sheet away from the glass. I can see that I used both steel bale wire (the thinner rusty wire) and aluminum wire (thicker and shiny). I recall that the aluminum was easier to bend to the required shape. The steel, although thinner was more stiff.

The smaller rectangles are pieces of aluminum bar to improve heat transfer to the thin sheet. The LED chip is mounted on the other side with two screws. There is thermal compound between the chip and the bar and between the bar and the sheet.

They don't look the same because I tried a couple of variations. The one of the left was a later model. Notice that the silicone fills the holes for the bail wires but not the electrical wires!

I'll bet that's the bug entrance!

In this pic, the bug house LED is the bottom one. Surprisingly clean.

The top one has suffered some rusty corrosion to one of the two bolts but not the other.

Both LED's still work as I showed with the bench power supply. I wouldn't count on the top one lasting much longer just by appearance. There seems to be some darkening at the top corners of the COB array potting.

This LED is from the dark sky shielded lamp. As you can see, it did not do well at all. The LED no longer works.

I had used a small glass jar as a lens for this lamp. I found that it almost immediately showed signs of moisture inside the glass. None of the screws I used were rust resistant and the lid of the jar rusted badly.

The connector boxes were ok although 2 of 4 became bug houses. Corrosion of the cover screws was a problem. The screw used is an unusual fine metric thread (M4x0.5 15mm long) so finding a suitable replacement is difficult. I like these boxes otherwise for outdoor use. The one has been in direct sun and rain for five years.

This autopsy of my lamps after their "life test" shows what needs improvement. My projects are never perfect the first time!

Your comments are welcome. Please browse the other articles in the series.

Thank you for over 55,000 pageviews of this DIY Lamp series so far!

George Plhak
Lions Head, Ontario, Canada

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

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