DIY Spectrophotometer using Arduino

Spectrophotometery is a quantitative measurement of the transmission properties of a chemical substance as a function of wavelength, and the device used for this purpose is known as Spectrophotometer. It operates by passing a beam of light through a sample and measuring the intensity of light reaching a detector through the sample. This Instructable describes an Arduino controlled DIY Spectrophotometer made by two undergraduate biochemistry students-Peter Elphick and Ed Tye, for their final-year lab project.

Arduino powered Spectrophotometer

Arduino powered Spectrophotometer

We wanted to make a spectrophotometer that would measure the concentration of a dye called OPD; a common dye in biological assay kits. In addition to reading the absorbance of the samples, we wanted to make a spectrophotometer that worked with 96-wellmicroplates. These are disposable, multi-sample plastic dishes and are the backbone of assays in academic and pharma bioscience labs. They hold 96 samples of up to 0.35mL, arranged in a grid. Pharma labs like them because they lend themselves to robotic handling and high-throughput assays.

We reckon that the final machine cost about £500 ($750), although a lot of that could be saved if you machine your own frame.


GPS based car locator

Keep forgetting where you have parked your car in the parking lot? This Arduino-based car locator uses GPS to remember where you park with just the push of a button and later tells you how far you are from it and in what direction.

The GPS continuously reads the latitude and longitude of the CarTracker. When the button is pressed, the coordinates are saved to the EEPROM. E.g., this would be the location of your car.

Now, let’s say you walk out of a store and are looking for your car. Power up the CarTracker. Do not push button. The GPS will read the coordinates of the store and will calculate distance and direction from there to the stored location (of the car). The compass will orient the display so the display will point to the car and will display the distance.


GPS car locator

GPS car locator

Making a high-altitude balloon cam

Ray Visser posted an instructable on making a simple high-altitude balloon cam with minimal payload containing a smartphone to text its GPS location and a Canon Powershot digital camera to take pictures.

High-altitude ballooning, or HAB, involves sending a payload of cameras, scientific instruments, or other items on a journey into the stratosphere, strapped to a weather balloon. When the balloon bursts, a parachute brings the payload gently back down, where it (and your data/photos/freeze-dried food) can be recovered!

Most HAB systems are electronically complex, so we wanted to drastically simplify it. Our payload is only a smartphone designed to text its GPS location (for accurate recovery) and a Canon Powershot digital camera set to take a photo every few seconds until its memory is full.

Read on to see how we built it! Ours is far from the best design, and hasn’t yet been field-tested, but the instruments work well enough. This is designed more as a starting point and a collection of tips.

DIY hot-ba

DIY high-altitude balloon camera

RGB Graphic Equalizer driven by ESP8266

Amir Avni has shared the details of his cool RGB graphic equalizer build, which is controlled by the ESP8266 hardware programmed with the NodeMCU firmware. The RGB LED strings are controlled through WS2812, while the equalizer colors are chosen through a Web interface over Wifi.

RGB graphical equilizer

RGB graphical equilizer

Two weeks ago I got my ESP8266 Version 12, which is a new version of the ESP8266 micro-controller with more GPIOs, so it seems some nice things can be done with it. If you haven’t heard of the ESP8266 check this older postfrom the blog. Also, I got the MSGEQ7 chip, which is a chip that outputs an analog equalizer from a sound signal. I was looking for a fun project to do with those two items, one which can help me also to learn LUA script, the language that is used to program the ESP8266. Finally, I’ve created this project: An equalizer display controlled by ESP8266 with the NodeMCU firmware, where the equalizer colors are controlled via WiFi. Check the video:

Introducing Easy Pulse Plugin: A breadboard friendly and Arduino/chipKIT compatible pulse sensor

Today we are happy to announce the release of a new addition to our Easy Pulse Sensor series named Easy Pulse Plugin. Like its predecessors, the original Easy Pulse and Easy Pulse V1.1, Easy Pulse Plugin also operates on the principle of Photoplethysmography, which is an optical technique of sensing blood volume changes in tissues by illuminating the skin surface with a light source and measuring the reflected or transmitted light using a photodetector. The photodetector output contains the cardiovascular pulse wave, which is synchronized with the beating of the heart. Easy Pulse Plugin provides all necessary instrumentation and amplification on board to detect the cardiovascular pulse signal from the fingertip. The most important characteristics of Easy Pulse Plugin is that it can be easily plugged into the left headers of Arduino Uno (or its compatible clone) board for easy interfacing, and the analog pulse signal can be fed to either A0 or A1 analog input through a 2-pin jumper selection. You can buy this sensor at our Tindie Store.

Easy Pulse Plugin module

Easy Pulse Plugin module


Easy Pulse Plugin is easy to interface to an Arduino Board

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