Wednesday, 4 December 2013

Draft Tutorial

Drawdio an open sourced project established by Jay Silver. Various sources influenced his original circuit design and to continue the evolution of the project, it has been uploaded for experimentation and moderation. The design essentially turns the act of drawing into sound, through the conductivity of graphite and interconnecting touch, through the conductive human body. The sound produced fluctuates depending on the resistance between pencil point and finger point.

Our objective is to develop the existing design by directing the project into a stage of refinement. Starting with reducing the scale of the electrical components, as well as in housing the design but still allowing creative freedom for further iterations. Our contribution to the Drawdio design introduces digital manufacturing, by implicating the use of milling PCB boards and 3D printing.

The aesthetic of our model was influence by our research into ergonomics, we wanted to portray notions of a futuristic, resolved product. The organic curve allows the pen to sit comfortably in the hand, developing on ergonomic properties. The grip and symmetrical body is also suited for a wide audience.

Equipment you will need :
- 3D Printing Facilities
- PCB Miller or Etching Equipment
- Thin Tip Soldering Iron

Components you will need :
- 9-10mm O-Ring
- Modeling Glue or Araldite/Epoxy 

Electronic Components you will need:

Name / Manufacturer & Part Number / Element 14 Order Code

- RESISTOR, 10M, 0805 1% 0.25W / MULTICOMP - MCHP05W4F1005T5E / 1576520
- RESISTOR, CERAMIC, 10K, 0.125W, 5% / MULTICOMP - MCMR08X103 JTL / 2073612
- RESISTOR, ANTI SULFUR, 10R, 0805, 5% / MULTICOMP - MCMR08X100 JTL / 2073604
- RESISTOR, 270K, 0805 1% 0.25W / MULTICOMP - MCHP05W4F2703T5E / 1576499
- TRANS PNP 40V 0.2A SOT23  3906/ NXP - MMBT3906,215 / 1757936
- CAPACITOR, 100UF, 16V / NICHICON - UWX1C101MCL1GB / 8823065
- CAPACITOR CERAMIC, 0.1UF, 25V, X7R, 20%, 0805 / MULTICOMP - MC0805B104M250CT / 1708716
- CAPACITOR, MLCC, 0805, NP0, 100V, 1NF / MULTICOMP - MC0805N102J101CT / 1759288

The components for the project were purchased at element14 a worldwide supplier of electronics. The components used are surface mount packages, so a decent soldering iron with a thin tip and magnifying equipment is recommended. The parts list here is not set in stone basic components such as your resistors and capacitors can be of different manufacturers to get the smallest minimum order and reduce the total cost which should be around $8 -15. 

Files you will need:

Eagle & PCB Files: Files

3D Printing Files: Model Files

How the circuit works: 

Our test run with a breadboard, we recommend you try this.

Drawdio Schematic
Images sourced from:

The circuit in essence is very simple the 555 Timer Chip is wired to operate in an 'astable' mode that outputs a contant pulse from pin 3, this pulse changes in frequency and subsequent audible tone depending on the resistance between pins 2 and 7. The overall tone can be changed by adjusting the 1NF Ceramic Capacitor. The pulse outputted is then amplified through the PNP Transistor that allows the full voltage to the 100UF Capacitor and Speaker.

Milling Circuit Board: 

From Eagle, exported into a monochrome .png

Milling path - use 1/64 bit

Cutting path - use 1/32 bit

  • Download the PCB Eagle file, the monochrome .Png images are read as the trace paths for the milling. In this case we used the CNC Roland Modela to make our circuit boards. 
  • Make sure your copper sheet is attached firmly to the bed before proceeding to load the .Png image for the circuit path, then select create path followed by create .rml and send it. 
  • Set the x,y coordinates, make sure you remember these as it is important to reset them back into the correct place for the cutting path. 
  • Use the 1/64 bit for the milling traces, ensure the tool bit it sitting flush to the material. 
  • Once this is complete load the cutting path .Png image and change to the 1/32 bit before resetting to starting coordinate point. 
  • Clear away any copper shavings and rough edges.   
  • Final Size : 35mm x 12mm
  • Drill using 1mm bit, within the circular patterns located on the circuit board. To later solder the wires that go to external components.

Soldering Circuit Board:

Labeled Diagram to show where components go:

Key of components: 

270K Resistor- limiter of the electrical current that flows through the circuit. The electrons that pass through the resistor are changed to energy.  

10M Resistor

0.1UF Capacitor Ceramic

1NF Capacitor Ceramic

555 timer chip- low power- generating pulses used for basic timing functions, it can also produce musical notes at a particular frequency. A standard design has 8 pins all with individual functions.

Transistor- In this case it is used as a amplifier, designed so the properties of the current change in voltage from a small input to a larger output.

10K Resistor Ceramic

100UF Capacitor

10R Resistor

  • The electrical components are exceptionally small so we advise you have a useful pair of tweezers and a magnifying glass. Ensure the board in secured to a flat surface or clapped in place. 

  • We advise to not to keep the soldering iron for a extended period of time on the transistor and the timer chip as these components are heat sensitive.

  • Make sure the components are individually soldered to their correct paths especially the timer chip. 

3D model and printing:

            Download STL file of the housing constructed with internal components to secure the electrical elements. The file has been process in Netfab to ensure the model is compatible for 3D printing and there are no errors. In this case our 3D printer is support by Up! Software to set-up a print.

            During setup for printing we suggest a Z resolution of 0.15mm to generate a smooth surface and a base height of 2mm, our angle degree for the print was set to 30 Deg and the surface was set to 3 Layers. To ensure the form of the housing is strengthened we suggest a fill in the mid-high range.

            Select a material- PLA (plant based) or ABS (oil based), we used ABS. Make sure you give the plate time to heat up before printing. Print will take approximately 2 hours. Once the print has finished let it cool and carefully remove the support material.

Printed Result:

Wiring battery and speaker to circuit board : 

  • With the complete circuit board and all elements have been constructed, route the speaker lead through the holes located on the board and solder them to the circuit board. Do the same with the battery, we are using a 3V lithium button battery. Secure both components in their allocated location in the housing.

  • Lead the resistor wires through the paths shelled in the housing and make sure it is connected to the graphite lead, the 2nd wire wraps externally in the grooves of the outer shell and ensure they are touched when gripped.  

  • Once all the components are sealed internally in the housing, add a small amount of glue to the joining notches and compress the two halves together and hold.  


  • The casing is designed to hold a 6mm graphite lead. It is important for the lead to be touching the copper wire inside the casing, for the pen to make a sound. The lead is pushed into the casing and held in tight with an O-ring.


Drawdio is an innovative project that encourages the exploration of technology and design. We have taken what was a chucky, home DIY design and refined it into, effectively an elegant product. We aimed to further strengthen the project and continue the evolution of the open design. In doing so our share files and the tutorial proposed, will inspire further iteration of the project.

This project responds and adapts an original open source design--->


Heres a link to our thought process and developments ---->

Open Design Project Wgtn

The team: Ben, Chad, Emma & Maddie