Friday, November 20, 2009

MicroRax Construction Kits

For anyone interested in incorporating dreams and ideas to reality, consider this recently released construction set called MicroRax. MicroRAX is a set of parts that can easily be used to assemble your latest project. It reminds me of the erector sets I used to play with as a child but much more. I wish I had had something as cool as this when I was younger.

The foundation of the kits consists of 6063-T6 aluminum t-slot profiles and nut plates that slide within the slot so that the various joints can be used to connect another profile. Connecting one of joints to the nut plate is done by using the 18-8 stainless steel, M3 x 5mm screws. There are "L" style joints, corner style joints, truss style joints and a 90 degree joining bracket. Getting started is fast and easy. After cutting your profiles to whatever various sizes you might want, the only tool you'll need is the included hex key to tighten down the screws.

I wasn't playing with my free samples very long before ordering the "Pro" kit, which includes 7 90cm profiles and enough of the joints and screws to turn several ideas into reality. A hex key and vinyl caps are also included. I've been working with my kit for almost a week now, trying out the various joints, making boxes, frames and containers. When I'm all done with an idea, I can disassemble it down to the pieces and start over. MicroRax makes it simple to go from idea to project to an actual device quickly and easily. STL files are available at Thingiverse for the profiles to include in CAD programs.

I looked through several of the blog posts at MAKE Magazine some of the other maker type sites and see where building my own enclosure for many of the kits available would not only be less expensive but by using frames and enclosures built using MicroRax., when the project has outlasted its usefulness and is sitting in a box in a corner with various electronic parts already removed for newer projects, the mechanical parts can now be disassembled and recycled for my latest idea also.

In the coming weeks, I will be posting some of my assemblies, frames and containers as examples of what the kits can do. The Starter kit runs $89.00 and the Pro kit is $192.00. I am more than happy with the variety and number of parts in the Pro kit and look forward to exploring the possibilities. Stay tuned.

I was not paid or compensated by MicroRAX for this review. While I did receive a free sample, this was not special treatment, as anyone can request the sample.

Saturday, November 14, 2009

Digi Smart Plug

One of the interesting topics discussed yesterday during the Digi Webinar is a new product called the SmartPlug. It looks like one of the network extenders or routers. It includes an ambient light sensor but also a switch that allows a light or some other appliance to be plugged into it and controlled. In addition to being able to turn the appliance 'on' and 'off,' it will give a status of the appliance and also the amount of current the appliance is drawing, when 'on.' New drivers have been added to the DIA system so the Smart Plug can be controlled. See the web page above displaying the current, power and the on/off switch.

I ordered two of the Smart Plugs and when they arrive I will try them out and post additional information on them. One of my goals in my project for the house is to be able to control an air conditioning/heating duct and be able to close off one of the bedrooms during the day and force the cooler air to an area of the house that is occupied while having it go back to normal in the evening. The Smart Plug would be great at this as it could not only be controlled manually but have it flip the switch automatically based on a particular temperature or time of the day.

There were other topics discussed during the webinar and I will share those in the next few posts.

Sunday, November 8, 2009

Digi Webinar

For those of you interested in the XBee controllers and radios, there is a free Webinar on Wednesday, 11 November at 1:00PM - 2:00PM EST. Key Product Focus will be on XBee, ConnectPort X, iDigi Dia, iDigi platform. I will be attending and taking notes.

Away Due to Health Issues

For the past few weeks I have had some personal health issues that have prevented me from keeping up with my projects, including posting to this blog. Thankfully I have worked through the issues and am feeling better and am catching up with all of my projects. My goal is to start posting and due a minimum of one post per day for the next month, with the possible exception of Thanksgiving Day. I am going through my notes and will either start posting later today or tomorrow. I will also answer any outstanding questions from the comments section. There have been lots of cool things going on over the last few weeks that I haven't been able to participate in but will start jumping in immediately.

Sunday, October 25, 2009

Energy Harvesters

Energy harvesting, according to Wikipedia, "is the process by which energy is derived from external sources (e.g., solar power, thermal energy, wind energy, salinity gradients, and kinetic energy), captured, and stored." So any solar, wind, etc. system that stores energy in batteries or capacitors would be considered an energy harvester. What I am going to focus on are much smaller energy harvesters that can be used to power microControllers, sensors and wireless radios, like the ZigBee types of transceivers.

Assembled energy harvesters, in my opinion, are prohibitively expensive. If you click on any of the Google ads that occasionally appear on this site you will find they run $300-$500, and to purchase a development kit they are over $700. The military is keenly interested in energy harvesters and it seems they are priced for a military budget. For the rest of us, however, there are alternatives.

Basically an energy harvester is nothing more than a source that can collect energy (i.e. solar, wind) and store it for continued use. Both batteries and super capacitors can be used as a storage medium and certain types of DC-DC converters are perfect for this type of use.

