Open Colorimeter Product Guide

Open Colorimeter Product Guide

This is the documentation site for the Open Colorimeter and new variants including the Multi-Channel Colorimeter, UV Open Colorimeter and Open Colorimeter Plus. Instruments in the Open Colorimeter product line are open hardware science designs with wide-ranging applications. They are standalone, portable instruments which can be used either in the lab, classroom or for measurements out in the field.

Listed below are user guides and tutorials as well as documentation pages for the hardware designs and CircuitPython firmware.

We will be updating and adding to this documentation site over time. However, if you can't find the information you need in the Product Guide please contact us at or fill out our contact form.

Table of Contents


Open Colorimeter Product Line Overview
There are several versions of the Open Colorimeter available. The main differences between them are the light sensor used and it’s positioning in respect to the LED light source. The LED light source is also highly customizable. We have a wide-selection of LED wavelengths in the UV, visible and IR
Open Colorimeter Introduction
Colorimeters are extremely flexible and easy to use lab instruments. Below are just some examples of how colorimeters are used: * Water quality testing: there are a wealth of colorimetric assays for measuring water parameters such as water turbidity, chlorine content, pH, water hardness, phosphate…
Getting Started: Installing a 3.7V Lithium Ion Battery
The Open Colorimeter can be powered by USB or a 3.7V lithium ion battery. To use the Open Colorimeter without a battery, simply plug in the USB cable for power. However, we recommend using a battery as the instrument works best as a portable device. Currently we are not
Getting Started: Basic Operation & Menu Navigation
These instructions below apply to all variants of the Open Colorimeter. 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

Open Colorimeter Tests & Tutorials

Open Colorimeter Cuvettes
The Open Colorimeter products ship with a small pack of cuvettes to get you started using the instrument. The type of cuvette included depends on the instrument: * Open Colorimeter & Multichannel Open Colorimeter: Pack of 6 BrandTech macro and semi-micro cuvettes (3 of each) * UV Open Colorimeter: Pack of 4 BrandTech
Open Colorimeter Tests
Colorimeters are extremely flexible and easy to use lab instruments. Below are just some examples of how colorimeters are used: * Water quality testing: there are a wealth of colorimetric assays for measuring water parameters such as water turbidity, chlorine content, pH, water hardness, phosphate…
Open Colorimeter Tutorials - IO Rodeo Blog

Open Source Hardware

3D printed cuvette holder and enclosure
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
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 sensors to be connected to the development board without any soldering. By using these standardized
Open Colorimeter LED Boards
We have designed a series of LED boards which can be used to customize any of the Open Colorimeter products. These include UV LEDs for use with the UV Open Colorimeter, a series of visible and IR LED boards. All of the LED boards are designed with these same features
Light Sensor Boards
As mentioned in the Introduction, the different variants use different light sensor boards. Here we will go into these sensors in more detail. Some similarities we won’t go into deatil but all of these light sensors have the same form factor and standard 4-pin JST SH connectors (also called STEMMA

Open Source Firmware

Open Colorimeter CircuitPython Firmware
The Open Colorimeter ships ready-to-use and pre-programmed with firmware, so you do not need to be a programmer to use it! 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
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
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…
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…
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…

Calibration Files and Custom Calibration Tools

Overview of Open Colorimeter calibration files
This page gives some more information on the calibrations.json file which is used to load custom calibrations onto the Open Colorimeter. This file contains calibration data for measurements and the individual entries in this file become the tests which are displayed in the Open Colorimeter’s menu. They are displayed
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 oc-calibration-app. This app makes fitting your calibration data and generating the required .json file for your colorimeter quick and easy. The app is developed using the…

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 Documentation for the original Educ…

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Documentation License

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