Instructables

Solar Powered SKULL Blinky LED Pendant Jewelry

Picture of Solar Powered SKULL Blinky LED Pendant Jewelry
P1010351.JPG
snapshots9.jpg
This instructable is for solar powered Skull with sinister red LED eyes.  It measures about 2 1/2" by 1 3/8", including the USB tab.  It has one hole through the top of the board, making hanging easy.  Wear it as a necklace, earrings, keychain, bond on a pin, or hang it in a window.  The possibilities are up to you, and we'd love to see what you do with them. 

The schematic and parts list are included.  You are welcome to wire up your own, copying is the sincerest form of flattery.  We also have the kit available in our Etsy Store.

If you have soldered projects before, this will be easy.  There are only 19 pieces to solder onto the board, and all are through hole.  Depending on your soldering savvy it may take anywhere from 30 to 45 min.  Watch it in action here!
So lets begin!
 
Remove these adsRemove these ads by Signing Up

Step 1: Tools

Here's what you need:

A soldering iron
Solder
Diagonal cutters

Helping hands and needle nose pliers are optional, but helpful.

Step 2: Schematic and Parts

Picture of Schematic and Parts
P1090383.JPG
Schematic is above.

Parts list is below.

C1 - 47uF ceramic capacitor  (medium blue one)
C3 -10uF ceramic capacitor  (little blue one)
C5 - 0.033uF Timing capacitor (TINY tan one)
U1 - MCP6542 dual micro-amp comparitor
SC1 through SC6 - BPW34 photo-diode
R6 - 330ohm resistor
R1, R3, R4, R5 - 10M resistor
D1 and D2 - amber LED to blink
Switch - SPDT switch 3-pin 0.1 spaced
C2 - 0.03F coin super cap
MoonDocker4 months ago
Thanks for the instructable. This was a wonderful christmas gift for my wife. Works and looks great! I will be ordering some of the other items you have in your store. Simple and easy to put together. I did hot glue a piece of fabric to the back of the skull. Maybe you could include a piece of felt?
lumenjewelry (author)  MoonDocker4 months ago
Thanks, I'm glad you enjoyed it. The felt or cloth on the back is a really good suggestion. We will add that to our instructables and look into adding it to the kits.
masood12346 months ago
Sorry correction to my last question, I meant replacing C3 not C2 with a 10uF tantalum.
lumenjewelry (author)  masood12346 months ago
I wouldn't recommend using a Tantalum cap for C3. The polarity of C3 changes with each flash and Tantalum caps tend to explode if reverse charged. Aluminum electrolytic caps are less volatile, so I'd be willing to try a 10-15 volt 10uF aluminum cap as C3. I'd expect an aluminum cap to work for a few months at least. Lastly eyes have a logarithmic response to brightness, so using a 1uF to 4.7uF ceramic cap for C3 only dims the flashes to about 1/3 as bright. (using a smaller C3 would also let you shrink C5 for faster flashing without hurting run time)
masood12346 months ago
Further question about the hard to find capacitors. If I were to replace C1 with a 47uF tantalum I take it the polarity would be same orientation as the supercap, C2. What about replacing C2, also with a 10uF tantalum, how would its polarity go?
masood12346 months ago
I'm Interested in making this project but I cant source the 47uf fixed ceramic capacitor. Where are these available from. Would a tantalum substitution work
lumenjewelry (author)  masood12346 months ago
Digikey stocks some TDK capacitors in this size.  445-8540-ND (or at Mouser 810-FK26X5R0J476M )  A Tantalum cap or two 22uF ceramic caps in parallel would also work fine.  The circuit isn't too picky about what is used for C1 as long as it's a much higher value than C3. 
pandyaketan9 months ago
Firstly, a very fine & compact project!
5***** !
Now:
This seems more of a usb powered led project than a solar one.
What is the "solar only" circuit?? (No USB port or USB CHARGING of any kind!)
Would this "solar only" circuit just "blink" or throw some light also??!
Would like to make a "solar only" circuit - using photodiodes/ldrs, leds, and capacitors (hopefully, no resistors since they are a waste!!)

reg
ketan
lumenjewelry (author)  pandyaketan9 months ago
For "solar only" just leave off R6 and the usb-connector.

With the above mods, the circuit would still just "blink". To "throw some light" you either have to accept a much shorter run time, or use a much larger solar array and storage system. (and re-design the circuit to use more power)

If you want the simplest "solar only" project that glows, see our 3 piece solar powered LED instructable.  (which will scale up just fine with different parts)  For anything fancier, you're going to need to use a few resistors in your solar project as part of a timing circuit (R1, R3, R4, R5) or as current limiters (R6). 
I made a 555 timer led bracelet, I wanted to use a super cap but I cant find where to buy them, is there any online shops you would recommend?
https://www.facebook.com/photo.php?v=10200163798636986&set=vb.223939090958358&type=2&theater
lumenjewelry (author)  out-of-the-box9 months ago
I usually buy stuff from www.digikey.com or www.mouser.com.  They ship fast and let you easily search by component electrical parameters. 

I'd suggest using this super-cap or this super-cap for your bracelet.  They should run it for 5-10 minutes on a charge.  For better run time I'd also suggest switching to a low power 555 timer like the TS555IN.  With a TS555IN, high brightness LEDs, and some power optimization you should be able to get your bracelet to run for 1/2 to 1 hour on a 1F super-cap.  You could also pick up a usb-b connector as a convenient charge port. 
im using the tlc 555 timer, runs on a minimal of 2 volts (might be 4) the timmer is perfect i just use one small battery. Thanks for the links! Ill look into it
i love this! If i had extra cash I would buy your kit. I love the way the componets are laid out, adds detait to the skull. This is a future purchase!
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!