Drawdio: A pencil that lets you draw with music! - The Drawdio kit was designed in collaboration with Jay Silver based on his original design.

When I first saw the Drawdio at Maker Faire I knew it would be a great project for beginners: A lot of fun with instant gratification! Essentially, its a very simple musical synthesizer that uses the conductive properties of pencil graphite to create different sounds. The result is a fun toy that lets you draw musical instruments on any piece of paper.

  • Runs on a single AAA battery for many hours (even 'nearly dead' batteries will work)
  • Use any pencil - mechanical or plain. The kit comes with a 2B pencil, the softer the lead the better
  • Ridiculously fun for all ages


The best way to see how Drawdio works is to watch a video...

Here are some videos from JJ Silver himself! These videos are of an earlier revision so it looks a little different

Here is one of me playing with my kit right after building it


The Drawdio kit was designed in collaboration with Jay Silver & based on his original design!

Step 1: Design

How does it work?

The Drawdio kit is pretty simple compared to most electronic projects.

We will go through it one section at a time, please refer to the schematic

Power supply

The first part to understand is the power supply, which keeps everything running. The power source is a single AAA battery which is held in a plastic container that is soldered to the PCB. There is also a switch S1 which can connect or disconnect the battery from the rest of the circuit. Finally there is a large electrolytic capacitor C4, which is used as a 'bypass capacitor'. This means that it goes across the AAA battery and smooths out any ripples that are caused from power surges (like when the drawdio makes noise!)

The Oscillator

The heart of the kit is a TLC551 chip, which is a low voltage version of the famous LM555 timer chip. This integrated circuit is specifically designed for creating timers and oscillators. The original LM555 needs at least 5V to run (which is more than 3 1.5 batteries!) so we are using the 551 which can run as low as 1V. Its a little more expensive but makes the whole thing fit on a pencil.

One of the more popular ways that '555s are used is as a 'astable multivibrator' which is another way of saying an oscillator. The frequency of the oscillation is set by 2 resistors and a capacitor. The chip slowly feeds current into the capacitor until it is full and then, likewise, slowly drains it out. The resistors set how fast to fill and drain the capacitor and the size of the capacitor indicates how long it takes before it fills.

This system is pretty much identical to Japanese water fountains, as this video shows:

Except its all with electrons instead of water molecules and capacitor C1 is the 'bucket'. The water fountain oscillates maybe once a minute (1/60 Hz). But electrons are so much faster, a '555 can oscillate at thousands of Hertz, which means it can make audible sound. (Human hearing tends to range from 20Hz to 20000 Hz)

f = 1.44 /(C3 * (RA + 2 * RB))

C3 = 680 pF = 0.00000000068 F
RA = 10000 ohms
RB = 300000 ohm to 1000000 ohm (1 Mohm)

In this case, we use two resistors RA and RB but also have an 'open connection': two tabs at the end of the PCB. If the two tabs are shorted with a piece of wire, then the frequency of the oscillation is 3500 Hz, if instead there is a resistor of 1 Megaohms between the two tabs, the frequency of oscillation is about 1000 Hz. You can use a calculator to do the math yourself using the formula above

Instead of a 'everyday' resistor between the tabs, however, we use something else - the conductivity of the human body and graphite! The human body has a resistance similar to a 200,000 ohm resistor. Graphite has resistance of about 1 ohm per inch when its in the form of a pencil lead. When its spread out on a piece of paper, the resistance goes up a lot, up to a megaohm for a few inches of 'drawn resistor'


The 551 can create audio-frequency oscillations but it is not powerful enough to play them on a speaker, just like an MP3 player needs an amp to play music on large speakers. That's because the 551 was designed mostly for digital logic, not for low impedance (8 ohm) audio outputs. So we will use a Class B 'pushpull' amplifier, which uses two separate transistors to amplify the sound.

