Picture of Animatronic Cat Ears
  I saw the demo video for the neurowear "necomimi" brain controlled cat ears and I thought they were pretty awesome.  I'm just starting to learn electronics and I thought a fun project to start out would be making my own version.  Sadly, I don't think I'm adept enough yet to take on making my own EEG and I don't think the EEG's that are available are very reasonably priced, so I settled for having a button input to control the cat ears.

  I wanted to build something that wasn't too expensive and was easy enough to be done in a sitting or two.  I picked out some cheap servo motors, some craft supplies, spent a weekend or two developing code to control the servo's from a microcontroller and after much trial and error, I built some kitty ears that I think are pretty decent.

  Here's a video of my lovely assistant using the Kitty Ears:

Step 1: Tools and materials

  Safety glasses
  Face mask
  Hot glue gun (and hot glue): I picked one up for under $5 at a local Michaels Craft store.
  Dremel:  $18.99 at Harbor Freight Tools (http://www.harborfreight.com/professional-4-speed-rotary-tool-kit-40457.html)
  Drill: $18.99 at Harbor Freight Tools (http://www.harborfreight.com/3-8-eighth-inch-variable-speed-reversible-drill-3670.html)
  AVR Programmer: USBtinyISP AVR Programmer Kit from adafruit.com $22.00 (http://www.adafruit.com/products/46)
  Soldering Iron
  Wire strippers
  Wire cutters
  Flex tubing: $2.88 from WalMart

  ATTiny13: $1.09 from mouser.com (http://www.mouser.com/ProductDetail/Atmel/ATtiny13V-10PU/?qs=sGAEpiMZZMvu0Nwh4cA1wUVlLgw9m2DPt6IffusRY5Y%3d)
  4x micro servo motors (hxt900 compatible): I found a few different places to get these.  I've had good luck with hobbyking, but there's also dealextreme.com, suntek.com and ebay.
  Proto Board:  $3.19 from Radio Shack (http://www.radioshack.com/product/index.jsp?productId=2102846#)
  Wire: Black and Red are good choices for colors
  Pushbutton:  I like the sub mini pc mount pushbuttons (4 for $1.00) (http://www.allelectronics.com/make-a-store/item/PB-126/SUB-MINI-PC-MOUNT-PUSHBUTTON/1.html)
  1k resistor: (brown black red)
  LiPo battery: Anything that will be able to supply 3A worth of current.  Here's a good choice from hobbyking for $5.33:
  LiPo battery charger:  You might want to shop around on ebay, but Hobby King sells one that I've used and seems to do the job here: http://www.hobbyking.com/hobbyking/store/__8247__Turnigy_2S_3S_Balance_Charger_Direct_110_240v_Input.html ($11.44)
  DC-DC regulator: $4.90 from hobby king (http://www.hobbyking.com/hobbyking/store/__10312__Turnigy_5A_8_26v_SBEC_for_Lipo_.html)
  Stiff plastic headband: preferably black.  I found one at a garage sale, but here's a cheap source I found for them online ($7.49 for 12) (http://factorydirectcraft.com/catalog/products/2346_1302_2533_2297-21165-1_black_plastic_headbands_12pcs.html)
  Black fur, white fur and grizzly black fur cloth:  I found these three at Joanns for about $5-10 a yard each
  Glue for glue gun
  Sheet of acrylic (1/8" should do): Picked one up for around $5 at the hardware store
  Metal brackets:  I used mailbox brackets that I picked up at the hardware store for $7 or so
  Gorilla glue

Optional Materials:
  Sewing Machine
  Black insulating tape
  Sand Paper

PhantomX9993 years ago
ok, this is my first electrical build ever and i need to ask. how do you charge the power pack?
abetusk (author)  PhantomX9993 years ago
You'll need to get a LiPo battery charger. The above build uses a 2s 7.4V batte
ry pack, so you'll need a charger that can handle a 2s battery pack. Hobby King
has one here:


but you can always shop around yourself by putting in 'LiPo battery charger' in
either Amazon or Google.
ya, might have wanted to added that in ''JIC''. the only other thing i might change is put all the stuff together that you got from hobby king. so when people order the parts as they go, not to put out multiple orders and having to pay for more than one shipping price.
ReCreate3 years ago
Even though I'm a furry, I have a little bit of difficulty getting what this is for... What is this for? O_o

