Public Lab is an open community which collaboratively develops accessible, open source, Do-It-Yourself technologies for investigating local environmental health and justice issues.
Coqui conductivity sensor
## What Does It Do?
**The Coqui: a simple device to read a sensor via an audible tone.** We're exploring using audio frequencies to convey sensor readings -- like a modem, but even simpler -- in order to make sensor readings more accessible for people (or to enable data transmission over ubiquitous audio jacks on PCs and smartphones).
## Latest version
The [latest and simplest version of the Coqui](/notes/warren/03-01-2019/build-a-sound-generating-coqui-conductivity-sensor) can be seen in the following images. This version differs from [the previous](/notes/ashkaya/09-17-2016/build-a-coqui-a-simple-water-conductivity-sensor) in a few ways:
* smaller, cheaper circuitboard (breadboard)
* fewer wires
* flatter wires which make it easier to see the circuit
However, the circuit is fundamentally the same! Click these images to enlarge:
## Assemble the Coqui
Here are a few guides to building different versions of the Coqui:
## Coqui versions
The Coqui has been refined, remixed, and modified plenty over the years.
## Modify the Coqui
## Do something with the Coqui
Once you've built a Coqui, here are a few things you can do with it:
Add an activity or request an activity guide you don't see listed
## Frequently Asked Questions
A Coqui is a simple, inexpensive, open source device that generates an audible tone that is based on any electric resistance-based measurement. For example, a Coqui can measure:
* conductivity of liquids
* ambient light
## Build a Coqui
Instructions on the breadboard-based "BBv1.0" edition of the Coqui can be found here:
- The github repo for a more permanent printed circuit board version of the coqui is [here](https://github.com/OpenWaterProject/coqui)
The Coquí is a circuit that allows you to 'hear' the readings from various sensors. Once the Coquí is assembled, you'll be able to 'hear' the conductivity of a solution, the temperature of a room, or the color of a pH test strip.
The design was named (onomatopeically) after the several species of small frogs which have a loud, distinctive call at night.
### Demo Coqui applications
- [Testing the conductivity of a solution](http://publiclab.org/notes/donblair/09-30-2014/coqui-bbv1-0-testing-conductivity-of-a-solution):
- [Reacting to an LED with sound](http://publiclab.org/notes/donblair/09-30-2014/coqui-bbv1-0-reacting-to-an-led-with-sound):
- [Assessing ambient light levels](http://publiclab.org/notes/donblair/09-30-2014/coqui-bbv1-0-assessing-ambient-light-with-a-photoresistor):
- [Assessing temperature with a thermistor](http://publiclab.org/notes/donblair/09-30-2014/coqui-bbv1-0-using-a-thermistor-as-a-temperature-probe):
- [Sending water quality voicemails with a coqui using vojo.com](http://publiclab.org/notes/donblair/09-10-2014/water-quality-coqui-voicemails):
### Building your own Coqui
- [Coqui BBv1.0](http://publiclab.org/notes/donblair/09-30-2014/coqui-bbv1-0): a breadboarded version of the Coqui
### Building Coqui sensors
- Making a conductivity probe from a [bottle cap and two metal screws](http://publiclab.org/notes/donblair/09-30-2014/making-a-diy-conductivity-probe-from-a-water-bottle-and-metal-screws)
## Parts list
See the initial parts list here: #13459 and #11209 for a DigiKey shopping cart link at $19 per kit. And @kanarinka mentions:
> there are a couple other things that are helpful to have that are not shown (like the probe made from the top of a water bottle with two screws in it and alligator clips to attach that to the breadboard)
Scans of an invoice from DigiKey: