Munny DIY - Valentine's gift

Me and Ana always exchange "things we've done" for Valentine's, this year I got a knitted cap and a scarf. Since my ability to do anything "pretty" is quite limited, I thought about buying something and modifying it.

I saw a mini-Munny from Kidrobot in a local arts shop (Artifac), and I thought of the possibility of making it a bit more "interactive". The mini-Munny is a small DIY toy (you can paint it anyway you like) and made of transparent Vinyl and is available on various colors. I thought of placing a RGB LED that would sense the environment temperature and would change color accordingly. I though of using a Atmel AVR ATtiny15L driving directly a RGB LED from Sparkfun and using a LM35CZ to read the temperature. The ATtiny15L appeared the best option, I had some in my parts boxes, works from 2.7 Volts up, is programmable in circuit and has a ADC converter, useful when the only temperature sensors I have are analog output.
At this time I decided to use a color code for the temperature, blueish tones to cold temperatures (less than 19C), from 19C to 21C greenish, and from above 21C reddish. I placed 100Ohm resistors in each output to the LED so that programming in circuit was still possible, a better selection of resistors could save power but for now it was just enough. The supply of the temperature sensor is connected directly to an micro output, just turning it on when a measure is in progress, I also placed a RC filter on the output of the temperature. The LM35 was what determined the supply voltage and the number of batteries, its minimum operating voltage is about 4V, so I had to use 3 coin cells (4.5V).

The I built a small circuit board, with a SMD version of the Atmel, the LED, the temperature sensor and the ISP connector. I added a small blob of transparent FIMO to mix the output of the LED.

I was luck, the batteries "just fit" Munny's neck and the circuit also "just fits" the Munny's head.

Finally, the circuit is inserted inside the Munny's head and gives a colorful indication of the temperature every 3 minutes... or about...
Here is cold... blueish...

If you want to see more colors and other pictures, Ana has posted some more photos with other colors.
The original idea was an electronic Valentine's card... but I could not find any suitable carrier for it... you can't just give a breadboard to your Valentine's can you!! It was a ATtiny26L and a Nokia3310 display.


Ana said...


Nick said...

It looks very very nice.
Better than with the nokia screen :)



marchina said...

great idea i want to make something like this but instead of room temperature i want it to conect to my linux server and change color depending on the CPU temperature :D

but still great idea man

iphone-unlock said...

Munny images

Westley (Ludo) said...

This idea is really cool. I want to build one myself but don't have much electrical experience. I am so close to figuring this out, but I can't figure all of the parts you use. So far this is what I see: RGB LED from Sparkfun, Atmel AVR ATtiny15L, LM35CZ, 3 coin cells (4.5V), 10k Ohm resistors 5%tolernce (2), and 3 3.1 ohm resistors 1%tolerance. I can't figure out exactly what you use for each part. I was wondering if you could send a schematic and maybe a parts list if it isn't too much trouble. If you could help me get past this roadblock it would help me greatly.


Quppy5 said...

Hi there.
I love your project. I want one and I have no knowledge about electronics. I called a electronic shop here and sent them the parts list. 2 of the parts is out of stock. the thing is. someone told me that I have to program the ATtiny 15L. I have no clue how to do that. will you help me please ?
my e-mail address is raga@healthsystems.co.za

nall said...

Not to take away at all from this design (it inspired mine), but I have code and a schematic/board here:


I use a couple different parts in mine based on what I had available.

Thanks to João for the idea!

Bryan said...

I was wondering if i could use this iea for a school project. I was wondering if you'd mind and if possible could i get your code? My school project requires i attach a LCD display to it.. I'll send you my modified code once its finished if you like.

I use a PIC18F5242 with MPLAB IDE

Mazzy Blue Studios said...

Oh I love this you need to make these and sell them:) I want one!!! I'm an artist and not a computer guru but would love to have one for my studio all the same:)