Introduction: A Fancy LED Reading Lamp Made From a Spray-can
This is my first publishing here, also don t hesitate to ask me, if my try to write it in english makes no sense at some point ;)
Another time as my deodorant spray went empty i wondered what could i do with this nice brushed aluminum can instead of throw it into recycling bag. My thoughts where inspired by the creative guys in Africa who make model-cars out of used food cans. Also it s an experiment to build something by using most of the can.
The shape of a spray can has two advantages to build a LED Lamp. The hollow bottom will become a good reflector and the cone top of the can the pod.
But now let's collect the materials:
- A Spray can - EMPTY - Real Empty !
- 4 Power LED s : NICHIA 5mm Power LED white 28lm NSDW570GS-K1
Each LED costs ~ 1,50 Euros. I ordered mine at lumitronix.de
These nice pieces are the brightest an most efficient on the market. Also the light beam has 140 degrees. Most 5 mm power LEDs have 15- 20 deg. I have chosen white light color for reading light. So the type shown above are white ones. if you prefer others you maybe have to recalculate the power circuit.
- A Resistant with ~ 15 Ohms / 0,5 Watts
- A Wall socket switching mode power supply with max 9 Volts (min 200mA)
Don t buy or use old fashioned heavy metal transformer supplies. The PS is most of the time in the wall socket, because the lamp is switched on the output of the PS. The standby power use of switching mode supplies is much better than the transformer heaters.
If you use a supply with voltage selector you can dim the lamp in some steps, in case the beam disturbs your wife/girlfriend/husband/friend/pet/neighbor who try to sleep while you read.
Most switchable power supplies will have a 12 V Position too.
12 V will destroy the LEDs in my designed circuit. Make sure that you nut switch it to this. Maybe block the position with a tape.
- some (in my case metric) screws with 3 and 4 mm ,washers and nuts.
- A Wood screw, and depended of your wall a wall plug ;)
- some faucet washers - for example those where you buy to repair a dripping faucet. Other rubber washers will do it too.
- A wire switch or a piece of cable with switch. You can use on from a old lamp, but first of all cut the wall plug !
- some heat shrink tube to insulate the soldered cables
- A piece of wood a bit larger then the can's diameter, ~ 2 cm thick.
- at least time, a bit steel wool and aluminum polish.
Step 1: Let S Prepare the Can
First i recommend after every step with tin work to burr holes after drilling and file every edge after cutting. Sheet metal turns easy into a sharp knife.
Due th reason that the can material is very thin, you can prepare the drill holes with a puncher to easy fix the drill. Also i drilled the holes always in two steps. First a small drill, then the needed diameter.
The measures will vary depend the can you like to use. Also i will disclaim to give instructions where to cut the can and put the holes. Just look at the pictures and put it where you think its the best.
I made most steps with a drill stand, a step table and my lathe.
Sure this is not necessary, if you like and can handle it, you can do it with common tools. At least mechanical skills and the save handling of a soldering iron is recommended.
After you made sure the can is empty remove the cap. Cut the bottom about the quarter part of the can. Remove the valve from the top and the little hose from inside. Keep the parts for later use. (Yeah, everything will be recycled!)
Drill one 5mm (better 4,9mm) hole in the center and three in 120 degree steps in a circle in the hollow bottom.
Take care to drill the holes in the circle in the angle that the bottom has at the drilling point. Otherwise the holes will become egg-shaped. If you not ow drills in 0,1 mm steps, drill smaller and file the holes wit a round file until the LEDs fits hard.
If you like you can mill or cut some arcs or other shapes at the back side of the LED Unit. At least polish the can bottom hollow space with steel wool and then with aluminum polish to get a shiny reflector.
Now cut another ring from the rest of the can that is thick enough as bow to carry the LED unit.
Cut the separated ring to get a stripe. Drill three holes as shown in it.
Now drill a hole in the cone part of the top with the diameter of the little hose you kept by unmount the parts. The lill hose will sticked through and carry the cables to the LED unit..
Drill another one at the bottom for leading the supply cable through. I ' v made a shell out of a part of the valve to save the cable from the sharp tin. Shown on last picture.
Step 2: Put It Together
Put a screw from inside the can out to the top. Place a screw washer, a faucet washer, the bow another faucet washer, another screw washer on it. Fix it with a nut and a locknut that you can move the bow by hand.