This is pretty much the same thing in your stereo, except your stereo has enormous transistors with gigantic heatsinks so that it can drive large speakers.
<p>I'm looking for someone to demo Drawdio on BBC Radio - just down a phone line or on Skype would be fine. Its for a music feature this weekend on Saturday morning. Please could you call me on 0782 6762481. Many thanks, Michelle Dawes, Producer </p>
<p>This is my first version of this proyect, from Argentina!</p>
The materials shouldn't cost more than $20 (US).. Looks like the priciest item is the copper foil tape, and you might be able to shop around a bit to find a decent deal.
<p>Either order it from AliExpress (under 2$/roll) or use aluminium tape or even alumium foil instead. A wire would also work.</p>
Wow. This looks like fun. Can the pitch be changed to have deeper sounds?
Hi, I made the Drawdio, and it makes an extremely high pitched noise, and It doesnt matter what resistance it makes the same sound, but it has to have a resistance to make the noise. What can be wrong? could some flux residue cause this problem ot some short? thanks
I measured the frequency on pin 3, it was 6.5 KHz, under 10Mohm resistor if that helps, by the way it worked perfectly on a breadboard.
I measured the frequency on pin 3, it was 5.3 KHz, while shorted. please help me make it work.
I fixed it, when i finished soldering i put the 555 timer into the socket, but when i needed a longer sense wire i soldered it without removing the ic, therefore these problems were solved by changing the 555 timer ic.
anyone know how i can print this using the toner transfer method?
I received a 6.3 volt capacitor (the blue one on your parts list) from adafruit industries in the mail but the one that you show is a 10 volt. Will mine still work for this project? Also, do I need one or two of them?, because you stated 1 for quantity here on your parts list but show two of them on the next step. And is an on/off switch absolutely neccessary?, because I didn't receive one of those in my kit either. Lastly, I received only one transistor, you show two. What should I do?
6.3 V cap will be ok since you're gonna work with a 1.5V battery ... <br>(the voltage on those electrolytic caps is the maximum you can use them with)
So simple... and so great! Congratulations! Question: how would the contacts be connected to a mechanical pencil? Do you have any photos of that? I was thinking and thinking and couldn't find a good way. By the way, what kind of mechanical pencil? 0.5mm, 0.7mm, or another one thicker? Suggestion: Please add extra warning to NOT solder the battery holder with the battery in place. The soldering heat might damage the battery and maybe the battery could explode.
Try soldering to the metal tip that comes out the end of the tip of the mechanical pencil.
Hey,<br/>I have some notes on this on the Drawdio website here<br/><a rel="nofollow" href="http://web.media.mit.edu/~silver/drawdio/make.htm">http://web.media.mit.edu/~silver/drawdio/make.htm</a><br/><br/>The basic trick is to attach one side of the circuit to a *metal tipped* mechanical pencil. I like 0.7mm but try a couple out and see what you think. You can test them before even mounting: just draw a line and touch (or clip) one side of the drawdio to the line... then hold the other side with your hand and touch the other end of the line with your hand.<br/>
Ah, I forgot to add: 1 Volt could be potentially dangerous if you had an open wound on both fingers while using this (allowing blood to contact the graphite and the copper foil) unlikely, but a warning, as the current could pass through your heart.
So ground is the positive of the battery?
No, ground is always the negative.
Right,...I must've misread the battery in the schematics
Wait, is this at the Faire every year? Sadly, I won't be there this weekend. I was there today, but no drawdio :(<br />
haha this reminds me of my theremin
the best thing is, i have all the parts in my &quot;parts that i probably shouldnt have bought&quot; draw! definatly going to make this.<br /> <br /> Is the main IC a bog-standard 555 timer?<br />
WOW!! I just looked at the videos for the first time. This is fantastic!! Can't wait to try it out at the maker faire! maybe even build it.&nbsp;:D<br />
Hi! What is the price of all the parts and do you where can i get them if i am not in the USA (cause i`m in Bulgaria)?
adafruit ships internationally :)<br />
The C3 value in the calculations doesn't match the schematic :/<br /> Noticed the same thing on ladyada's site.<br /> <br /> I'm using TS555C with a coin cell battery and I'm only getting low hz almost none changing static :(<br /> <br /> Not sure what that could be...<br />
question from utter newb. like i dont know jack.<br /> but if i bought the kit how would i add a line out type deal so i could put it through guitar pedals and computer effects and the like.<br /> thanks<br /> jook<br />
oooh a line in too.<br /> teehee<br />
i use 5 volt but why 555 do not work?<br />
It sounds like a dentist drill......
these're kinda annoying? doesn't anyone else think so, hah.
do u know if i could buy it pre made<br/><em></em><br/>
Do you know of a way to change the pitch of the sound?
my C2 has 681k on it... P.S., This is awesome
finaly tictactoe is funner then ever (im tired of always tieing)
Thanks a lot I have always wanted to make one of these but didnt want to buy the kits, is it possible you have a schematic to make one of these on a veroboard as i cannot purchase a PCB nor make one. Thanks again
Instructions on using stripboard (Veroboard) with link to the schematics if you can't get hold of the kit.<br/><a rel="nofollow" href="http://www.2ne1.com/drawdio/">http://www.2ne1.com/drawdio/</a><br/>
I bought all of the parts from the links you provided, but when they arrived I realized you linked to an 18pf capacitor instead of 680pf. Is this correct?
It should be a 680, but don't sweat it, just throw that sucker in there and see how it sounds.
I just bought the kit, came in the mail today. but i am missing a 300kohm resistor. it didnt come with the kit. would it still work if i attach three 100kohm resistors instead?
Yes it will still work that way. In fact it will work with any resistor from literally a wire all the way to a 1Mohm resistor, though i like it with 100k to 500k best. The beauty of this circuit it that it's old and tough. hook it up some different ways and see what happens.
It's just like the pen from Picture Pages with Bill Cosby!!
i was so just going to post a reference to picture pages! i just ordered the best of 'the electric company' on dvd. can't wait for it to get here. cheers!
Man that brings back some memories - The Mortimer Ichabod marker.
It's fantastic!!!
Dude you should make a kit and sell them to ppl. It would be coole.... 5 bucks for them pre assembled and like 3 for half assembled and like a buck for all of the materials and instructions..... I would so buy one....
Lady Ada does sell these kits... From Adafruit Industries
Where i'm from the battery holder itself costs 1$, you might want to re-evaluate the cost ;)
You are awesome!!! The idea, the transformation and the presentation...... This is the best innovation for low budget, I've seen for a long long time!! --> I LIKE.

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