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Open Source Hardware

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For all the hobbyist, maker community, DIY'ers, students and beyond - we're supplying free reference designs that you can work with, take from and build up to make your own designs!    No need to start from scratch!

Linear Technology DC1194A Demo Circuit = 200ma DC/DC Micro Module

Click Here to download now! 

                lt1.PNG    lt2.PNG


Demonstration circuit DC1194A features the LTM®8020, a 200mA DC/DC step-down μModule® regulator. The board is preset to deliver a 3.3V output at up to 200mA load current from an input voltage of up to 36V. The output voltage may be modified by simply changing one resistor.

This PADS reference design data set has 19 files including:

    • Schematic design in xDX Designer format (.prj)
    • Layout design in PADS 9.5 format (.pcb)
    • Bill of Materials for the design ( Bill of Materials.html)
    • PDF of the schematic design ( (Schematic).pdf)
    • PDF of the layout design ( (Layout).pdf)
    • Property definitions file (netlist.prp)
    • PCB Configuration file (pads95.cfg)
    • Land Patterns
    • Schematic symbols


Be sure to check out all 24 Reference Designs found here: http://www.pads.com/reference-designs/?cmpid=9050 can be used with our new inexpensive (PADS based) Designer Schematic and Designer Layout tools now available for the hobbyist/maker community from Digikey !http://www.digikey.com/product-highlights/us/en/mentor-graphics-designer-software/4171?cmpid=9050 as well as our desktop PADS products.

Cheers !    John

Front panels can cost a lot. As an alternative I had a theory that I put to the test this week, and it worked out well. The theory was that for home-built projects, surely trophy/jewellery type engraving could be used for labels.


It turns out that it can be done on enclosures in most high streets/malls as a same-day service - just using the engraving services of a key cutting or jewellers store : )

In the UK, the chain 'Timpson' was used here, on this aluminium enclosurethis aluminium enclosure (these Hammond aluminium enclosures are really great - simple, with a nice finish):




It was very efficient. I just told them the text I wanted and where, just written on a piece of paper along with a quick 30-second pencil sketch.

They figured out how to center it, the font size, etc., based on their experience with their tools.

I think they did an awesome job!! I'll be going back to Timpson for future projects.

I had a wake up call using Eagle Cad and a third party libraries. And I wanted to share how my ignorance caused my boards to fail (for now).

Just for reference the board uses an Atmega328P SMD and i wanted a smaller and cheaper part than a normal crystal. So I went with a resonator, there are a few very cheap and very small. I am not that good on creating parts layout by myself so I searched on the libraries at hand for a resonator with the footprint similar to the one I wanted to use. And very quickly I found a smd resonator on Sparkfun-FreqCtrl library and the part is RESONATOR-SMD. First I was very happy to actually found this part. So I put the part on my PCB and send it to fab for manufacturing. The board came back beautiful red (I had to pay a little more for color selection). Then I notice that around the resonator there were some solder mask missing, but said to myself this must be a size limitation from that cheap Chinese fab. I am like a little kid whenever I get mail, so I ran to get my iron and started soldering. "No need to do any measurement, I am 99.9% sure the design is correct" I said. If fail then I will test, but I wanted to solder right away. So I did.

Latter after the boards start failing I then went back and did some measurement, just to find some missing solder mask and some exposed copper. The copper exposed then again I thought at first it was because of Chinese fab, but turn to be my mistake not the fab.

Lets see the picture bellow, look the black region is missing red solder mask. And at the borders you can see exposed copper (blue arrows). The missing solder mask (black part) does not causes any problem. However the exposed copper do. It causes my resonator to short to ground making my board fail.



And what was the cause of all? The actual part on the library had instructions to be constructed exactly as it was done. There is a layer in eagle called tStop. The tStop layer is the one that allows solder areas of copper to be exposed. This layer stops solder mask in a specific area. This part has a rectangle over the entire part. The size of this rectangle plus a small isolation in the board causes this tStop rectangle to go over my ground plane, and causes the copper to be exposed. On the image bellow, the big white hatched rectangle is the tStop that caused the problem. This made my twenty boards order to fail.



