How to Draw a Working Flip-Flop

Conductak, AgIC, and Chibitronics were all at an event recently, and an interesting gentleman named Quantum Wei asked what the coolest thing made with our products was. We offered up examples of papercraft and origami, but Quantum clarified, asking if someone had made "like, a flip-flop or something".

I'm an electrical engineer, so that made my day! A flip-flop is a circuit that can store 1 bit of information, and is the building block of computer memory. I quickly found a simple flip-flop circuit with my phone (an SR latch, cue arguments over what counts as a flip-flop) and offered to let Quantum be the first to use all three products to draw 1 bit of memory.

He gave a heroic effort, but his skills were a bit rusty, and we didn't have all the exact components (you can see his attempt, with the red and blue LED). So now I've taken up the challenge and drawn my own flip-flop using Conductak, the AgIC Conductive Ink Marker, and Circuit Stickers!

Step 1: Materials and Template

I used:

• 1 Ball of Conductak
• 1 AgIC Conductive Ink Marker
• 1 AgIC Circuit Eraser
• 2 Circuit Sticker LEDs (colors other than blue or white work best here)
• 1 Sheet of photo paper
• 2 Tactile push buttons
• 2 NPN transistors (3904, but pretty much any should do)
• 2 10K resistors
• 1 Coin cell battery
• 1 Paperclip

I drew traces for the circuit first with the AgIC marker, and the eraser is nice for making mistakes. I just freehanded it using the schematic and component dimensions as a guide.

Step 2: Circuit Stickers and Conductak

Stick the circuit stickers to your traces, following the flip-flop schematic. The stickers really grab onto photo paper, so make sure they're aligned right the first time! Each LED sticker has a 150 ohm resistor built in (100 for blue and white), so you don't even need to add one yourself.

Next bend the legs of the transistors out, making sure their orientation is correct (legs down, flat side facing you, should be EBC). Line the legs up with the traces, then stick them down with some Conductak. Once the transistors are in place, plug the resistors into the Conductak blobs following the flip-flop schematic. Make sure their legs don't touch each other (don't cross the streams!).

Step 3: Buttons

Get your tactile push buttons and line them up with the traces. I couldn't find two matching ones, so one's got legs and the other has SMD pads. Doesn't matter with Conductak. Stick your buttons down. Try doing that with tape!

Step 4: Battery and Play!

Stick a bit of Conductak to the ground trace, and stick your coin cell battery down. Complete the circuit with more Conductak and a paperclip to connect the positive side of the battery to the positive trace. When the flip-flop turns on, the universe will decide the initial state for you.

Push the button under the light. This grounds the transistor base under the light, and the light turns off. The voltage under the light goes up, which the opposite transistor base sees through its 10K resistor. The opposite transistor turns on, which turns the opposite light on. The voltage under the opposite light is now low, which the first transistor base sees through its own 10K resistor, which keeps its light off. Flip-switch-repeat!

Conductak is aiming to be commercially available by the end of this year to early next year. If you want to know exactly when that happens visit our website and sign up for our newsletter! Thanks for reading!