Making Capacitive Touch Sensors With Pencil And Paper

May 27, 2012 by Mike Nathan 6 Comments

capacitive-touch-sensor

There are few things more frustrating than being in the middle of working on a project and realizing that you are missing some crucial component that ties the whole thing together. According to Murphy’s Law, this sort of thing will only happen when parts are completely impossible to procure.

If you’re ever hunting for a touch sensor but can’t get your hands on one, [Alan Chatham’s] tutorial on simple DIY capacitive touch sensors might be just what you need to keep things moving along.

[Alan’s] sensors rely on the conductive properties of graphite, which is easily found in just about any pencil on the market. The sensors are created by simply drawing on a piece of paper with a pencil, then wiring the images or text up to your favorite microcontroller via some paperclips and a couple of resistors.

Paper and pencil might not make for the most durable means of input, but we’re pretty sure that [Alan’s] capacitive touch sensors would be very helpful in a pinch. He doesn’t have video of the sensors in action just yet, though he says he’ll put something together here shortly.

Wicked Use Of HTML5 To Display Sensor Data

October 25, 2011 by Mike Szczys 33 Comments

This project shows you one possible way to use HTML5 to fully integrate sensor data from a microcontroller into our technological lives. Now, when we saw this tip come through our inbox we thought it would be an interesting example to learn from but we weren’t ready for how truly cool the setup is. Take a look at the video after the break and you’ll see that scanning the QR code on the project box will immediately start a 10ms resolution live stream of the accelerometer data. Furthermore, the browser page that the phone loads allows you to send what you’re currently viewing to the main frame of a browser running on a different computer with the touch of a button. In this way you can build a dashboard of streaming sensor data. Talk about the future of home automation. Imagine a QR code on your thermostat that allows you gain access to your home’s heating, air conditioning, humidifier, and water heater performance and controls just by snapping a pic? The sky’s the limit on this one so let us know what you’d use it for by leaving a comment.

In this case an mbed microcontroller is handling the data acquisition and pushing that to a server via a WiFly module using the WebSockets library. This data is pushed in the form of a JSON packet which is distributed by the server as a data stream. Clients can access it via a browser through a page that makes use of JavaScript.

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Logging Bubble Frequency And Pressure In Your Fermenter

October 24, 2011 by Mike Szczys 21 Comments

In an attempt to add technology to his brewing process [hpux735] build a sensor rig that monitors bubbles and pressure during fermentation. What does this have to do with brewing great beer? We’re not sure and neither is [hpux735], but he’s got some preliminary readings to spark your imagination.

The bubble sensor itself was inspired by a SparkFun Tutorial where fermenting wine was monitored with a data logger. It uses an optical gate to detect the passage of air. But the goal here was to combine bubble frequency with internal pressure measurements to calculate how much CO2 is being vented. Perhaps it would be possible to get an idea of how close the batch is to completion based on those calculations. A hole was drilled into the fermenter side of an airlock to take these pressure readings.

This actually works quite well during secondary fermentation when the bubble frequency is quite slow. The hardware is able to discern a pressure difference before and after a bubble has passed the lock. Unfortunately the system breaks down during the vigorous bubbling that takes place soon after pitching yeast. See a few bubble-counting clips in the video after the break.

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TSC230 Color Light-to-Frequency Module

September 8, 2011 by Mike Szczys 5 Comments

ElecFreaks is selling a new color sensing module based on the TSC230 sensor. They’ve posted a demonstration using an Arduino that shows off what this sensor is capable of. The module includes four white LEDs which give a baseline of light to help normalize readings when reflected off of differently colored surfaces. The white balance of the sensor needs to calibrated in software in order to ensure accurate readings, but once that’s done you’ll be cable to pull RGB values off of whatever you put in front of the sensor.

What a nice addition to sorting machines like this LEGO sorter. Of course you can do something like this yourself using an RGB LED as a detector, but the TSC230 is extremely sensitive and should be quite reliable in comparison. They’re selling the module for $15, a price point that’s hard to beat if you need precise color detection in your next project. A colored token reader for your MAME cabinet perhaps?

Paper Accelerometers For Pennies In The Works

February 12, 2011 by Mike Szczys 20 Comments

Cheap paper accelerometers? Put us down for a dozen to start. They’re not quite ready for mass production yet but it looks like they’re on the way.

[George Whitesides] led a team to develop the new technology that uses simple manufacturing methods to produce the sensor seen above. Graphite and silver inks were screen printed onto heavy paper. The single limb sticking out from the body of the sensor is a separate piece of paper that bends the carbon area when force is applied. This changes the carbon’s resistance which is measured using a Wheatstone bridge constructed by gluing resistors to the device.

It sounds unsophisticated compared to most of the accelerometer modules we’re used to, but if you need a sensor that detects sudden motion this sounds like the perfect part. Now who wants to be the first person to replicate this in their basement?

[Thanks Fabien]

Today’s Arduino Minute

February 10, 2011 by James Munns 15 Comments

Sometimes projects are vast, complicated, and complex. Other times projects are a bit more on the simple. Today we thought we would share a couple projects with something in common that may be familiar sounding to the more experienced crowd, but may inspire a few readers new to the world of microcontrollers.

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Christmas Tree Low-water Monitor

December 8, 2010 by Mike Szczys 24 Comments

The end of the year is rapidly approaching and there’s a good chance you have a slowly dying tree in your living room. Help it hold on a little longer by using [Eric Ayars’] Christmas Tree water monitor. He’s built a sensor out of a piece of strip board. Three bus strips on the board allow for a variety of alerts. When all three are submerged everything is ok. When the two longer traces are still under water but the third is not an LED will blink to let you know it’s time. If you don’t pay attention and there’s no water left, a piezo buzzer makes noise until you add water (or the coin cell runs out of juice).

This project centers around an ATtiny85 that [Eric] programmed using an Arduino, one of the methods we covered in our AVR Programming Tutorial. But if this simple circuit isn’t high-tech enough for you, we saw a similar method last year that will send an alert to your iPhone.