Connecting Inexpensive pH Probes with Ease

 

We’ve mentioned that it’s hard to find someone not selling or crowd funding something at Maker Faire. Despite the fact that [Ryan Edwards] is selling his boards, we still got the feeling that he’s a hacker who is selling just to make sure the idea he had is available for other hackers to use. He showed us his interface boards for inexpensive pH probes.

Since we’re always looking for more chemistry hacks to run, it was nice to hear [Ryan's] description on how these probes (which can be had for around $9 on eBay) actually work. It turns out it’s all about salt. When it comes to the electronics, the board provides a connector for the probe on one edge, and pins for voltage, ground, and I2C on another. Rig this up with your microcontroller of choice and you’ll be building your own automatic pool doser, fish tank minder, or one of a multitude of food-related hacks.

Head on over to Sparky’s Widgets to see a few other demo applications.

Automated pH Control

pH Controller

Controlling the pH level of a solution is usually a tedious task. Adding an acid or base to the solution will change the pH, but manually monitoring the levels and adding the correct amount isn’t fun. [Reza] rigged up an automated pH controller to keep a solution’s pH steady.

The build uses an Arduino with a LCD shield, screw terminal shields, and [Reza]‘s own pH shield attached. A peristaltic pump is used to pump the pH down acid into the solution. This type of pump isolates the fluid from the pump parts, preventing contamination of the solution. The pump is controlled using a PowerSwitch Tail, allowing the Arduino to control the flow of fluid.

An Omega pH probe is used to read the pH level. [Reza]‘s open source firmware has support for calibrating the probe to ensure accurate readings. Once it’s set up, the screen displays the pH level and the current state of the system. The pump is enabled when the pH rises out of the desired range.

After the break, check out a video walk through of the device.

[Read more...]

DIY Science – Acid/Base Natural Indicators

natural-indicators

Nearly everything at [HAD] is at least based on science in some way or another. If, however, you would like to do some actual scientific experiments with stuff around the house, [Observationsblog] might be for you.

The particular posts that [Ken] wrote in to tell us about were all about acids, bases, and natural indicators. In his first post he goes over some definitions of acids, bases, and what pH exactly means. A good refresher for those that have forgotten some of their high school (or college) chemistry classes.

The other two posts have to do with making your own natural acid/base indicators. The first is called Anthocyanin, and can be extracted from Red Cabbage.  Quite specific directions can be found here. Similar directions can be found to turn the Indian spice of [Turmeric] into an indicator as well. Although these concepts probably won’t help build your next robot, they could easily be copied inspire young minds for a great science fair project!

Wine cask sensor suite

As part of his Master’s dissertation [Salvador Faria] built a sensor suite for wine monitoring. He needed to develop a method of tracking data inside the wine cask during the vinification process. What he came up with eclipses the wine cellar temperature monitors we’ve seen before.

He picked up pH, temperature, carbon dioxide, alcohol, and relative humidity sensors from familiar vendors like Seeed, Parallax, and SparkFun. His original idea was to develop a floating probe that housed the entire package but he had quite a bit of trouble getting everything inside and maintaining buoyancy. The solution was a two-part probe; the stationary portion seen mounted on top of the cask houses the microcontroller, RF 433 MHz transmitter, and the gas sensors. Tethered to that is a floating probe that measures pH and temperature. Data is sent over radio frequency to an HTTP POST server every minute.

Arduino pH meter

phduino_v02_PIC_0050

[Carlos] sent us his project that uses an Arduino as a pH meter. In order to sense the acidity or alkalinity of a solution, a glass electrode is connected to the ADC of the Arduino through a fairly complicated calibration, amplification, and filtering circuit. Admittedly, it may not be cheaper or as accurate as some commercial models, but it is an open project and can be interfaced with a computer via USB.

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