Pretty brilliant regardless. c:
d0vr3 years ago
You list where i can find everything but an assistant? Where can I find one like yours and how much do they cost? (Can they be persuaded with animatronic cat ears?)
wow these will go great with my brothers cat bell i have to make these for his birthday he will love them and maybe he wont beat me up for an hour yayayayayayayay!!!!
p3av8or3 years ago
This is my first time using perfboard, and I'm having trouble figuring out what bridges you've made on the other side of the board. Sorry for the noob questions, but I don't have an electronics background. Thanks!
abetusk (author)  p3av8or3 years ago
I used the proto board I got from RadioShack (online here: http://www.radioshack.com/product/index.jsp?productId=2102846# ) and not perfboard. The main difference is that the copper traces on the proto board model a breadboard whereas the perfboard has isolated copper pads per hole. I've found perfboard to be messy and clumsy so that's why I used the proto board.

I would suggest getting a simple setup running on some breadboard, i.e. connecting the power to the regulator, the regulator to the circuit, wiring at least one servo out of the micro, connecting the button and testing before proceeding further. Once that's done, you'll have a good understanding of how to connect components together. You can use either protoboard or perfboard for connections, I just prefer protoboard as I find it easier to work with.

Send me a private message if you get stuck and I'll do what I can to help.
rhoult3 years ago
I'm a little confused here. Is there a simpler diagram for wiring this? i'm building this for a friend and am stuck on this step. Is there any help you could offer?
abetusk (author)  rhoult3 years ago
The above is a simple circuit showing the connection between the microcontroller, the servos and button. It doesn't include the regulator, battery or connection thereof. There should be four lines coming out of the ATTiny13, each going to the signal line of the corresponding servo. One line out of the ATTiny13 is attached to a button with a pullup resistor.

Each of the servos needs to be connected to the power line and grounded, along with the button, pullup resistor and microcontroller. The power should be from the regulator that provides a steady 5V from a lithium ion battery. The analogy is a wall wart: You plug in the wall wart into the wall socket then plug in your device from the wall wart to provide the power you need for your device. The 2 cell lithium ion battery is like wall socket power and the regulator is like the wall wart.

The 2 cell lithium ion battery is needed to provide the amperage necessary for the servos and the regulator is needed to provide a steady 5v and service the amperage draw needed by the microcontroller and servos (mostly the servos). Using a 9v or AAs might work (through the regulator, of course) but I've run into problems, I think because the amperage requirements of the servos is too heavy.

To figure out what color wire from the servo corresponds to power, signal and ground, I found the following web site useful: http://www.societyofrobots.com/actuators_servos.shtml .

I take it you're a beginner to electronics and so this stuff might be a little confusing. I hope the above addressed the confusion you had, but if it didn't, feel free to send me a private message to discuss this further.

Good luck and make sure to show pictures after you're done!
Wow ' but I had this technology for years and the parts I use don't exist . There all hand built drivers and are in all of my suits plus the tail even moves and lights up at tip also I'm glad there's others out there who are in to animatronics and just not me , Keep up the good work . Mountain Blue Fox Joe also crazyjoe1952 .
rhoult3 years ago
This might sound a little noobish, but what's the black box that you hooked the microcontroller up to to calibrate it?
abetusk (author)  rhoult3 years ago
I'm sorry, I don't know what you mean. The calibration step that appears in this instructable whereby the servos are aligned on the headband? Or do you mean some other type of calibration?
rhoult abetusk3 years ago
sorry, i found out what it was i was inquiring about, but how did you wired the micrcontroller? I'm a little inexperienced in the whole microcontroller thing...
Uptonb3 years ago
Congrats on being a finalist, and good luck!
jeanlafete3 years ago
A+ on Innovation! Your assistant is a doll and loves the expressions she does with the ears. Love to see more and how well the ears hold up. I would love to built, unfortunate I don't have the free time:-( Keep up the great work!
Oscar19863 years ago
This looks awesome. I went to buy the USBtinyISP AVR Programmer Kit, but it says it may or may not work with Windows 7. I have Windows 7 Home premium do you know if it'll work? or should I look for another one? and if so which one do you recommend?
abetusk (author)  Oscar19863 years ago
I believe that Adafruit is just hedging their bets and that it's not so much that it might or might not work on Windows 7, but that they haven't tested it on Windows 7 and can't cofirm it's functioning as expected. I just did a brief search on the forums to see if anybody had any problems with Windows 7 functioning with their USBtinyISP and it looks to be alright. You should do your own homework to confirm but I would bet that it would function fine on your system.

