Instructables
This instructable is about making stars shine brightly. A while ago, it was also about making Christmas trees without cutting down trees. These LED Christmas trees have an Instructable of their own now. They're still in the videoclip, though.

If you can solder a little, you can make LED stars. The stars can be made 6 to 10 cm wide and use a 9 Volt battery as a pedestal.
If you want to easily change batteries, take a look at step 5. The star can be mounted on a 9 Volt battery clip...

No video playing? Have a look at it here...

So get your soldering iron, grab your LEDs, find some batteries and kick off the christmas decorating season.

If you're uncertain about your soldering skills: Start with making the star. It's easy. You can do it. Really. Trust me.

Still in doubt whether you should make the star or not? Here's the one decisive reason you were waiting for:
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The first three Makers who post a picture of their self-made star in the comments get a 3 months Pro Membership gift code from me.
An additional one year Pro Membership gift code goes to the maker of the funniest / loveliest / greatest picture that involves a LED star :-)

december 17th: 
lmijacevic gets the first of three 3 Months Pro Membership codes!
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Hi Ynze,

I'm going to make some, but can you tell me how long the Conrad Zinc Carbon batteries typically last on a tree?
ynze (author)  masynmachien1 year ago
I just checked: Zin-carbon batteries capacity is about 400 mAh, alkaline batteries do a little better: 565 mAh. With a 120 Ohm resistor, a star should last about 5-6 hours on a zinc carbon battery. I feel a need to mount the stars on a 9 Volt battery clip...
ynze (author)  masynmachien1 year ago
Consider making *blinking* stars :-) The video is in the intro, the LED-specs are in step 1...
ynze (author)  masynmachien1 year ago
Uuuuhhhmmmm, many hours, esp when you add a 120 Ohm resistor. The trees I made still work on the original battery. Could you post a pic of the finished trees?

Y.
MoonDocker10 months ago
Great Idea! I made up a bunch of these to hand out for Christmas. I found out that if the 9 volt battery is not up to full charge it will only light up 3 or 4 LEDs. I also had a few LEDs that were more than 2 volts and you could not light 5 up with a 9 volt battery.
Thanks for the idea.
mischka1 year ago
Yesterday I made one with my 6yo nephew. Really cool project for kids to learn soldering!
pjuica1 year ago
nice!!!
robochick1 year ago
Incredibly adorable!
daboys1 year ago
Don't you need to have resistors before the leds?
ynze (author)  daboys1 year ago
It'a not necessary when you stick to 5 red leds. I left them out to keep the making of The stars as easy as possible. You can add a 120 Ohm resistor to spare battery live and protect the LEDs. I did that in the final step...
I managed to make this two somehow, I think they're pretty but strangely they work good only on 15V power supply. I don't know why... Not much...Top LED on the tree is changing color from red to blue. used blinking LED in other tree. Yellow and blue LEDs aswell.
I used old univrsal laptop charger for supplying.
My camera is bad,sorry for that.
Thank's a lot for this :D
Slika316.jpgSlika317.jpgSlika318.jpg
ynze (author)  DoctorLazar1 year ago
I like the tree A LOT! I think your circuit is a little different than mine, looking at your pictures I think you connected all the leds in series (in the same "loop"). For the star, that works fine. To power the tree with a 9V battery, you need to make two groups of three leds in series. Like the circuit in step 2 over here: http://www.instructables.com/id/Make-a-LED-Christmas-tree-without-the-tree/

Anyway, your 3 month pro-membership is well deserved! Great job, thanks for posting!
ynze (author)  ynze1 year ago
Here's the christmas tree circuit...
LED-Xmas-stars-and-tree-24.jpg
It's working great now, thank you! I just have to ask, you will it work if I replace red LED with blinking LED, will the whole tree blink?
ynze (author)  DoctorLazar1 year ago
Your tree: Yes :-)
My tree: no :-(

Give it a try!
I tried... Didn't work :-/
ynze (author)  DoctorLazar1 year ago
No light at all? Or blinking faintly?
I'm going to make these :D
ynze (author)  emilyvanleemput1 year ago
Oh please do! And post a picture when you're done, pleeeeeaaaaaasssssseeee??? :-)
wa7jos1 year ago
Carefully disassemble a dead 9V battery (everybody has plenty of those, right?) and salvage the connector.
Solder the LED's to that (instead of directly to the battery).
That gives you a way to turn it off, and to replace the battery when discharged.
ynze (author)  wa7jos1 year ago
I used a battery clip. It's in step 5.
ynze (author)  wa7jos1 year ago
...but how to connect the salvaged connectors to the battery?
wa7jos ynze1 year ago
A battery clip is just the mirror image of the battery top. A salvaged battery top snaps right onto a battery.
ynze (author)  wa7jos1 year ago
Owwwwwwwwwwwwww, I overlooked that. I considered hacking a batteryclip, but this is the no-budget solution :-)

Thnx!
Here's my first build. Because I was planning to use these as Christmas decoration at work I needed them to last at least a week. While looking for parts on the Conrad site I saw a terribly kitschy USB bowered miniature Christmas decoration and thought: That's it! I'm going to use USB-ports of the many computers available at work. I made trees with pairs of green LEDs in series an three of those pairs in parallel to make a tree (see the schematic). I started with a red LED on top, with a resitor in series. Then I replaced it with a colour changing LED. Those LEDs can be powered on 5V directly, but I kept the resistor to trim the brightness down, matching the brightness better with the green LEDs. The USB connector is made with a piece of stripboard. I added a fast 500mA fuse to reassure our IT-department, as rumors go that the USB short circuit protection on PC's isn't very reliable. Where leads that should not contact come close to each other I added a drop of hot melt glue as a insulating spacer.
IMG_5674.jpgUSBtree.jpeg
ynze (author)  masynmachien1 year ago
Coooooooooooooooool! Thanks for the post! The color changing LED is a nice treat!

You just got yourself a 3 month pro-membership :-)
wobbler1 year ago
Great idea and I really like how the wires make the shape, no messing about with circuit boards. Although these obviously work, I would always put a current limiting resistor in to a circuit like this. I'd suggest 47-220ohms should be ok. This will limit the current and they should therefore run for longer, but its main function is to stop your LEDs getting burnt out by too high a current. However, these 9v batteries have a relatively high internal resistance so the cells themselves act as current limiters, esp. on old batteries. Iif you replaced the battery with a 9v PSU though, it could be dodgy. I noticed you mentioned a 120ohm resistor in one of your replies, which is a good idea.
Merry Christmas! *<||;o)>
Very nice indeed! Borrowing an idea from the Evil Mad Scientists site (http://www.evilmadscientist.com/2012/flicker-leds/), replacing one of the star's LED's with a flickering LED should make the whole thing flash - though you'd obviously have to keep an eye on voltages,

And I'm not sure quite how you might fit one into the tree - you'd probably only want the top 'star' LED flashing, I assume, so you might end up needing resistors...

Personally, I find it almost impossible no to leave a soldering iron on too long, and wouldn't want to overheat a battery, so I'd open up an old 'snap connector' and solder the copper wire to THAT.
ynze (author)  karlpinturr1 year ago
Oww, that blinking LED is a nice idea! Worth a try...
janw ynze1 year ago
Great project Ynze. I once did build a Valentines Heart with 1 blinking led in the middel. It's a great way to make the whole thing blink.
ynze (author)  janw1 year ago
Thanks! Today, I bought myself two blinking LEDs! It's pakjesavond, you know :-)
janw ynze1 year ago
Wow, I bet that that was the most expensive present ever :)
ynze (author)  janw1 year ago
...but boy, did I have FUN with that blinking LED, for just 95 cents :-)
janw ynze1 year ago
That's not cheap for a blinking LED. I pay only 0.33 for a blue one and that is the most expensive that they have. For only 0.21 you hasve one that flashes alternating between blue and red.

Have a look at leds-buy.nl
ynze (author)  karlpinturr1 year ago
IT WORKS!! One blinking LED in series with 4 low current LEDs do the Christmas Star Trick! Despite of specs that very clearly indicate that it's "impossible" :-)

I made a video, it's in the intro...
Glad to help - it looks good.

One thing I'm not clear on - why did you go for 'low current' LED's? I've looked again at the EvilMadScientist page, and can't find any such reference. Is it jus to prolong battery life?
ynze (author)  karlpinturr1 year ago
The problem is the voltage drop of the LEDs. The battery provides 9 Volts, and the leds are in series. So the battery's voltage will be -sort of- equally divided over the LEDs in the circuit. The blinking LED has, according to the specs, a voltage drop of 3V. The low current LEDs have a voltage drop of 1.8 V...

So, in theory, the star *shouldn't work* : 4 x 1.8 Volts (low current leds) + 3 Volt (blinking LED) = 10.2 Volts. That's about 1 Volt higher than the 9 Volt available :-s

I decided, against the odds, to give it a try anyway. To have some chance for success, I bought low current LEDs (with the lowest voltage-drop) I could get.

... and, to my surprise, it worked!
killbox ynze1 year ago
yah, most blinking led's will work down to just about 2v, they just get dimmer.
Ah! Thanks for that.

I assume it works because all the voltages are, essentially, 'nominal' - that is, the battery can't give exactly 9 volts, so is manufctured to give a little more, and the LED's can be overdriven by an amount before you shorten their lives considerably - and everything just happens to match up...
racoontnn1 year ago
Wonderful, amazingly simple and effective!
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