Introduction: Love Spark

Picture of Love Spark

Love Spark is a heart shaped pendant that blinks an LED every three seconds and that time is based off of a research conducted by Amy Witter at the University of Melbourne concluding that people think of their friends & loved ones, on average, every 3 seconds. So it's not all just a fancy, blinky-blinly pendant. Every time that LED blinks, it reminds you how often you're thought of by the people who love you and that's a special feeling. Also, it's an excellent conversation starter!

Don't think I could have cooked up a better Valentine's day present for her in over a weekend.

Very minimum parts used, programmed using Arduino, the code looks simpler than Blink!

Parts required:

1. ATtiny13 (replaceable with a Tiny25/45/85)
2. Red SMD LED (1206/0805)
3. 3V button cell (1220/1225)
4. Cell holder (I made it myself)
5. Dual layer copper clad (preferably fiberglass)
6. SMD STDP switch (KPS-1290)
7. Some craft skills + patience
8. A valentine
9. Lots of love

The last three parts are priceless, the rest cost me roughly 300 INR (US$5)

Step 1: Cutting the PCB

Picture of Cutting the PCB

1. Print the template, pick a desirable pendant size and cut it out
2. Trace the board outline from the cutout
3. Cut out the board with a fine hacksaw or a wire saw
4. Finish off the outline into nice and rounded edges with some files.

Step 2: Etching the PCB

Picture of Etching the PCB

I masked the PCB using toner transfer method on one side and permanent marker on the other side and etched using Ferric Chloride solution.

You can find the PCB template in the Download link on the last step, download it and laser print it. For the rest of the how-to, there are tons of articles on the internet and nice instructables on how to etch PCBs at home, most of those articles do a better job of explaining the process than I ever could.

This Two sided PCB using toner method by jmengel does a good job at explaining too.

Step 3: Finishing Touches

Picture of Finishing Touches

I'm not a big fan of the yellowish color of etched PCBs, I did some searching on how to color home made PCBs painlessly and came across this nice article. He uses fabric dye, given my laziness, I used some black hair dye, boiled the PCB in the dye-water mix for about 10 mins and the PCB was transformed!

Make sure your PCB traces are tinned before you dunk it in the hot dye mix.

Program the ATtiny, solder all components and you're good to go!

This is my third prototype. The first one, I tried to etch one side without masking the other side of the PCB and you know, there was noting left of it. The second one, I messed up the switch circuit and soldered the Tiny wrong way, really really stupid mistakes. The third one, the most beautiful etch in my DIY history, it was all worth it.

In all, It cost me four LEDs, three microcontrollers, three switches, FeCl2 stains on my shirt and a weekend hidden away in my workroom, she better like it!

In case you're wondering why cute hair. ;)


And for all you lazy, impatient and non-hackers, Kitables is making a Love Spark DIY kit that you can buy from here.


DecinatyP (author)2016-07-10

... would it be possible to program the blinking to do 5,2,4,2,4,4,2,3,3,1,3,4,5,1,1,5

OneSharpAce (author)DecinatyP2016-12-11

Yeah, the micro processor in it definitely has the same to save a program to blink custom patterns. You just need to learn how to program for it. There are plenty of tutorials for it.

samzie292 (author)2016-06-21

How did you program the Atiny ic?

Modifier made it! (author)2016-03-01

I named it my FRANKEN-HEART

This was my first soldering attempt on a printed circuit board (I just have experience with car audio cables). The image speaks for itself when I say I need more practice to make it as clean as AJ did in this post. It intermittently lights up as I did not know how to effectively get the battery power through the holes in the board. i eventually had to use hot glue to hold it together.... :(

I followed the instructions on dying the PCB board with black fabric dye, but after 30 mins, it only got to this brown, aged color that I didn't mind.

I added a magnetic clasp and a small 3v CR1225 battery

Thank you for the idea and the motivation to finally start programming Integrated Circuit chips and to start soldering circuit boards!