If you do end up going with Adafruit's USBtinyISP, make sure to follow the build instructions here ( http://www.ladyada.net/make/usbtinyisp/ ) with special attention to step 11 here ( http://www.ladyada.net/make/usbtinyisp/solder.html ) where you need to replace the resistors R4 and R7 by a jumper (see also http://forums.adafruit.com/viewtopic.php?f=20&t=15045 ). When I first bought the USBtinyISP, I found this instructable to be helpful as well ( http://www.instructables.com/id/Ghetto-Development-Environment/ ).

There are alternatives but I haven't used them so I can't attest to their reliability. Here are some li
nks, in no particular order:


You will need to make a target board for the target chips. You can see my very rough one in the 'Programming the ATTiny13' step of this instructable. You might be able to find premade target boards, if you wanted, by searching around. Just make sure that they're ATTiny13 compatible.

Here are some links that I found helpful when first starting out:


And just for completeness, a link on avrdude and programming:

and a tutorial on avr-gcc:

I've had good luck with the USBtinyISP. Adafruit is really good about responding to problems on their f
orums and I've been happy with mine. It may seem a little daunting at first but all you're really doing
is solerding a kit (at worst) and connecting point 'A' to point 'B'.

There is also the route of using an Arduino with an ISP shield to program your AVR's. EvilMadScience has one here ( http://evilmadscience.com/productsmenu/tinykitlist/253 ). There's also some instructables on the subject here ( http://www.instructables.com/id/Turn-Your-Arduino-Into-an-ISP/ ) and a tutorial here ( http://arduino.cc/en/Tutorial/ArduinoISP ). If you're feeling more adventurous, here's a HackADay article on it as well ( http://hackaday.com/2009/07/15/avr-isp-programming-via-arduino/ ). I haven't done this myself but maybe this would be easier for someone more familiar with Arduino's.

Good luck!
ignatzart3 years ago
My granddaughter and I are building these for her next Anime-con. I truly appreciate your clear instructions. We wondered if we could use submicro servos to cut down the bulk? We are new to this stuff so I don't know how to match the bits. What are the specs we would look for to substitute servos?
One thing though, the source you give for the ATTiny13 has a minimum order of 940 pieces YIKES! So we got one from Digikey.
abetusk (author)  ignatzart3 years ago
Thanks for pointing that out! I just picked on from the list that was a DIP and was cheap. I've changed the link so that it points to an ATTiny13 that has a minimum order of one from Mouser.

You have to be careful with the sub micros, they're really awesomely tiny but I think their torque is significantly reduced. Either the HXT900 or the TG9e have 1.5-1.6 Kg-cm torque whereas the SO361 sub micro that hobbyking sells ( http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=3715 ) has only .3 Kg-cm torque (or so). That's 5 times as less!

I've used the SO361 sub micro in a bunny mask costume with movable ears out of paper and fur (and glue), It mostly worked but I found that sometimes the motors weren't powerful enough to overcome the momentum of a moving ear, causing it to overcompensate and then start to go back and forth effectively making the ear 'wobble' (at least that was my theory on why it was wobbling).

If you are feeling adventurous and want to try the sub-micros, I would suggest at the very least using some sort of plastic arm instead of the metal bracket and either taking out middle portions of unused acrylic or just making the top front facing ear out of wire. I think the code should work without any change.

If you guys run into any problems and need help feel free to give me a message and I'll do what I can to help! If you could post some pictures after your build is complete, I would also appreciate it.

Good luck!
duodreamer3 years ago
This is the cutest thing I've seen all week, I've shared it with others! Great use of the micro servos. I have one contribution: replace the single pushbutton with a small joystick, like the type used in Playstation controllers. You could use the dual axis potentiometers on the joystick along with its internal pushbutton for pre-programmed positions or "live" control. SparkFun even sells these little units: http://www.sparkfun.com/products/9032

abetusk (author)  duodreamer3 years ago
This would require going up to a micro that had more input lines as that joystick needs 2 A/D lines and an input pin in order to have the full range of function. It's probably desirable to go to a beefier micro anyway as the internal RC clock on the ATTiny13 is a little imprecise causing the servos to jitter a bit.

