Introduction: Electronic All Seasons, All Holidays, LED Earrings
OK, so we are about to make some pretty advanced earrings.
This is NOT a beginner project, and I would recommend those that want to take this on, start with smaller projects and work your skills up to this.
So first.. Things we will need. (PARTS)
(1) Lead Free Solder Paste, I really like the MG brand can purchase here ( Lead Free Solder Paste ) ~$17.00
(2) Atmel AT-Tiny 85 SMD Microprocessors, Digikey had them ATTINY85-20SU-ND $3.06 for 2
(2) CR2032 Batteries, Found virtually anywhere they sell batteries. ~$2.00 for 2
(2) Momentary Tactile Tact Push Button Switch 3 x 4 x 2mm 2 Pin SMD, I got mine off Ebay $0.60 for 2
(2)SPDT Mini SMD Slide Switch Part Number: CUS-12B, Search for "Slide Power Off/On Panel PCB MINI SMD Switch,SPM" on Ebay $0.25 for 2
(2) Battery Holder Clips, found on Digikey.com ( BK-912 ) $0.62 for 2
(14) WS2812B Digital LED Chips SMD, Search Ebay for the part number and you can find TONS. $4.28 for 14
(14) 0805 1uF Ceramic SMD Capcitors, Digikey ( 399-1284-1-ND ) $1.26 for 14
(2) 0805 Resistors SMD 120ohm, Digikey ( 1276-5510-1-ND ) $0.20 for 2
(3) Earring PCB's (You really only need 2 but have to order in 3's) Order your PCB's from ( Here @ Oshpark ) $7.10 for 3 (I made the PCB files in Eagle CAD and uploaded the files to OSH park for easy ordering)
(2) Earring loops for the ears, Got mine at a local Bead Shop $1.00 for the pair
Total Parts Cost: (less the Solder paste you can use again, AND not including shipping for the items)
$20.37 for the PAIR ($10.19 each)
Now TOOLS you will need.
SMD Hot Air Rework Station OR Toaster Over designed or (modded) for Baking SMD parts and boards
SOIC 8 pin SMD Programmer Socket with ISP header (I made my own seen later in the project from this @ Adafruit and This Board) But you can buy them if you like pre-made ready to go. If you think you can do the project but lack the ability to program the ATTiny 85 chips, just reach out to me and I can mail you programmed chips so you can make the project without all the programmers. :)
ISP Programmer of your choice I REALLY like this one HERE (This is also the one seen in the project later on.)
Obviously Some kind of Computer to run Arduino IDE on
And The CODE you will need to upload to the ATTiny 85'sFound HERE
Step 1: Prep Your PCB's With Solder Paste
Let your solder paste sit at room temp for 2 - 3 hours before attempting to use
(Store it in the fridge)
Once warmed to room temp, begin to place SMALL TINY smears of paste on EACH Copper pad as shown on the front of the earring.
It's OK if some of it bridges across pads as it will separate when heated to the correct temp.
Once you have all the pads done on the front side ONLY. You are ready to place parts.
Step 2: Place SMD Parts on Your Paste and Pads
Begin to place the tiny SMD parts on the copper pads on the board.
For the Capacitors and resistors there in no polarity, and it does not matter how they go on as long as each end is on a paste coated pad.
1) Place the Resistor on the Pad Labeled R (1)
2) Then the Capacitors go on on the other small pads (7) in total
3) Last place the WS2812B LED Chips. NOTE these have a tiny indent in once corner of the LED.
Align this with the the folded mark on the board.
Each LED landing spot will only have one of these, MAKE sure the the chip is on correctly.
Failure on ONE LED will cause the entire project to not work at all.
The divots on the LEDs are too small to be seen in these pics, but I assure it's there and lined up with the fold marks on the board. :)
Step 3: Next We Add HEAT to Melt This All Together
Set your Hot Air gun to 340C and I used an air flow speed setting of about 3
And begin to slowly head up each pad, the entire board will need to warm up before any of them will really begin to melt.
Once the solder has melted correctly then move on to the next one.
WATCH out for putting the heat directly on the LED this is BAD.