Looking at figure 1, the energy collector is a piezoelectric vibration sensor that picks up vibrations and outputs a small AC signal. In its place one could a solar cell, a Peltier Cell or basically anything that can produce an AC or DC voltage, perferably higher than .7 Volts. The four diodes rectify the signal and turn it from AC to DC. In this circuit a Super Capacitor used, with the BZX85-C2V7 diode
in place to prevent voltage across the super-cap from increasing beyond the maximum voltage rating.

The controller of the circuit is a Max1675 compact, high-efficiency, step-up DC-DC converters. The important features of the converter is that it will continue to charge a battery or super-cap as long as the voltage is .7 Volts or above and it can be easily configured to output 5 Volts. In the figure 1 circuit, the FB pin is connected to the OUT pin. By connecting the FB pin to GND the output is 5 Volts.
In a 5 Volt circuit, the Zener diode would need to be replaced with one that is 5 Volts (TZX5V1B-TAP) and the super-cap would need to be replaced with a higher voltage one or with an appropriate battery.

The Max1675 converter is primarily designed for cell phones, PDAs, pagers, etc. so running at 3.3V & 5V is typical. The package only comes in SMT type so for those of you, like me, that have bifocals it will be tricky to solder.

Preview to Come

I recently inquired about receiving a sample from the MicroRAX T-Slot building kit. I was quite surprised to get a call from one of the co-owners of the company, Chris Burrows, who gave me a quick rundown of the company and the products. The kits are a "light weight minature T-Slot building kit" which can be used for engineering mock-ups or any type of maker projects. Once I receive the samples I will post about them and most likely order one of the kits. Stay tuned because I think these kits are something many of us will want as part of our design tool box.

Monday, September 21, 2009


More and more parts are SMD type package only and is just to hard to manually solder, with my old age eyes. Has anyone out there heard of any DIY methods for soldering the SMD type packages to boards? Sparkfun puts out a nice breakout board for 6 pin SOT-23-5 so if there was an easy way to solder the component to the breakout board, it could then be worked with in a normal fashion.

Anyone have any ideas?

Wednesday, September 16, 2009

What I'm Doing

Since the link between me and my readers (that would be you folks) is I post--you read, with no feedback I have tended to not post anything until I have some sort of closure. Projects I'm working on but have not finished are:

-Sensor array consisting of a temperature sensor, light sensor, LED along with a uController & XBee to measure light and temperature of a room and provide light based on the brightness of the room.

-Designing the database schema for sensors and controllers

-Evaluating SMD components for sensors like temperature and humidity and how I can solder them to a board without spending a tone of money.

-Evaluating a few proximity sensors to determine which work best and if I can profile them and make it so they can recognize the differences between people for recognition purposes.

-Designing LED light fixtures that could be hand-held yet provide enough light to actually provide light to a room (equivalent of a 40 watt incandescent bulb or more)

-Writing code to interface sensor arrays to the main computer.

-Writing software to remotely control and read the sensors

The reason for working several projects at a time and not finishing one before moving on to another is mostly due to ordering parts, waiting for them to arrive, altering design, research, etc. Since I don't have a brain trust handy and you folks won't participate, it's just me. that's fine and all it just takes me long to finish.

So once I have a project finished I will put together a pot about it and also put together some How-To's so you can build one on your own without all of the design alteration and research. Until then, I will provide status reports when progress has been made.

I am going to try this approach and see if it lends itself to more consist writing.


PS I've decided that my readers must really love my writing otherwise they would be providing harsh comments about my poor grammar and spelling, well poor grammar since this blogging software does provide spell check.

Tuesday, September 1, 2009

Comments, Spam, etc.

I have adjusted the permissions of the blog so anyone can leave a comment without signing in or having either a Google or OpenID. Bloggers typically jump for joy when their blog is appropriately littered with comments, either positive or negative. While I don't measure my self-worth on the number of comments I receive, I do appreciate the feedback when it adds to the discussion.

So feel free to comment away until the spammers us, which will force me to lock it down.

Sunday, August 30, 2009

Sensor Arrays, Ctd.

Humidity sensors are typically more expensive than temperature sensors and are more complex to design/build a circuit around. As the price goes up, the fewer additional parts are needed but once the price gets beyond the $50 range, I'm not that interested. For about fifteen dollars and about five more in additional parts, a decent humidity sensor can be built. I plan to do some mapping in my home but I am guessing that there are probably not pockets of high or low humidity in my house and having 2-3 max humidity sensors will be plenty.

A few weeks ago I was reading and article in MAKE magazine about a guys who wanted to lower his clothes dryer electricity bill so he sought to use hot air from outside or the attic. I thought it would be a cool idea if you lived in a place with dry heat but don't think it would be feasible here in Florida. At some point I might try it just to see if really hot humid air could successfully contribute to lowering drying time. I think the key is to find a way to take the water out of the air quickly.

