Introduction:
At first I wanted to create a switch that would act as a detector if someone opened a journal or a personal diary but upon finding out that we are not allowed to use hands I changed my entire idea. I thought it would be most interesting to use a material that does not typically associate with conductive plate image in our mind. After all, we are all taught how it’s dangerous to play around electronics and water due to its conductive properties (it’s poor but better than air). Surely we could use it for something good. One such application could be the implementation of a very small sensor near all cups, specifically designed for use by blind individuals to detect when their cup is getting full. This project is just a physically bigger version of such project involving following materials:
Materials
- Piezoelectric speaker
- Jumper wires
- Aligator clips
- Arduino Board
- Power Bank
- Cup
- Water
Process
I decided to avoid using resistor at all since the audio produced by speaker wasn’t audible enough and would hardly activate by water touching the clips due to reduced voltage. I also decided to use salt mixed with water to improve conductivity and maximize the sound output. Realistically, if one were to transform this into a real project, we would be using cup integrated batteries, soldered electronics, built in sensor into the cup and any liquid substance. Even if conductivity is not terribly high, we could use a dedicated amplifier or a simple transistor.
At first I connected board to power-bank . I connected jumper wires to the board and alligator clips to jumper wires themselves. Piezoelectric speaker is part of the circuit and is directly mounted on bread board. The jumper wires leaving piezoelectric speaker are directly connected to alligator clips which are then connected to brim of the cup. When water is poured into a cup, at some point it touches the alligator clips and speaker makes highly audible buzz. This just so happens when water is about to overspill, providing the practical aspect of this project.
Reflection:
The idea of not using hands at all is a challenging one. I even thought about the aspect of indirect hand involvement. However, since it’s the rising water level that acts as a conductive plate and not a hand movement, I think conceptually it works just as well. The execution is pretty straightforward, with very simple design. Yet it tries to solve a realistic problem with minimum resources. In the future, this project could be expanded into an actual product, with more features, while trying to seamlessly integrate design into the cup.