Maybe I'll do this for "version 2.0".
arempert3 years ago
Do you think these servo arms would be strong enough to move around ears longer (or, essentially, heavier) than these cat ears?
abetusk (author)  arempert3 years ago
I used servos that are HXT900 compatible. Using those as a reference servo and looking at the servodatabase page ( http://www.servodatabase.com/servo/hextronik/hxt900 ) you can see that the HXT900 provides 1.60 kg-cm torque, so you can use that to calculate how much weight it can move based on the arm length.

Depending on what servos you actually get, their torque rating may be different than the value given for the HXT900, so you might need to experiment.
badmoonryzn3 years ago
I have been looking for years for a quiet set of mini servos and the only things I have found were a kind of mini magnetic linear actuator servo motor that cost a bloody fortune. Like 150 each. I found them on some electric motor/linear actuator stores on several sites on the Internet. I have a couple of the things but they are to big for these applications, but they are dead quiet. You might be able to find some in old printers and other devices that use them, some are very small but the control cards and code are a pain. Maybe slow down the motors and pack the gears with some kind of goo, but then they would not last long. Thanks for the idea and list of goods. This is a very cool device!! Nice job! I can't wait for my cats to see the things. They already think I'm nuts, but I have something they don't........... Kitty treats!...............Catnip..............FOOD!
X413 years ago
for the love of god, please make a animatronic cat tail!!!!
somebody already did several years ago: http://www.wolftronix.com/howto.htm
bob2023 years ago
Very Cool !!
YendorZ3 years ago
An interface easier than an EEG may be an accelerometer. Head tilts and gestures could control the ears pretty well, methinks...
dawg0653 years ago
john candy had something similar in the movie"space balls".yes i know they were dog ears.but still.i still think what you've done is really quite good.
rifakungen3 years ago
HAHA! Now THAT is one epic little project! :D Love it! good job!
mpinner3 years ago
really nice job! im considering what muscle wire would add to this.... likely less battery life, less control, but far more quiet.

any experience with this?

what kind of battery life have you been getting?

built any moving tails yet?


alzie mpinner3 years ago
I have tried to use muscle wire on a biz project, and
its difficult to do anything serious with.
Efficiency is only like 0.5%, and
you have to use up a bit of it fighting a return spring.
You must use a return spring to get push pull action, otherwise
it only pulls.
Thats why you dont see a lot of serious apps out there for it.

We gave up and went to a small hobby motor / gearbox.
abetusk went the right way.
abetusk (author)  mpinner3 years ago
I have no experience with muscle wire. I have had a lot of suggestions to use it but I'm just not sure it's the panacea that people think it is. It's definitely worth checking out so maybe I'll get to it someday.

The servos that I use are reported to draw 750mA maximum (check out some analysis done here: http://homepages.paradise.net.nz/bhabbott/Servo.html ). Assuming all four servos are drawing at maximum continuously, that's 3A (thus why I chose the 3A DC-DC regulator). The battery I use is 900mAh so that gives an approximate lifetime, if all four servos are in continuous use, of 18 minutes. So, at worst, lifetime should be about 20 minutes, at best maybe an hour or two? I have not done real testing in this regard so I'm not sure what kind of battery life you can expect.

As to the moving tails, all the videos online that I've seen don't give the amount of expressiveness that I would want and I don't see how to make them any better.
mirrorspock3 years ago
Very Cool, I'm working on a similar project, only I plan on using an ECG sensor to detect the mood of the wearer.
I have the hardware ready, just needed some inspiration on how to actually build the ears!
zack2473 years ago
oh WOW!
it would be really awesome to do something like this on a fursuit!
smmiller5063 years ago
Over on github, I saw that you had a schematic posted up (Kears.png) and noticed a small error - on "U5" in the top left corner of the schematic, the power lines are swapped. You have positive going to ground and negative receiving +5 VDC.
abetusk (author)  smmiller5063 years ago
Thanks, I've fixed this. I rotated the servo schematic around and forgot to adjust my thinking accordingly. I'm actually using upverter.com to do the schematic ( http://upverter.com/abetusk/2ff4634ff64db304/Kears/ ) and it takes a little while before the change propagate through and are available for .png download. When it's available I'll update the instructable and the github repository.
witchdoc3 years ago
This is hilarious! I love it! And a really good build too. I'm quite impressed.
Yep. Winnar! Good stuff.