25
Jan
08

rbt’s highpower ledspot (eng. vers.)

Highpower-leds facinated my right from the time they got available on the consumer-market. I still remember my first sample, a blue „lumiled“. Compared to the normal 3 oder 5mm leds, colour and intensity were just stunning. Now i was infected by this terrible virus and i used the hp’s wherever it was possible . Like everything bright and shiny this little fellows carry a small hook – they require passiv cooling.

Today, highpower-leds have a growing number of fans and other manufacturers offer interesting models in different power classes. The development got a huge boost over the last 1 or 2 years, efficiency and max. luminous flux are the key features leading the engineers . 1W Leds got pushed away by 3W and 5W models, only topped by the +50€ class with over 17W. But let’s take a look on my own project now.

Concept

The basic idea behind this project was kinda simple: kick out the old fashioned bulb and use leds instead. The lamp of choice was a counterweight by Hadrill & Horstman from the 40’s or 50’s and should stay untouched. Cooling and powersupply had to stay close to the size of an ordinary lightbulb. To keep it simple i used the original mounting ripped from the lightbulb.

Sry i dont have better picture … she’s a bit shy and hides behind the screen.

Before i could start drawing i had to look for the right leds and a small powersupply. After some research i picked up 3 „Seoul Z-Leds“ for 8€ each. Supplied with 350mA you get an output of nearly 100lm ( 240lm max on 1000mA). Cold white light helps me to stay alert on lonely night at the desk.

The Powersupply i choose, is a small 1A model. To run the leds on full power i needed a 3A version but those wouldn’t fit into my lamp.

The techie-stuff is set, let’s get serious with crafts.

Simple method to get outlines of the lamp shade.

The Heatsink is made of 2 parts of 2,5 and 6mm aluminium sheets.
.

In Sketchup it looks like this. RED: Heatsink, black: carbon-fibre. Grey aluminium sheets connecting the bottom part and the power connector (not shown here)

Realization

In step 1 i cutted the heatsink parts relativly roughly with a jigsaw.

To drill the holes (72) for my fake cogwheel i used a dividing head

Dividing head is mounted right behind the chuck of my lathe.

After this „drilling-orgy“ i was ready to cut to the final dimensions.

Most important tool for cutting aluminium is the big one right in the middle. Normal steels from lathes can be mounted in there.

Also the Heatsink looks terrible, my hand was just slightly hurt. A smaller steel got caught between the teeth of the wheel. I wasn’t sure if everything was messed up but i decided to finish the cutting to see if there’s anything worth rescuing.

Looked a lot better then. On this picture i’m just cutting some space for the leds

Scratches look much worse on picture then in reality. The sunk holes are for leds, the normal ones for the mounting of the cf sheet.

Contacts were made from old copper. In opposition to the holders common in most parts of Europe, both contacts are located at the bottom of the bulb. Maybe that is ( or was) more common in the UK or the States. If your wondering why the improvised soldering mount is so messed up… i used a heat gun instead of a soldering iron. Works fine when you don’t have to care about small parts.

After removing glass and wires and all the things inside of bulb i could use the holder for my own project. The new contacts were glued to a small polystyrene sheet and finally everything was sealed with epoxy.

hp-death

Safety note: In this case we deal with 230V~. If you are not absolutely shure what you are doing here – keep your Fingers off this!

I will not take responsibility for any damages that may occur!

All parts together are just about 140g.

Impressionens

Photographing light is not easy but the 300lm on the picture above are enough to work and read for hours.

Conclusion

From an economic point of view this project was totaly bonkers but as long as i don’t have to be a „real“ designer i’ll file this projects under fun. On the Technical side 300lm are the bottom line. If one day compact 2 or 3A drivers are affordable i’ll definitively upgrade my setup. Then i’ll also see if my Heatsink can handle some extra wattage. After 2 or 3 hours i’ve got temps of 40-50°C. Leds still got some air (70°C would be ok, too), but every extra degree shortens their lifetime .

Update 20.7.2008

As i bought the Z-Leds, i’ve been aware the colour temperature was very cold. But that´s what i wanted or better what i thought i wanted. Using this thing for a while now, it became clear that 6500K are a bit too cold for everyday use. For some other projects some Cree Q5 were bought, producing white light with a more warm tone around 5600K.

While experimenting with the new toys i realized, a combination of the two P4 with a single Cree offers a real nice light for working. A few minutes later, a P4 was soldered out and replaced by a Q5. Testing this Setup for a while now, i am sure this comes far more close to the colour range i had in mind before building this spot.

This picture should make the difference pretty claer. It was fotographed with an ordinary sheet of paper hold at distance of approximatley 3cm to the LED’s. The different seizes of the spots result from the angles of the LED’s ( Cree 90°, P4 120°)

Time: 24h

Money: 40€

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in einem Wort: DIY
Selbermachen aus Prinzip, aus Spass oder einfach weil mans kann. Ganz grundsätzlich dreht sich hier alles rund um Elektrotechnik, Mechanik und wie man seine Basteleien hübsch verpackt (aka Design). Für die Naschkatzen gibts die Kategorie "Köstlichkeiten", selbstgemacht ist hier natürlich auch das Essen!

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