Any ideas?

Sensor Arrays

For my home automation project I am designing some sensor arrays to collect various type of data. Examples of sensor types include temperature, humidity, light intensity, proximity, sound and possibly a RFID reader. Each sensor array will be connected to an XBee Series 2 transceiver in order to be linked to the wireless network. When possible, a sensor will be designed to use an energy harvester which will allow the sensor array to run for long periods of time between charges.

An example of a typical array will be one with a temperature and light intensity sensor included in the circuit. Placing temp/light sensor arrays throughout the house will allow me to track hot and cold spots and help determine the best way to keep the house cool while using the least amount of energy. Living in Florida, it is rare to be concerned about it being too cold in the house or how to keep the house warm enough to fight off frostbite.

Typically in my house the master bedroom stays about 3-5 degrees cooler than the rest of the house. This is perfect at night as my wife likes to sleep in a cooler room. However once we are up in the morning and either at work or working at home, very little time is spent in the master bedroom or bath. If the cold air being delivered to the bedroom could be channeled to the living room or the office, it would keep the part of the house being utilized cooler without lowering the thermostat.

Using the light intensity sensors will help map out the brightness of the rooms being used at particular times of the day and determine which areas need additional light as it gets later in the day. What I hope to accomplish is to inexpensively add light to the kitchen/dining room by building lights using 20 Watt LEDs that would dim/brighten based on the amount of light needed. A 20 Watt LED has approximately 1000 lumens, which in incandescent wattage amounts is approximately 100+ Watts. A couple of LEDs could keep a high ceiling, open area nice and bright throughout the day and night.

Energy Harvesters

Energy Harvesters are starting to be mentioned and talked about by some of the technical e-zines. Basically energy harvesters consist of a circuit to keep a battery or super capacitor charged by collecting small amounts of energy using a transducer. Typically the energy harvester is charging a sensor (i.e. temperature, humidity, light, proximity). Transducers can be photovoltaic cells but since many of the sensors are indoors the solar cell needs to be very sensitive. Another option that might be usable is a piezoelectric sound transducer, which converts vibrations to electricity.

The problem I have with all of the examples I've seen is that they are cost prohibitive for what they are trying to accomplish and to the people who would take them and experiment with them. $35.00 for a semi-working energy harvester and over a hundred for an evaluation kit defeats the purpose of getting the technology out there and working with it.

I am in the process of building a small energy harvester using a piezo-electric transducer to power a wireless temperature sensor. I still have a few more parts to procure and some calculations to work out but, if successful, the time between backup charges of the super capacitor could be significantly extended. The most expensive portion of my project has been the shipping charges because I have been impatient in waiting for the parts. The DC-DC Step-Up Voltage Regulator was a little over five dollars in quantities of one and the rest of the parts are off the shelf capacitors, resistors and some low reverse leakage diodes.

Once I have all the parts, assemble them and test it out I will publish the results (good or bad). Energy harvesters have the potential to allow low current applications to run months, years or effectively forever without the need for battery replacement.

More on this subject.

Speed Blogging

While waiting for parts, tools, time to spend and getting my brain working to finish the projects I'm working on before blogging about them I'm going to do some speed blogging where I talk about the projects and some other topics on my mind. Most of the topics will be related to microcontrollers, XBee radios and Home Automation but occasionally I will veer off the path with a rant or two.

Any feedback is welcome. I know you're out there reading so drop a comment or two to let me know you're alive.

Saturday, August 8, 2009

Topic Requests

The blog will start picking up with both short and longer posts on a variety of subjects along the lines of home automation, alternative energy, smart homes and how to design and build items where the costs are not prohibitive.

If you have any ideas and/or requests that you would like for me to write about, feel free to let me know in the comment section or my email address in my profile.

Tuesday, July 28, 2009

Python Bootcamp - Day 1

Boot camp accommodations are nice, class size is small (four total) and the instructor is well informed and can answer questions outside of the study material. So far I would say I made the correct decision, at least when it comes to learning. My hotel selection was a crash-n-burn but more on that subject later.

The only downside to the class is that it is taught on Windows' computers but the instructor is familiar with Linux and shares differences (installation, path set up, etc.) when they come up. He uses a Mac so personally he has seen the light.

No one has had to drop and give the instructor 20 so we must be keeping up with expectations.

Thursday, July 23, 2009

Python Bootcamp

Next week I will be attending the Open Technology Group Python Bootcamp. Training will consist of 5 days and is tailored for programmers with experience in other languages and want to learn the fundamentals of Python. I have been playing with Python for several months but had no real project in mind so I would read a Python article or book after work, try out some of the examples and then lose track due to responsibilities at work. I wanted the opportunity to immerse myself into the fundamentals without interruptions and have it my main focus for the week. Also I have found in the past when I have attended developer training sessions, the real learning came from the tips and tricks from the instructor or the discussions that started from students' questions.