You want to heat the edges of the LEDs where their Pads are to melt the Solder paste and do what's called reflow.
Check out the video on how to do this correctly, Video
and you can see it all in action much better than the pictures show!
PS NOTE: You can also use a modified toaster oven or a reflow oven, to do this part too instead of the hot air station.
You would simple place the loaded board into the oven and bake it as described in the oven documentation :)
I do not have an oven, and will not cover the oven baking method in this Instrucable :)
Step 4: Programming!!
Load up the Earring code (link in the first page) into the Arduino IDE
Arduino 1.6.3 was current when I wrote this, and that's what's pictured here.
Place your ATTiny 85 chip into the SOIC socket
Plug in the ISP programmer to the SOIC socket and then the connect the ISP programmer to the computers via USB
Make sure you select the correct PROCESSOR (ATTiny 85) and CLOCK (8mhz internal clock) as shown in the pictures.
Then click BURN BOOTLOADER this should be almost instant, it's just going to set the processor fuses for us for our clock and such.
Last click UPLOAD USING PROGRAMMER, your instructions may vary according to your ISP programmer.
Please refer to your programmers instructions on how to upload code if you are not using the same programmer as I do
Should take 30 seconds or so and show "Done Uploading"
Do ALL these steps for BOTH Chips.
They are now programmed and ready to solder to our boards :)
Step 5: Solder Other Side of PCB Now With Parts.
As before, paste each solder pad with paste. Less is more here, if there is a tiny thin coating on the pad it's perfect.
no large blobs, or "drops" of paste...
Then place the devices with tweezers.
Make sure when you place the IC chip you align the O on the chip (in the corner) with the circle O on the board mask. This ensures the IC is not on backwards!!
Once they are all placed, then solder them with the hotair rework station again same settings (340C and #3 air speed).
MAKE sure there are no solder bridges on the IC chip, if there are fix them before continuing on. If this happens you can try to use a soldering iron to break the bridge..
If all looks good then you are ready for a battery TEST!! :)
Step 6: Add the Battery
The CR2032 battery should just slide right in as shown. make sure the smaller circle part of the battery is DOWN.
The + on the battery should be face UP as shown.
You are now ready for your test!
Flip the switch on and see what you get!!
Step 7: How the Button Works Once Turned On
OK the MODE button on the front has 2 functions.
1 of them I forgot to mention in the video.
1) Press it quickly to change the MODE.
This will cycle through all the color modes I programmed (Feel Free to edit it yourself for your own colors when programming)
2) If you press and HOLD it for 1-2 seconds it will adjust the brightness.
They turn on at medium brightness.
If you press and hold, they will go into Highest brightness, press and hold once more and they will go into Lowest brightness, do once again, and you are back to medium brightness.
Check out the video for all the modes and what they look like. Video
Also a quick note I never finished the code completely, I wanted to add an interrupt to the code so the button world be more responsive but just never got around to it yet. So you may need to push the button once or twice to switch modes because it's not always "watching" for a button press. But as you can see in the video it's still works very well even without the interrupt code always watching the button. I may add it sometime in the future and will update this if that happens
Step 8: LAST Step You MADE IT!!!
Simply attach the earring loops to the hole in the top of the PCB, and you are ready to wear them.
(Or give them away as an amazing hand made electronic gift!!! ) :)
These weigh about 6-7 grams which is a completely normal weight for earrings of this size.
The battery will last about 4 hours with all the colors.
Then the blue will begin to fade out thus altering any other colors that rely on blue (Purple, White, Pink, Lighter colors, Pastel colors, etc...)
The Green and Red colors will run for about 12 to 16 hours and begin to slowly get dimmer and dimmer.
The Leds will just slowly fade to off, the processor can run at a much lower voltage than the LEDs so the LEDs will just fade out eventually as the battery dies.
Note: You can also get batteries for as low as $0.16 cents each on Ebay if you do some hunting and buy in bulk. IE(I bought a 100 pack for $16.00 free shipping) so they can be found MUCH cheaper then $1 ea if you look around online.
Hope someone out there can enjoy making these as much as I did creating them from scratch :)
Got questions? Post them up in the comments section....