Next will be a Raspberry Pi 3 or an Arduino Uno :)

Aj Creations (author)Modifier2016-05-01

Looks really cool, considering its your first PCB project. Soldering aesthetics comes with practice and patience, you don't have to sweat it. Having good equipment will definetly help, but once you've developed the skills, even a blunt knife can do the damage. Although, a good solder iron with an appropriate tip, rosin core solder and good use of flux, a pair of forceps and some solder wick are pretty essential in any typical circuit soldering attempt. I suggest you check out videos on SMD hand soldering so I you pickup skills faster. good luck!

samzie292 (author)2016-05-01

how were you able to program the IC? I can do on normal IC using arduino uno but how did you manage on SOIC?

Aj Creations (author)samzie2922016-05-01

I soldered the microcontroller on to the PCB footprint and then soldered some wires to the ISP pins to burn the code, then desoldered the wires. check the pictures.

anay97 (author)2015-10-14

Hey, it's a nice project... I was thinking, instead of the heart made from metal I could use something else right? I'm 18( from Mumbai), so I don't really have a hacksaw at home. Will that work?

Aj Creations (author)anay972015-10-14

My whole idea is framed around the PCB concept. The heart is cut from a blank fiberglass copper clad and the circuit is etched in it.
You could definitely come up with something more different and creative than this, do share your ideas!

anay97 (author)Aj Creations2015-10-15

How did you program the atTiny??? Which arduino board did you buy

Modifier (author)anay972016-03-01

I used this Tiny AVR Programmer:

Aj Creations (author)anay972015-10-15

I used a USBasp. You can use a Uno or Mega too.

anay97 (author)Aj Creations2015-10-18

Which is the cheapest one?? Also, where do you buy these things(usbasp, attiny, etc)?? Please be kind enough to explain.. Do you get these things on amazon(link would be appreciated). Thanks alot. Really nice project. My mom's bday is coming up. Trying to make her

Aj Creations (author)anay972015-11-01

I bought the ATtiny13 and the switch from AliExpress since they weren't available locally, they took a little over a month to get to me.
The copper clad board, USBasp and the cell were bought locally, the same is available and can be bought on eBay India. Although, the local market in my experience is a slight bit cheaper.

jnavarro15 (author)2016-01-12

nice project !! i'd like to do this one for valentines soon.. but the links doesn't work..

if you could, will you email me the files? thanks.. ...

samzie292 (author)2015-05-09

How did you do the coin battery holder? I'm having difficulty with that section

Aj Creations (author)samzie2922015-05-10

I just bent a piece of nickel plated copper sheet to hold the cell in place and soldered it down. give it some concave so it maintains tension. check the images.

Aj Creations (author)2015-03-31

Awesome, looks neat!
What dye are you using?
I'd love to see the finished heart.

OneSharpAce (author)Aj Creations2015-03-31

I'm using a light green RIT dye, I put a resistor to limit the current to the bare minimum need for the led. It will still be visible but not as bright as full power. I really only used it for current limiting to save power.

Aj Creations (author)OneSharpAce2015-04-01

Well, using a resistor to limit the current isn't going to save you power, as far as I know. Because resistors dissipate the extra current out as heat, you'd rather use that extra current to blink the LED brighter.

Incorporating PWM in the code will save you power while reducing brightness. I blink my LED every 3s and for an interval of ~5mS, so no need for PWM, draws minimum current already.

Also, I've set the ATtiny clock speed to about 128KHz, as per the Tiny13 datasheet, it should draw less than 10uA @ <2.7v operating voltage on this setting.

OneSharpAce (author)Aj Creations2015-04-01

I have mine clocked at 128KHz as well. I also had a friend show me how to incorporate in the watchdog timer to save more power.