If I have time I will post some thoughts next week on how the classes progress but otherwise I will give a full account when I return on 1 August.

Friday, July 17, 2009

Adding to the Brain Trust

I recently joined the Tampa Bay Microcontrollers and Robotics group to share ideas in using the Arduino (and other) microcontrollers. The group was only started recently but already we have had a lively discussion on high brightness LED circuits and members have volunteered to combine orders to some of the stores that sell microcontroller accessories, sensors and components. We didn't even have to email our order in, a google doc spreadsheet was created for either vendor and we filled in the part number description, quantity, price. When the order was placed and it wa time to pay, we did it using PayPal.

During our next meeting we will all share our current projects, talking up the high points and asking for help on any problem areas. There are lots of local groups out there when it comes to microcontrollers and especially robotitics. I recommend getting involved and sharing ideas. We even have an additional group to explore the idea of creating a new programming language and compiler for the Arduino.

While I wouldn't trade my electronic access to discussions, information and searching for anything it is nice to sit down and engage in face-to-face discussion while having a nice breakfast (we meet at a local restaurant that has a group room with wireless access).

It's easy to do. Here is a link for Meetup, a way to find groups you might be interested in or to start a group that doesn't currently exist and ask for interested people to join.

Wednesday, July 15, 2009

Arduino Duemilanove

I'm in the stage of planning on how many sensors and what types I will use throughout the house. While Digi provides some basic sensors like temperature, humidity, brightness and some others there will always be a need for something specific. In addition to sensors there is also the ability to send out commands to control things like lights, fans, entertainment equipment, etc. To build my own sensors and control devices I picked up an Arduino Duemilanove, which is the latest revision of the basic Arduino USB board. It has 14 digital input/output pins, 6 analog pins, 16 MHz clock speed and 32K of Flash memory for holding programs. I've been playing with the IDE for writing programs, which are referred to as 'sketches.' So far I have been able to turn LEDs on and off, read values from input sensors like photocells and send data back to the computer via the USB connection.

There is a google code project called python-on-a-chip with a goal to allow a subset of the Python language to run on microcontrollers without an OS. I hope to be able to take my Arduino and install the PyMite virtual machine and be able to run some Python routines on it. How cool would that be???

Sunday, July 12, 2009

Digi Wireless Design Contest

Digi is sponsoring a Wireless Design Contest. The way it works is you purchase one of three of their Wireless Starter Kits, design a solution and submit. There are quarterly winners and the top prize is $7,500.00. I bought one of the kits before I knew about the contest and enjoyed the 50% off on the price of the starter kits. So even if you have no interest in the contest, it is a chance to get some cool stuff for half the price. Check out the starter kits and the rules for the contest here.

ZigBee Wireless & Python

I recently became interested in ZigBee Wireless Radios as part of Home Automation and tracking home energy usage. ZigBee is a wireless mesh networking standard intended to be simpler and less expensive than other WPANs, such as Bluetooth. They are very useful in in wireless control and monitoring applications due to the low power-usage which allows longer life with smaller batteries, and the mesh networking provides high reliability and larger range. My first exposure to their usage was a hack to the popular Kill-A-Watt power monitor which adds wireless reporting and is called the Tweet-a-Watt.

After implementing the hack and doing some measurements throughout the house I decided I wanteds to expand the monitoring of my energy usage and started looking for a reasonably priced kit I could have some fun with and learn about my energy usage. After one false start I came upon Digi, which manufactures a line of wireless radios and some cool evaluation kits. I researched three of the kits and decided on the iDigi™ Wi-9P Starter Kit ZB.

My main reason for going with Digi and this kit is the ability to use Python in controlling the reporting of the data. There is plenty of documentation in getting the network up and running, monitoring and modifying the presentation (reporting) and adding sensors to the mix. Python scripts are written and then uploaded to the network using the Embedded Gateway Configuration and Management web page.

My network is up and I have two sensors sending data, one sending temperature and light and the other sending in just temperature. As I make additons to my network, either by adding additional sensors or enhancing the reporting I will include steps and screenshots. Stay tuned as I am just getting started.

Note: I am not affliated with any of the companies mentioned in this blog and all products written about were purchased by me.

Tuesday, July 7, 2009

First Post

This is the first post of my personal blog. I will be writing about my development interests, F/OSS and occasionally politics, but usually in how it relates to technology. I am currently participating in a contest using XBee wireless sensors to demonstrate ways to save energy and will write about that also.

I welcome feedback but expect it to be polite and spam-free.