An interactive butterfly for in your hair!

A friend of mine wants to marry like a butterfly! So she asked me to make an interactive butterfly on a hairpin, to put in it her hair. Is this possible, she asked? Of course this is possible! The biggest problem in hardware was finding a small servomotor, to be fitted on a hairpin.

The other problem in software was programming the ATTINY45 with interrupt and ADC converter (analog PIN) and PWM, for the servomotor. But since I have done that for you (reading and combining codes of others on the internet) you can just upload my code, and make variations.

Then start a production of butterflies and become rich! Because which woman wouldn't be married like a butterfly, there must be an enormous market out there!!!

Step 1: Components

components needed:

a hairpin! (just ask your girlfriend!)

butterfly (you can the ones on the picture at  )

servo motor ( the smaller the better, the smallest I found was at
(There are smaller ones, see the comments!)

ATTINY45 (8 PINS, yes SMD, you can by this at )
3mm LED (or even smaller, in any electronics shop like )
LDR ( Light dependent resistor, under a euro but to be bought everywhere, nothing special)

one resistor of 4.7 kOhm, (small, for combining with the LDR)
some perspex, (for putting the butterfly above the servo motor)
some thread, (to get the movement from the servomotor to the wings)
some wire, for attaching the components
some PCB with copper you can cut with a knife, for mounting the ATTINY45 without EAGLE (although you can do this properly too of course)
batteries (total around 3V), so no extra resistors for the LED's are required
some paint used for models, making the hairpin and components disappear in the lush hair of the bride

Some components I had to buy especially for the butterfly were the glue and the polyester thread. (glue 3 euro, thread 60 cents on a local market)
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contrechoc (author) 1 year ago
Hi pintoc2!
Better late than never...:-)
The LDR is just a cheap one, less than one euro:
range between 2K in light and 1000K or more in the dark
The resistor is a "balance" for the LDR. Normally 2K - 5K, depending a bit on the ambient light you experience.
The chip is running on around 3V, the number of batteries are your choice: the more (in parallel) the longer the butterfly stays alive.
The essence of the circuit is the LDR giving the analog input and the reaction of this signal in the servomotor.
You can try first with a "big" attiny45 on a breadboard, (programmable now with the Arduino IDE), or even an Arduino. LDR and a servo. For me the problem was to get it as small as possible.
ok, hopes this helps!
pintoc22 years ago
I've made several attempts at making this and have yet to get one that works. Has anyone other than the author completed this project and gotten it to work? The author seems un-willing to give any further information.
pintoc22 years ago
You only mention one (1) resistor in all of your instructions yet your photos show two (2) one large one at the top of your circuit board. what is it and what is it connected to. Also your instructions say connect resistor to PB2 and GND yet the schematic shows PB2 and VCC. which one is correct?
pintoc22 years ago
A couple of questions. Does it matter what the rating of the LDR is? and it looks like you are using a total of 8 batteries is that correct or are there only 4?
Very pretty. Just hope nobody tries to be helpful and shoosh the butterfly off your head! ;-O) 5 stars!
ramkrishna3 years ago
Awesome application. How did You program the ATtiny45?.
chicopluma3 years ago
relly cool, you really can trick the people with this
allen3 years ago
Hobbyking has a servo a bit less then half the weight of the one you've got linked. It's design looks like it might work better as well:

Just in case the link doesn't work it's titled "HobbyKing Ultra Micro Servo 1.7g for 3D Flight (Right)".

It comes in right- and left-hand versions so I suppose you'd have to give that some consideration.
contrechoc (author)  allen3 years ago
Thx great, although for this wedding it will be too late...there are minus 9 items in stock! But i''l come back to the link....
cutshopguy3 years ago
Pretty cool.
I'd like to have a go at building this, but with zero background in electronic engineering a lot of the wiring instructions for the ATTINY and so on are gobbledegook. How about a nice, easy-to-follow line diagram and circuit?
I'm sure the lovely bride will look amazing!
contrechoc (author)  cutshopguy3 years ago
I have added the schematics, the wiring should be clear now. Indeed the bride is very happy.
moparman3 years ago
For some fine stiff wire, try some guitar strings.
cjrush10093 years ago
Thats really cool, but (sorry to burst any bubbles) but you can get an aliform monarch butterfly that moves with memory wire and a battery for 20 bucks. While its fun to build something cool there isnt much fun re-inventing wheels.
lbrandstein3 years ago
Awesome!!! Would love to see the final product too. I would totally buy this for $10-15 too, depending on how nice/realistic it looked, FYI...
Not sure I'd categorize hiding fake bugs in the bride's hair as an "enhancement". Certainly better than real bugs, but still pretty gross.

To each his (or her) own...
It's not like someone is going to do that with a centipede or something so there's nothing gross about having a mechanical butterfly in your hair.
devonfletch3 years ago
I found some wire .007" dia, came from SS-wrapped auto hose, very flexible, about 3 lbs breaking strain.

Very handy to have about! Best way to harvest it is cut (w/Dremel) diagonally around the hose, half of the wire comes off in long lengths, half are short (being the ones you cut).

Shop around, I have found some hoses have a slightly bigger dia, and they are quite stiff. Auto wreckers have a selection, and it doesn't matter what condition the hose is in, you throw the rubber away, anyhow.
This looks like a lot a fun! I'd totally wear it.

re muscle wire: it might be something to consider since you're using a small amount and the motion is small and subtle, but it's trickier than you think. We were discussing it on another forum and a colleague mentioned the following traits:

slow: depends on what you define as 'slow'. It's not super fast it's
definitely slower than your average solid state actuator, DC motor or
whatnot. I think it's response time would actually be quite nice for a
garment, but

hot: I haven't touched one yet, but they do get uncomfortably
warm/hot. My understanding is that it's actually the heat itself,
rather than the current that causes the reaction -- the current is
just a way to generate the heat. For his project, he was using about 8" of wire
--He's been told it's not hot enough to burn you, but still..

current: they draw about 2 A. He says his wire was 1500 mils thick,
which perhaps needs a touch more juice than the 1200 mil thick ones we
used to use.

But yah, think about it! You can get starter kits at
You will want the thinnest muscle wire you can find. Properly made, the wings should present nearly no load at all.

Thinner wire means less power/current required, and faster movement. Not that even thin muscle wire is fast.
drawkcab3 years ago
You should consider using muscle wire for this project...would be less bulky and you could get similar movement by building it into the wings.
chakra3 years ago
you did it!!
two years ago my best friend had asked me to make one for her marriage. i couldn't get a break through in automating it.
but you have achieved it!!
ChrysN3 years ago
Cool project!