Typewriter
Main idea
Our main idea was to upcycle two old typewriters and make them talk to each other by making them send messages to each other. For this, our platform of choice was Arduino. We used two Arduino Uno boards to control the typewriters. One of the typewriters would be used as an input (the white typewriter) and the other one would be used as an output
(the black typewriter). The input typewriter would be able to detect the keystrokes and send the message to the output typewriter when a new line is detected (when the lever gets pushed right). The output typewriter would then receive the message and print it out on a piece of paper.
Input Typewriter
We tried out various different ways to detect the keystrokes. We tried using a Photoelectric Sensor, but since we only had 3mm of space available between the keys, this didn't work out. We also tried using a Ultrasonic Sensor to detect the distance from the side, but this also didn't work out, because the sensor was not accurate enough. In the end, we decided to use one resistor for each key, all connected in series to a single analog pin. Then we grounded the typewriter's metal. This way we could detect the keystrokes by measuring the voltage drop across the resistor. This ended up working very well and we were able to detect the user's keystrokes very accurately. With this done we moved on to the next step.
Communication between the typewriters
Since our idea was all about unconventional communication, we decided to go all out and not use any wires or Wi-Fi to communicate between the two typewriters. Instead we decided to use light and morse code. We hacked a Table Lamp by putting a remote control from a TV inside of it. This remote control sent an "on" signal when the morse was "high" and an "off" signal when the morse was "low". We then used a photoresistor to detect the light from the lamp and convert it back into letters. The only thing missing was detecting uppercase letters. For this we used changed the morse code a bit, by sending a "high" signal for 3 seconds instead of 1 second.
→ Output Typewriter
The output typewriter was the most difficult part of the project. We had to figure out how to press the keys with enough force to leave a letter on the paper and still be very accurate when positioning the keys. We tried out different ways to do this. We tried using servos, but they were not fast enough. We tried using solenoids, but they were not accurate enough. In the end, we used three different stepper motors. Two of them were used to move the carriage in the X and Y axis and the third one was used to press the keys. We ended up relying on gravity to press the keys by having a very heavy metal rod attached to the stepper motor. The stepper motor would then pull the rod up and then let it fall, pressing the key. This worked very well and we were able to print out letters very accurately.
Still Have Questions?
Feel free to reach out to me! I'm always happy to talk about my work.