By: Jared Ireland, Sylvia Slakva, Tim Chou
- Sketching your circuit on paper is one of the quickest and best ways to plan out your circuits. It’s excellent for getting a rough draft going or refined some of the more complicated parts of your circuits. Your sketches can be applied or transferred to fabric patterns via hand drawing or a drawing machine.
- The CPX is great for paper prototyping because the PIN holes can be easily traced out onto paper.
- Knowing your symbol conventions are essential in creating an accurate and understandable circuit diagram. For this workshop you should familiarize yourself with the LED, resistor and photocell symbols. For more useful symbols, visit this website: Circuit Diagram Symbols
Circuit Prototyping – Why use Aluminum Tape?
- Breadboards are good for prototyping hardware but not so well for soft-circuits.
- Alligator clips are useful for prototyping with the PCX but they can get messy easily and aren’t great for planning a two-dimensional circuit.
- Aluminum tape is a great affordable prototyping tool that can be purchased in any hardware store (ex. Home Depot, Canadian Tire).
- If you just finished sketching out your circuit diagram you can easily test it out by laying aluminum tape over your sketch to replicate the circuit.
- Copper tape is a better alternative because it’s more conductive and easily soldered to, but it is harder to find and costs much more.
Turning your Sketch Diagram into a Working Circuit
- Using aluminum tape is great for quickly converting your sketch diagram into a testable circuit.
- You can start by cutting long strips of aluminum tape beforehand to save time. Using a rotary blade cutter to cut the aluminum tape is much cleaner and more effective than using scissors.
Techniques to using Aluminum Tape
Fold-Over-Overlap + Tape-Over-Overlap:
- Fold the end of a strip of aluminum tape and tuck it under the sticky side of another strip so that it holds the folded strip in place, then lay down the folded tape so that the aluminum faces are touching.
- Align 2 strips with one’s end overlapping the other’s, then fold the end overlapping strip so that aluminum faces are touching before taping over the joint to secure it in place.
- Line up or overlap 2 strips of aluminum tape and sew through both of them a few times with conductive thread.
- Prepare 2 short strips of aluminum tape so that one of them is at least ¼” shorter than the other, then align the 2 strips at the center and stick the adhesive sides together so that you have a double sided strip with a sticky side on each end. Use this to bridge the gap between 2 strips continuously.
Troubleshooting and Connecting Components
- Using a multimeter can be useful for testing if your circuit has continuity because it’s really easy to mess up your circuit if you don’t apply aluminum tape properly.
- Aluminum strips have an adhesive side which keeps your circuit in place but can also insulate so it’s not a good idea to overlap a strip over another to extend the wire. You also can’t tape over a LED or resistor leg over another strip of tape because it will break the circuit.
- Piercing through the aluminum tape with the LED or resistor legs can help you get a solid connection.
- Make sure to position your CPX properly on your circuit to get a proper connection and avoid a short circuit. Holding down the PINs the circuit uses can establish a stronger connection as well.
We prepared three circuit planning challenges for you to try out with the aluminum tape and handouts that were given out in class.
Simple Circuit Challenge
- 3 LEDs
- 3 200 ohm Resistors
- Aluminum Tape
- Pencil + Paper
- On the simple circuit diagram, Sketch three series circuits with an LED and resistor in each. Use pins A3, A5, and A6 as outputs and use only one GND pin.
- When you finish sketching your circuit, lay down strips of aluminum tape over where the wires should be.
- Upload the simple circuit code and lay your CPX on top of the one in the diagram to test out your circuit.
NOTE: Your circuit can be a bit funky especially when first starting with aluminum tape so you may need to press down on some points of the circuit to keep the connection going through the circuit.
Simple Circuit Code
Advanced Circuit Challenge
- 3 LEDs
- 4 Resistors (220 ohm)
- Aluminum Tape
- Using only the right half of the CPX, create a circuit diagram that uses one photocell and resistor connected to pin A6, as well three LEDs and resistors that connect to pins A4, A5 and A7.
RESTRICTION: The LEDs and photocell must be spread out around the template without crossing the circle in the middle, or go outside of the outer hexagon.
NOTE: Photocells (or photoresistors) are light-sensitive variable resistors that change the resistance based on light levels. The higher the light it detects, the lower the resistance.
Advanced Circuit Code
Demo Circuit Challenge
- 1 LED
- Resistor (220 ohm)
- Aluminum Tape
- Pencil + Paper
- Draw a series circuit of a resistor and LED that uses A2 and GND. Instead of connecting the LED straight to GND, draw a line from the LED to the bottom right corner of the paper before going back to GND.
- Draw a line from A3 to the top right corner of the paper.
- Place the LED and resistor on top of the spots you drew your diagram. Lay strips of aluminum tape where you drew your lines and over the legs of your resistor and LED.
- Place your CPX on top of your diagram and upload the demo code. When the code is uploaded, fold the top right corner of your paper over your bottom right corner to light up your LED.
Demo Circuit Code
RESOURCES & REFERENCEs
Circuit diagram symbols. Lucidchart. (n.d.). Retrieved March 18, 2022, from https://www.lucidchart.com/pages/circuit-diagram-symbols#:~:text=families%2C%20outlined%20below.-,Electrical%20circuit%20diagram%20symbols,zigzag%20lines)%20reduce%20current%20flow.
Ada, L. (n.d.). Photocells. Adafruit Learning System. Retrieved March 18, 2022, from https://learn.adafruit.com/photocells/arduino-code
A. (2017b, February 28). Chapter 6: Adding the photocell. Arduino to Go. https://arduinotogo.com/2017/02/28/chapter-6-adding-the-photocell/
HOW TO GET WHAT YOU WANT. (2022). Kobakant. https://www.kobakant.at/DIY/?p=6607
Circuit Stickers – Jie Qi. (n.d.). Technolojie. https://technolojie.com/circuit-stickers/
E-Textile Swatch Exchange. (n.d.). E-Textile Summer Camp. http://etextile-summercamp.org/swatch-exchange/felted-game-controller/
Sketching in Circuits – Jie Qi. (n.d.). Technolojie. https://technolojie.com/sketching-in-circuits/