The faucet washers are used as breaks to keep it in position and prevent from self adjusting.
Now connect the LED Unit (twice) to the bow like the bow is fixed to the top of the can.
Saw or turn by lathe a disk out of the wood that fits strongly in the can. Drill a smaller hole then the wood screw in the center and turn the wood screw in.
After cleaning the reflector and other parts from polish and aluminum dust, stick the LEDs in the reflector.
Stick the little hose in the hole at the cone top that it s long enough to reach the LED unit. You can heat it up a little with a lighter and shape it to a light arc pointing into the LED unit. Take care that the warm hose is not smashed while bending.
Step 3: Work for the Electrican in You
WARNING: the lamp is designed to work with low voltage. The dangerous part is banned between wall socket and power supply.
DON T BULD IN 220V / 110 V LIGHT BULBS !!!! NEVER DIRECT ENTRY HIGH VOLTAGE IN THE LAMP !!
It would be good if you ve soldered LEDs and electronic parts before and understand the basics of an electrical circuit ;) But feel free to ask me if you don t understand something.
To make the project not too expensive i decided to use a resistant to fit the LEDs current.
Sure a constant current unit pcb, and as high end a buck mode one is the Rolls Royce of LED driving. But in this low power regions and the freedom of combining the LEDs close to the supply voltage, a resistant will do it too.
Also the resistant will heat up your bedroom in strong winter days a bit, in case of less activities in there ;)
OK, each NICHIA power LED is driven in my case with 70 mA @ 3,4 Volts. To reach this i have connected respectively two LEDs serial and the serial units parallel. The 15 Ohm resistant is connected between the "+" and the circuit.
two serial LEDs with 3,4 V have 6,8 V and 70mA. Two serial units parallel 6,4 V and 140 mA. Driven by 9 Volt you have to destroy 2,2 Volts by the resistant.
A final test has shown that switch back to 7 Volts at the supply is bright enough to read.
Now heat up the soldering iron and solder the LEDs as described, take care for the polarity.
Put two tiny cables in the hose from the bottom to the LED unit. Solder each one to the common Anode (+) and Cathode (-) leg. Solder the other ends "-" to the supply cable (with the switch) and the "+" cable to the resistant and then to the supply cable.
Cover the uninsulated cables and the resistant with heat shrink tube.
Connect the other End of the cord (with the switch) with the power supply.
NOT WITH A WALL PLUG DIRECTLY !!!!!
Now you can make your first test run! Don t look straight into the LED s. They are bright as hell!!
Step 4: The Finish
After the test run was a full success you can go to the last step:
Put the wood disc with the screw pointing to the outside in the open bottom of the can. Take care that you not cut your fingers off when the disc is slipping in quickly. If you like yo can fix the disc from outside with tiny wood screws.
Now throw the whole lamp with the screw in a wall plug, or if you have a wood house directly into the wall.
Push the switch and start to read...
after finishing and having it some days in test run i' d like to share my results of the test run with you and what i think what could made better.
1. Placing a tube on the reflector that prevents the light from beaming to the space outside of the book. Not every time my wife and i read to the same time. If she wants to sleep, the light falls to a part on her bed and she could not sleep then.
2. Making the bow more stable by folding the stripe in the middle to get double thickness of the metal.
3. figure out a better solution to lead the cable from the bottom to the LED unit. Ok, the cable are thin and flexible, but it' s not designed to adjust the reflector hundred times a day. Someday a soldering spot or a cable will break.
4. The wire switch problem.
Sure a wire switch is handy to use and easy to find in the dark. A disadvantage i figured out, on another LED lamps too, is a electrical Problem.
The light starts after a long time in use to flicker. The reason is the passing resistant over the switch contacts. If these resistants reach some milli Ohm the Lamp flickers, because of losing some mV at the unwanted resistant is fatal in the light result, at a lamp driven only with 9 Volts.
These switches are build to switch loads with 110/220 Volts. A little passing resistant is there no problem. Also the LEDs are driven by DC and DC always has a higher tendency to build a light arc while switching of. These made the contacts earlier worn out.
At least a miniature switch designed for low voltage use, maybe with gold plated contacts, will be a better solution.
5. Syncing the drill holes from the LED unit which is connected with the bow with those of the LEDs. So that the LEDs look not asymmetric in front view.