Aj Creations (author)OneSharpAce2015-04-02

Cool, share some pictures when you're done putting together your spark! :)

focheezy817 (author)2015-03-24

From what I can tell on the template, the attiny 13 will not fit. I haven't tried it just yet, but the "legs" of the chip do not fit within the black lines on the template that it was supposed to. I don't have the extra copper to mess up, and I don't want to waste the time as her birthday is in a week

focheezy817 (author)focheezy8172015-03-25

Also, how did you get the attiny to be flat like that? Did you cut holes in the copper and put the pins in, or did you cut the pins down to the size they needed to be?

Veening (author)focheezy8172015-03-27

There are 2 versions of each ATtiny, a through hole variant (probably the version you have) and a surface mounted (SMD) variant which he uses. The same chip in a different package.

focheezy817 (author)Veening2015-03-29

So would I have to clip off the legs of the chip, or do I have to order a new one?

Aj Creations (author)focheezy8172015-04-01

The SMD package that I have used has smaller pitch compared to the DIP ATtiny you plan to use, so clipping the legs off isn't really going to help. You need a bigger and wider IC footprint for that to work.

Veening (author)focheezy8172015-03-29

Both would work but the latter would probably give a nicer result.

Aj Creations (author)focheezy8172015-03-31

It's the surface mount version, 8pin SoIC package.

sabas1080 (author)2015-02-10

Link Download dont' work :(

aditya111 (author)sabas10802015-03-19

hey brother can u email the downloaded file to plzz me by sending that on my e-mail id... i'll be very thankful to you..

Aj Creations (author)aditya1112015-03-31

Sent, sorry for the delay!

Aj Creations (author)sabas10802015-02-12

Sorry! Fixed.

sabas1080 (author)Aj Creations2015-03-22

Thanks :D

OneSharpAce (author)2015-03-29

I have made a few changes, I added a resistor and I increased the size to use a CR2032. With my code it should last about 9 months on a battery.

Aj Creations (author)OneSharpAce2015-03-31

Just curious why you put the resistor?
I had thought of the resistor too, but considering it being there to only limit current and my tiny cell being incapable of supplying such currents of such magnitude and the code being writtent to blink the LED for only about 5mS, it seemed unnecessary to me.

Wished I could have gone for a 2025 or 2016, but I wanted it to be a small. She's short too. Lol

aditya111 (author)2015-03-19

from where you get that heart shaped pcb???

Aj Creations (author)aditya1112015-03-30

I crafted a dual layer copper clad into a heart shape. check pictures.

chandubandara (author)2015-02-16

this is awesome as always my bro!!! cheers!

Azuria (author)2015-02-15

Very nice... Unfortunately i first stumbled on this today.
But a birthday is coming up. ;-)

Do you have the original design files? I would like to edit it a bit :)

Thanks mate.

Aj Creations (author)Azuria2015-02-15

The original design file is in the download folder. Let me know if you need anything more.

Azuria (author)2015-02-15

I would like to have a note about the study by Amy Witter... But when i google it, all i find is a lot of links for this article right here. ;-)
Do you know where i can find it?

Aj Creations (author)Azuria2015-02-15

yup, I couldn't find it online too. I read it in an Indian kids magazine called Facts Foreman, I'll try to get a snapshot of the mag and share it on here.

BrownDogGadgets (author)2015-02-11

Kudo! I've always wanted to make a necklace like that! Nice job with the toner transfer PCB.

Yup, thank you!

I keep wanting to make one up using a Tiny85 (I have a bunch around) and a through hole LED. Make it a simple soldering kit for kids or whatnot. I'll have to do that this summer.

SoLongSidekick (author)2015-02-14

Am I missing something? I don't see a PCB layout for the back.

Never mind, I see you just free-handed the back.

Yes, sorry my mistake it isn't mentioned.

mpulliam1 (author)2015-02-15

"Simple, elegant" - that is a hard thing to achieve on purpose. You did it.

Up Voted.

About This Instructable




Bio: 22 . Mechatronics Engineer . Hopeless Realist
More by Aj Creations:Love SparkAdding Auto-Reset Pin to PL2303 based Serial-USB ModulesDIY- xESC Adapter [ATtiny version]
Add instructable to: