Drawdio

The Drawdio was invented and developed by Jay Silver and Adafruit and is an electronic pencil that lets you make music while you draw. The Drawdio circuit is made from fifteen parts including a circuit board, capacitors, ceramic capacitors, resistors, transistors, a timer chip, a speaker, copper foil tape, a thumbtack, wire, and of course, a pencil. The reason a pencil is used instead of a pen is because the graphite from the pencil is a conductor, there for electricity can pass through it enabling the Drawdio to function. How does it work? While writing with the Drawdio, the contact from the graphite and the paper completes a circuit that allows sound to be created and emitted through the speakers. Contact with your skin also accomplishes this. The reason being is that people are conductors of electricity and if you touch the end of the pencil’s graphite or both sides of the pencil where the copper tape is placed, you are completing the circuit which allows the electricity to flow through you body and make the pencil work.

Here’s a link of site that demonstrates how the Drawdio works through a fun and interactive game: Drawdio!!!

Step-by-Step Instructions

First need to start off with all the required parts.(off switch is optional)
File: parts-1.jpg

Set up your circuit board or PCB in a vise and heat up the soldering iron to 700 degrees F.

Now your ready to start soldering.

Picture Instructions
image: 10k.jpg The first thing that will be placed is the 10K resistor (this one is brown, black, orange and gold), it acts as a brightness indicator for the LED. What you do is bend the ends of the resistor and slip it inside of the PCB. Place the resistor in the spot marked RA. The resistor does not have polarity so that means you can place it any way you want to.
Next, turn the PCB over, showing the iron side and begin to solder the tips of each side for about 2 to 3 seconds. Make sure the that you have not exceeded the boundary of the section you have soldered. After you have finished soldering, you can go ahead and clip off the end with angel cutters.
Next put in the 300k resistor (the one that is striped Orange, Black, Yellow, and Gold). Solder in this resistor the same way you did with the first resistor and after soldering it, clip off the ends with the angel cutter. Afterwords, the back of the PCB should look the the picture in the left column.
Next are the two ceramic capacitors C1 (blue) and C3 (brown). Ceramic capacitors also have a nice property that they are symmetric/non-polarized. That means they can be placed in either way. The capacitors are different values so make sure to not mix them up.C3 is a 0.1uF capacitor and has a “104” marking on it. C1 is the 680pF capacitorand has a “682” marking on it.

Place the capacitors so that the 2 legs (leads) slide through the two metal holes in the PCB (pads). The capacitor will sit flat against the PCB.

Use the same instructions as before and fold the ends of the capacitors so that they fit into the spots in the PCB pad. After you have done that, as before, solder in the ends and afterward clip them off with the angel cutter.

image: veroboard.jpg Next is the heart of the kit, a low voltage 555 timer chip. This one is called the TLC551. The important thing to note about the chip is that it is not symmetric. If it is put in wrong it will not work! Its also nearly impossible to fix if the chip goes in wrong so make triple-sure before you solder it in!The silkscreen on the PCB has a little notch in the top. That notch indicates where the top of the chip is. If you look on the chip, there is a circle/dot imprinted in it on one end. There’s also a TI logo at that side. Make sure the chip is inserted so that the top of the chip lines up with the silkscreen notch.

Solder in all 8 pins. You might want to use a piece of tape to hold the chip in place, or use a spare finger if you are dexterous.

The leads are very short to they wont need clipping.

image: wire.jpgimage: spk.jpg The electronic components are soldered in, next it is time to attach the speaker. Use the diagonal cutters to clip off 2 2-3″ pieces of wires.Next, nick the insulation 1/4″ from the ends of the wire, and pull it off. If you have wire strippers, use them as they are a little easier!

Next, it is a good idea to tin the ends of the wires. Its a little tricky because it requires holding three things. However, if you have a ‘third hand tool’ or a vise, you can use that to hold the wire while you heat up the stripped end and coat it with a little bit of solder. This will make it easier to connect to the speaker.

On the opposite side of the speaker there are two solder tabs. Heat them up and add a little more solder. Don’t spend too much time on them (more than 3-4 seconds) since the speaker is made of plastic and if it heats up too much it will melt!

Next, warm up the tabs and slide the tinned ends of wire into the melted solder pool. Then remove the iron and wait a few seconds, the solder pool will cool with the wire in place. Do the same for the other pad

Twist the wires, this will reduce the strain on the solder joints when bending. Put the end of each wire into the PCB hole marked SPK. The speaker is ‘symmetric’ so it doesn’t matter which wire goes in which hole.

Solder the wires into place.

image: draw.jpg Next you can mount the PCB to your pencil. Place the PCB on the flat side of a pencil, and thread the zip tie through as shown and tighten it. You’ll want it about an inch or less from the top of the pencil. The higher it is the more pencil you’ll have to sharpen but it may be a little more unbalanced.Next cut a 1.5″ piece of copper tape using the diagonal cutters. Don’t use scissors as the metal tape can damage them. peel off the paper backing. The copper tape is conductive, sticky and flexible which makes it perfect for wrapping the pencil

Wrap the tape along the top of the pencil so that the beginning is at the silver metal tab on the PCB, as shown

Then take the thumbtack and gently push it into the end of the pencil. You might have to twist it back & forth a little to get it all the way in. The thumbtack will grip the copper tape and also make contact with the graphite in the middle of the pencil to make the first half of the drawing sensor

Finally, insert a battery and turn on the kit. Then grip the pencil with one hand and touch the point of the pencil to your other hand. You will be able to hear the Drawdio make noise!

Next up, see the user manual for ideas on how to make the most of your drawdio