Open Colorimeter Documentation

Documentation page for the Open Colorimeter.

This is the documentation site for the Open Colorimeter. The Open Colorimeter is an open hardware science instrument for researchers, educators and hobbyists. It is used with colorimetric assays for environmental studies, water-quality monitoring, biochemistry and much more. This is a standalone, portable instrument which can be used either in the lab or measurements out in the field. Its is also great for hands-on & project-based curriculum. Listed below in the Table of Contents are links to pages describing the project designs, user guides and more.

Table of Contents


Open Colorimeter Introduction
The Open Colorimeter is an open hardware analytical tool for measurements that use colorimetric assays. A light sensor measures the amount of light (usually a specific wavelength) absorbed by the sample. Absorbance is related to concentration (Beer-Lambert Law) so the greater the concentration (colo…

Open Source Hardware & Software

Open Colorimeter 3D printed designs
Design methods We have been using FreeCAD for 3D hardware designs as described in this previous Newsletter. In this project we used the KiCad StepUp workbench to import a 3D model of the Sensor and LED PCBs from KiCad and the A2plus Workbench to create an assembly of the complete
Open Colorimeter Electronics
Electronics The Open Colorimeter uses STEMMA QT connectors. Communication with peripheral devices via I2C using 4-wire cables with JST SH connectors, such as Sparkfun Qwiic or Adafruit STEMMA QT, is rapidly becoming a standard on new development boards. This standardized cabling allows multiple s…
Open Colorimeter Firmware
The firmware for the Open Colorimeter is programmed using CircuitPython which is a version of the Python programming language designed to run on microcontrollers. CircuitPython is very easy to use and allows for extremely rapid firmware development. The Open Colorimeter will be shipped ready-to-use…

User Guides

Guide to getting started
The Open Colorimeter has the following features: * On/Off switch: An on-off switch will save battery power when not in use * Micro USB Port: You can power from the Micro USB port and it will also charge up the battery * Blank button: Use this with a blank reference (no signal)
Assembly guides
The Open Colorimeter is shipped fully-assembled and ready to use. However, we will be adding assembly guides to this page for users that want to learn how it is made, modify the unit, make their own from the open source design files or as a classroom teaching guide. The BOM
Optimizing the light sensor settings
The Open Colorimeter uses a TSL2591 light sensor, as described in the electronics page. In these notes we describe the light sensor settings and how to adjust them in order to achieve the best results. Open Colorimeter ElectronicsElectronics The Open Colorimeter uses STEMMA QT connectors. Communi…
Customizing configuration and calibration files
The Open Colorimeter ships pre-programmed with the circuitpython firmware. This page describes how to modify the firmware default settings to customize your instrument. Customizing the Open Colorimeter can make it more convenient to use, reduce setup time, help prevent user errors and ensure consist…
Installing/upgrading the firmware
In this set of notes we describe how to upgrade or reinstall the firmware on your Open Colorimeter. These instructions can be used whever there is a new firmware release that has new features that you would like to use. There are three steps: * Step One: Download and unzip the
Installing/upgrading CircuitPython and the bootloader
As new versions of CircuitPython come out you may want/need to upgrade the version of CircuitPython (or bootloader) running on your Open Colorimeter’s PyBadge. These notes describe how this can be done. Prior to upgrading the bootloader or version of CircuitPython make sure to copy any files you do…
Creating custom calibrations using oc-cal
In this set of notes we describe how to create custom calibrations for the Open Colorimeter using the command line program oc-cal. This program is part of the open-colorimeter-utils package which is available on PyPi (The Python Package Index). To use oc-cal you will need a working version of Pyt…
Creating custom calibrations using oc-calibration-app
In this set of notes we describe how to generate custom calibrations for the Open Colorimeter using a simple web app called the Open Colorimeter Calibrator. This app makes fitting your calibration data and generating the required .json file for your colorimeter quick and easy. The app is developed u…

Open Colorimeter Tests

Open Colorimeter Tests
Colorimeters are extremely flexible and easy to use lab instruments. They are great for developing new assays. Below are just some examples of how colorimeters can be used * Measuring water parameters such as water turbidity, chlorine content, pH, water hardness, phosphate content and more * Aqua…
Ammonia-API colorimetric assay
Colorimetric assay for measuring ammonia levels using API test kit. Range: 0-8ppm
Nitrate-API colorimetric assay
Colorimetric assay for measuring nitrate levels using API test kit. Range: 0-50ppm
Nitrite-API colorimetric assay
Colorimetric assay for measuring nitrite levels using API test kit. Range: 0-2ppm
Open Colorimeter: measuring blue food dye in sports drinks
Goal: Use the Open Colorimeter to experimentally calculate the molar extinction coefficient of FD&C Blue #1 Beer’s Law states that absorbance of a sample (Abs) depends on the molar concentration (c), light path length in centimeters (l), and molar extinction coefficient (ε) for the dissolved substa…

Purchase an Open Colorimeter from the Online Store

Open Colorimeter
The Open Colorimeter is a portable and customizable colorimeter for measuring absorbance, transmittance and concentration. The cuvette holder and enclosure are made from 3D-printed black nylon material and the electronics are programmed with open source firmware written in CircuitPython.

The Educational Colorimeter Kit (v1.0)
We initially designed the colorimeter as an Educational Kit in 2012 supported by Kickstarter backers. Educational colorimeter kitKit for making a programmable colorimeter for analytical chemistry and biochemistry labs & activities. Arduino compatible.Kickstarter Since our original design there hav…

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Documentation License

Documentation licensed under Creative Commons Attribution 4.0 International (CC BY 4.0).