I have three options:

1. Etch (manually)  out that exposed copper to a distance that I can solder the part

2  Cover with heat resistant tape the exposed copper

3. Paint it over with solder mask (that I do not have at hand).

I am going to get a few pieces of tape, and try to cover the exposed copper in order for me to use these boards. But anyhow I edited my design and send a few more to be made, this project need to be finished and quickly. In about two weeks I should be getting them back and hope this issue is water under the bridge.


Hardware design has its ups and down, but it is well worth it. You win some and loose some and learn a lot during the process.

I should try to contact SparkFun about the part, or submit a pull request with the fix. I am a noob, this might be the right design and I am the one mistaken. Anyhow for PCB with a big ground plane close to this part this is not working. My guess is that the rectangle is intended to avoid ground plane under the part and not to stop the solder mask. This must be a layer mistake.


For the new PCB I did a ground plane cutoff polygon around the resonator, removed the tStop from the part and made the side contacts a little bigger (for easier soldering). When I get the PCB back from fab will post again with the new board. Hope that it work.


This PCB eagle files are not posted now, because this board is for a surprise event. After the event all will be posted. If you want to know, the board is just a usbaspLoader using an Atmega328P with an Arduino header footprint. Nothing revolutionary. Oh and of course, instead of a crystal with two capacitors it is using a 16Mhz resonator.

If you do not know what the ESP8266 is... oh boy. It is a cheap WIFI Uart module (google it).

I have been playing around with the ESP8266 for a few days now. While doing my testing I realized that most of the time my problems are faulty wiring. Yeah I know, noob right. Well what can I say, I am a noob. Anyhow it is frustrating trying to debug software problems while still having hardware issues.

This week while reading on the web found a service that can manufacture a PCB for $5 per square inch for 3 boards and it is made in the US. I am not in continental US but close enough. Also it says the part will be sent back in 12 days (more or less). The service is not important, the important is that my mind ran very quickly.

Would I be able to do a 1x1 inch pcb to interface my ESP8266 delicate 3.3V signals to my strong 5V Arduino ?..... CHALLENGE ACCEPTED!

After a few Eagle Cad iterations (about 3 or 4 in 2/3 days) I came up with a simple board that is suppose to be able to do that. BUYA! It shall be called "WifIco".


Ok all this sounds very quickly and it's because it has been. I didn't even mounted a breadboard prototype before ordering. This one goes all or nothing. For a while I have been wanted to do a pcb using smd components and this sounded like a good chance for it. And very important keeping the design on the $5 mark (there is not that much money to spare here you know).


Board Features

  • Power input of 5V
  • RX and TX signals 5V friendly
  • 3.3V regulated output
  • Breadboard friendly pin out
  • Space at the bottom for a mini usb port in case the device is firmware programmed and need a power input from a cell phone charger or something. Wanted a micro usb but I think I have salvaged a mini usb port someplace around
  • GPIO0 and GPIO2 exposed (not 5V friendly, be careful)
  • Connector to plug in the ESP8266 directly to the board.



On the bottom side there are two resistors that should be solder shut to pull RST and CHPD to high. They are just put there in case I needed to use the board for firmware upgrade or needed them. From the schematic capacitor values do not mean nothing. Should check on 3.3V regulator circuit guide lines for actual values. If input voltage is clean you may skip them ( but don't tell anybody I said that).


This is how WifIco will looks like (at least from the images from the OSHPark web site):


Top Side


Bottom side


My eagle design files are here. All is on Public Domain licensing if anybody wonder. I do not need mention nor credit for nothing you do with this.


This may or may not work, in a few weeks I will know! If you don't ever build it or at least try it you'll never now.



I received an email from the manufacturing service that says, the board was sent to factory on Nov 10 and should be back from factory on Nov 20. After that I guess mailed back to me (+5 more days). My guess is that in best case scenario I will be posting on results back somewhere during December (I hope). Still I am exited about the success of this project and hope you are too.


Update 2 (Nov20):

I received a new email that says, board was received from factory and was shipped to me. This occurred on nov 19, 2014. Today is the 20th. Normally this things take anything from 2 days to 7 days to get here. As soon as I have it with me, the plan is to do a continuity test on the contacts and solder the parts for full testing.


Update 3 (December)

The board were shipped to me and received. I did my best soldering the components to the board. I made big errors on the silk screen. But important connections seems to be ok.

I soldered the components to the board as best as I could. and this how it looks like.




I am sending signals from an Arduino to the ESP8266 board and it seems to be receiving them ok. However it is not consistent when receiving communication from the ESP8266 back to the Arduino. My guess is faulty soldering on one of the transistors, but have not tested.


My Errors (for now):

1. Error in silk screen ( Vin is Vout, GND is not ground, TX is RX... )

2. Solder pads should be bigger to allow hand soldering correctly. Specially on Tantalum capacitors, they cover the entire pad so soldering is pain.


There is the issue that I should have tested the design before ordering the pcb but that is part of the adventure. It is a risk I had to take and do not recommend but do not regret.


Possible fixes I would do to this.

1. Fix Silk Sreen

2. Bigger solder pads

3. Change bottom usb connector to be micro usb.

3. Add a mounting hole if space available.

4. Do similar board for the ESP8266-03 board.

5. Add level shifting to digital IOs to make them 5v tolerant also.

6. Add smd switch in the bottom for firmware update mode.


There is so much to do with the board without actually making it bigger. I love adding features but is hard to do in so limited space.


A physical bitcoin made by Casascious. I suppose as an attempt to make it easier to use? That coin could be have been worth anywhere between $300 - 1200 USD this past year! (via Casascius)

While bitcoins aren’t backed by a government body or well-known bank, the digital currency is still gaining ground in some communities, who will not let the concept die without a fight.


One community that’s taking a huge risk on the concept is the Massachusetts Institute of Technology. Next fall, MIT will give each student $100 worth of bitcoins to see how the digital currency fairs in a real-world setting. It only makes sense that MIT would sponsor such a project – after all, it does have a Bitcoin Club.


MIT Bitcoin Club President Dan Elitzer and colleague Jeremy Rubin organized the experiment, which includes raising half a million dollars from alumni and other donors to make the project possible. Any leftover money will go to the university to continue to enhance programs for undergraduate and potentially graduate students.


Elitzer hopes the experiment makes MIT the biggest bitcoin-based community on the planet. If the project is a success, it could send the value of bitcoins through the roof, as the value fluctuates based on demand, much like stocks. If you were thinking about getting in on the investment, now would be the time.


But what about security? While there hasn’t been specific word on just how secure use of the currency will be on campus, MIT computer scientists and faculty are working hard on preventing digital hacks, as the currency is not insured and when stolen the owner is simply out of luck.


The students hope that this project is the first step towards making bitcoins a widely-accepted form of currency and compare the concept to the early stages of the internet (let the kids dream), but they aren’t the only ones predicting a bright future for the electronic form of payment. A plethora of bitcoin-based gadgets are also under development, like MEVU’s wearable bitcoin bracelet.


While bitcoins would really have to catch on in order for the product to sell, MEVU created a Bluetooth-powered bracelet that enables users to pay for their purchases with bitcoins by a simple flick of the wrist.



The silicon bracelet is a prototype and some adjustments must be made before it ever reaches stores. For one thing, it’s based on the iOS, but most Apple apps are no longer supporting bitcoins. What is more,, most retail locations are not yet accepting bitcoins, making purchasing the bracelet to shake your band at your computer a hard sell. Nonetheless, it shows forward thinking and a lot of confidence in the technology overall.


Have you invested in bitcoins? It may be time to make the jump.



See more news at:


I want to share with you some nice developing story: We are developing a open source platform for 3D printing and CNC - the T-Bone.


First of all it is just an 5-Axis stopper motor motion controller for the BeagleBone. But if you digg a bit deeper into the details I think it is quite awesome. By relying on othe open source implementations for this topic we were able to integrate all the best solutions in a fraction of time to develop everything ourselves:

- The motion planning is adapted from the awesome TinyG software, the 3D printing adaption from the Marlin firmware

- The web Interface for the 3D Printer is using the excellent Octoprint GUI

- The schematic integrated the open source Arduino Leonardo as realtime MCU

- We borrowed ideas and solutions from the RAMPS board and the Replicape


By reusing everything that was the same as other CNC and 3D printing boards we could focus on implementing novel features. First of all we created a very special architecture which reduced the real time requirements for the beagle bone massively so that we can implement all 3D printing and CNC features easily in Python. Second we can use all features of the great Trinamic chips we have used. This enables for example homing without having mechanical end switches wired – magically by detecting the motor load while carefully touching the mechanical frame!


And giving back this solution as Open Source (CC-BY-SA for the hardware and AGPL v3 for the software) gives the warm fuzzy feeling of contributing some really cool solution …


Currently we are trying to find enough funding for our first production run on indiegogo. So if you like this project support us by buying a board, t-shirt or sticker.


I hope you like this project. What do you think? Is such a high level programming approach something you could use in your work and projects??

bitcoin logo.JPG

(via bitcoin.org)

Speaking of open source, the Bitcoin cryptocurrency source code is open. Hence, all the crazy digital currencies that have come out.


Bitcoins have received a fair share of criticism, but it seems most critiques of the electronic currency are a thing of the past. The digital currency is gaining widespread acceptance, including the installation of bitcoin ATMs at various locations throughout the world, the ability to pay in bitcoins at casinos in Las Vegas and even the ability to pay for tuition in the virtual coin. Goodbye paper dollars, hello bitcoins.


Robocoin recently created its very first Bitcoin ATM and competitors are following suit. Genesis 1 announced the creation of its bitcoin ATM, which it will feature at the 2014 ATM Industry Association U.S. Conference February 11-13 at the Loews Royal Pacific Resort at Universal Studios in Orlando, Florida. Bitcoin ATM manufacturer Lamassu has also joined the trend. It sold its 100th bitcoin ATM in December and has 120 order already placed for 2014.


The enthusiasm has crossed into Las Vegas, where this week two casinos announced they will be the first in the industry to accept bitcoins as currency. Both The D and Golden Gate hotels, along with select gift shops and restaurants on-site, reported they will accept the electronic currency as cash. Each cashier station at the establishments will be equipped with the electronic payment service BitPay to make the transaction seamless.


While it may not be a surprise that bitcoin ATMS are popping up everywhere, most probably wouldn’t assume that universities would accept the virtual coin as cash, until now. A private university in Cyprus led the charge and now the United Kingdom announced its first university to accept bitcoins. Students at the University of Cumbria can currently pay for up to two classes in bitcoins, what the university calls an experiment.


While there are still concerns about the security of bitcoins compared to physical currency, it certainly seems the virtual coin is catching on. Will bitcoins replace physical currency? Only time will tell.



See more news at:


EDN has a great post on the Open Hardware Summit 2013:


Open-source hardware in the creative world

Open Hardware Summit attendees packed the Kresge Auditorium at MIT last Friday with eyes and minds wide open to hear from engineers and makers on their open-source designs and overall thinking on the concept of sharing ideas and knowledge.


EDN spent the day at the Open Source Hardware Association-run event and shares a few of its finds here. Some of the following designs may at first strike one as quirky one-off successes but broader thinking shows extensive opportunities beyond these examples.

I'm glad the article highlights my favorite device from the Summit:

If you want to go far fast, go open hardware


When Ryan Fobel wanted to automate biomedical engineering research at the Wheeler Lab at the University of Toronto, he realized he would have to build his own system. He enlisted the help of his brother Christian, who has a PhD in computer science, to build the Dropbot.


Dropbot is an open-source digital microfluidics (DMF) platform built around an Arduino-based instrument and controlled by Microdrop, a custom software interface.





I had the plesure of attending the Make: Hardware Innovation Workshop last week prior to Maker Farie.


Here's my gallery:



And my YouTube playlist of videos I shot during the Innovation Showcase:



I particulary liked this PCB mill called OtherFab:





I recently started working the BeagleBoneBeagleBone, an Open Source Hardware Single Board Computer (SBC).  For those not familiar:

BeagleBone is a low-cost credit-card-sized Linux computer that connects with the Internet and runs software such as Android 4.0 and Ubuntu. With plenty of I/O and processing power for real-time analysis provided by the TI Sitara™ AM335x ARM® Cortex™-A8 processor, BeagleBone can be complemented with cape plug-in boards which augment BeagleBone’s functionality.

source: BeagleBone Quick Start Guide


The BeagleBone 101 slideshow does a good job of introducing the BeagleBoard, the BeagleBone and BoneScript.  I've been impressed by how easy BoneScript makes it to control physical hardware with JavaScript.  I am going to walk through some basic BoneScript examples, but first I'll describe the experience of connecting the BeagleBone to my computer for the first time.


The Bone does come with a preloaded microSD card with Angstrom (the default Linux distro for the Bone).  However, I wanted to make sure I had the latest software, so I downloaded the latest Angstrom image and flashed it onto the microSD card.  The BeagleBone Quick Start Guide has more info on how to do that.


Next, I connected the BeagleBone to the USB port on my laptop (running Ubuntu Linux 12.04).  This provides power to the Bone which then boots up off the microSD card.  The BeagleBone initially shows up as a USB mass storage device:


The contents include drivers for Windows users to continue with the next step.  Luckily, no additional drivers are needed for Linux:


Upon ejecting the BeagleBone USB mass storage device, the BeagleBone will then appear as Ethernet-over-USB interface:

afustini@lappy486:~$ ifconfig eth1

eth1      Link encap:Ethernet  HWaddr d4:94:a1:92:59:57 

          inet addr:  Bcast:  Mask:

          inet6 addr: fe80::d694:a1ff:fe92:5957/64 Scope:Link


          RX packets:233 errors:0 dropped:0 overruns:0 frame:0

          TX packets:252 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:35937 (35.9 KB)  TX bytes:66085 (66.0 KB)

The kernel messages on my laptop:

Feb  8 00:52:15 lappy486 kernel: [211558.726102] cdc_ether 2-1.2.2:1.0: eth1: register 'cdc_ether' at usb-0000:00:1d.0-1.2.2, CDC Ethernet Device, d4:94:a1:92:59:57

Feb  8 00:52:15 lappy486 kernel: [211558.760561] ADDRCONF(NETDEV_UP): eth1: link is not ready

Feb  8 00:52:15 lappy486 kernel: [211558.760784] ADDRCONF(NETDEV_UP): eth1: link is not ready

Feb  8 00:52:16 lappy486 kernel: [211558.786409] ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready

Feb  8 00:52:16 lappy486 kernel: [211558.787311] martian source from, on dev eth1

Feb  8 00:52:18 lappy486 kernel: [211560.786518] martian source from, on dev eth1

Feb  8 00:52:18 lappy486 kernel: [211560.792507] martian source from, on dev eth1

This allowed me to then ssh into the BeagleBone:

afustini@lappy486:~$ ssh root@

root@'s password:

root@beaglebone:~# uname -a

Linux beaglebone 3.2.34 #1 Wed Nov 21 14:17:11 CET 2012 armv7l GNU/Linux

root@beaglebone:~# cat /etc/issue


|       |                  .-.           o o       

|   |   |-----.-----.-----.| |   .----..-----.-----.

|       |     | __  |  ---'| '--.|  .-'|     |     |

|   |   |  |  |     |---  ||  --'|  |  |  '  | | | |

'---'---'--'--'--.  |-----''----''--'  '-----'-'-'-'

                -'  |



The Angstrom Distribution \n \l


Angstrom v2012.05 - Kernel \r


root@beaglebone:~# ls



Here's a screenshot:


The BeagleBone also presents it's self as a USB serial device, too.  A terminal emulator (I use gtkterm on Linux) can then connect to the BeagleBone's console.


In my next post, I'll show the slick built-in web-based IDE, Cloud9, and how Javascript can be used to control circuits connected to the BeagleBone using the BoneScript library.




eagle.jpgThe line between 'Technology Tinkerer' and 'Early-Stage Startup' is faded and gray.  Both are driven by passion, both are tight on cash, and both are run by people with a clear view of the bigger picture looking for tools that can easily get the job done.  It's no wonder that the toolsets enjoyed by one would be incorporated by the other.


CadSoft EAGLE is a prime example of a tool that works perfectly for startups.  First, the capabilities of the tool are expansive, and far beyond what a casual user would ever need.  There's a schematic editor, layout editor with an integrated Gerber Tool, and autorouter, which are all straightforward and simple to use.  It also runs on Windows, Linux, and Mac, which for some reason isn't as common as one might think in CAD programs.


As can be strangely glamorized, many early startups' initial funding comes from a conversation with the husband/wife.  This can lead to a less-than-impressive expense account for someone trying to explore an idea.  EAGLE comes to the rescue with a free license for hobbyists that limits the PCB to two layers, 100x80mm, and 1 schematic sheet.  Thanks to the gray area between a hobbyist and someone trying to start a company, it would be easy to rationalize the first couple prototypes as hobby projects and then look to the commercial licenses when it's time to get serious about making money.  Buying the license is also cheap and simple – with the commercial license of the free version costing $69, and the 'fully loaded' version (with autorouter) priced at $1640.  Even better, everything can be bought online in minutes instead of having to call a supplier.


Once a user starts working in EAGLE, more time saving features become quickly apparent.  No CAD program is 'easy' to learn, but the simple layout and menu structure of EAGLE makes getting off the ground quick, if not painless.  When the inevitable problem does crop up, the user base is known for fostering a remarkable support community on the forums. These discussions are visited often by EAGLE experts and Cadsoft staff, making for many excellent responses.  Another hassle for startups trying to get a quick board out is creating schematic symbols and footprints in EAGLE from scratch.  Element14 has a library of EAGLE parts ready for download, saving a ton of time for a new user.  For parts that are not already created, learning to make them is easy thanks to Sparkfun's step-by-step tutorial.  Once the company buys any license, there is free tech support offered by phone which can be handy when in a crunch trying to meet a board house's submission deadline.


A final EAGLE feature that startups love has nothing to do with CADsoft. Where to get the boards made? OSHpark is a board house that makes prototype boards for pretty cheap (but take a couple weeks).  The real benefit of EAGLE and OSHpark is that users can upload the layout file directly to OSHpark's website and be done.  This takes the normal PCB-purchasing requirements of gerber files, fab drawings, and compatibility issues out of the PCB ordering process, making orders almost as easy as hitting 'print'.


From start to finish, EAGLE has some real perks that startups will notice.  Easy to get going, easy to buy, and easy to have boards made.  Because that's what it's all about: getting things done in the fastest, cheapest, and easiest way possible.


It is about time that Windows Phone 7 is used for a DIY project. The overall dominance of Android and iOS in DIY projects was stifling.


In a mission to use natural resources more efficiently, Engineer Mike Linnen of Morehead Technologies, has taken several Microsoft (MS) devices and services and turned it into a surprisingly useful DIY automated and controllable sprinkler system. A Netduino Plus controller is at the center of the system, controlling the sprinkler heads. The board uses MS .Net Micro Framework and an onboard Ethernet port. The board sits and waits for HTTP requests and monitors the manual pushbutton.


Using a Samsung Focus (Windows Phone 7 handset), the user can send commands through to the Netduino via MS cloud based service Azure. The concept is, Azure keeps the internet connection open to make remote procedure calls to the Netduino board. Linnen's idea was to give access to the board without "punch holes" in his internet router. In other words, access the Netduino behind a firewall.


A schedule is made for the sprinkler system to follow, or by a remote command from the Samsung Focus. Additionally, and the most amazing feature, the system monitors weather conditions. If the day is expected to get rain (over 39% chance) the sprinklers will not be turned on.


This is just a only summary of the fine work Mike Linnen has accomplished. Read more at Linnen's project's page.


I see the usage far outreaching just a sprinkler system. Anything that can be scheduled or triggered remotely could use this tech. I look forward to reading more about MS products and DIY. Perhaps this project will get added to the Microsoft .Net Gadgeteer site.







The RP-2ADP is an adaptor for infield wiring of the DB9 Serial connector.

Allow easy access to the TX, RX, and Ground pins.

The RTS and DTR pins (Pins 4 and 7) are also available for CAN bus or port powered devices.


* Available in male or female configuration.

* Tab for wire strain relief.

* Mounting Hardware included.

* Accepts 24 - 16 awg size wire.

* Push button Spring-Cage Terminal block make easy secure wire connections.


Available at Phoenix Engineering.


Jane Gordon and some of the robot cast


Only two options: subject yourself to the insane logic of robotic whims or step off the mortal coil.

Based on the play Hedda Gabler by Henrik Ibsen (1890), and written by modern playwrite Elizabeth Meriwether, portrays the heroin Jane Gordon as a depressed, pregnant, housewife dreaming of escape in Side Show Theatre's production, Heddatron, presented on the stage of Steppenwolf's Garage Theatre. Heddatron opens showing mundane settings: a living room, kitchen, dining room. A projected video of an interview setting a tone of mystery, possible impeding disastrous events, with the seriousness of a congressional hearing. From there we follow the stories of four different sets of actors. Victorian period settings bring us insight into Henrik Ibsen's world: why he created the play, his rivalry with other characters. Jane Gordon's odyssey into loathing, madness, and robots. Jane's family-- in their sometimes violent, anti-robot --search for Jane herself. The video interview concerning the overall event. Although this sounds grave, the play is a comedy. It has many truly funny moments, and every actor is likable  The play has a sound track that make the play feel like a film. It has a few moments that will extract shock and applause from any audience. And of course, robot cast members that are unparalleled in any quality and function in any play to date. Heddatron is a must-see for any engineer.

So, where did Side Show Theatre  go for robot actors?-- Chibots, Chicago's Robot Group of 15 years. Only one person could pull it off: Eddy Wright of Wrighthobbies.net. The Wrighthobbies' "BahBot" microcontroller development board were used extensively in Heddatron's robot actors. I was able to speak with Eddy Wright about the development of the Bahbot controller, the play, and robots. The following is excerpts from our conversation.


Did you design the robots? Are they based on anything you have ever done before?


[Side Show Theatre] showed me some sketches, and they were a lot larger than anything I've worked on before. The "Hans" bot is 6 foot 5, and top heavy. Handling this was a big challenge. It took us over a month to just design Hans properly. We lowered the center of gravity, and it worked out well.


Did you build them all single handedly?


At first we had a big team, about 8-10 people on the job. But there is just so much room inside the bots for hands. So, it didn't make much sense to have 8 people on a bot simultaneously. We whittled the team as we got closer and closer to the opening date. It ended up being just me and Stuart Hecht [Chibot member] in the end finishing the up, with a diverse enough skill set to handle both hardware and software. We took parts from the other designers and added them in to the final design.


Bahbot controller


Did you design the Bahbot controller from the ground up?


I did it in collaboration with a gentleman named Glen Aduikas, based on one of my original development boards. [Glen] had taken my board and put a daughter board on it for an Xbee. Then another for an SD card, and then more. He sent me a picture saying 'look what I've done to your board.' I was blow away!


Were they off the shelf modules or custom?


He actually custom made little hand-made components for the Xbee headers. They're not custom headers. They're not .1 inch they're .05. And then the SD card slots are surface mount, so he soldered that up.  He showed it to me and said, 'we've love to have a board that could do all this stuff.' I thought that was a cool idea, but didn't think it could fit on a small board. He and I talked back and forth and before too long we were designing it with the same footprint as the original board. We ultimately got it to be the exact same size. 55mm by 65mm. We got it all packed in. They are actually stackable, or psudo-stackable, even though they have tons more packed in.


In the beginning of the performance, several people come out with various custom looking joystick control boards. Do these also contain your Bahbot controller?


The dual joystick are based on the Bahbot controller with XBee radios for the serial communication. All of the bots contain at least two Bahbot controllers.


Was everything running off of your proprietary hardware?


From the controller side to the base, yes, there's one on each side. They are talking xBee to xBee with each other. We chose to not have the base controller controlling the entire robot. We put another [Bahbot] in the robot that talks via serial connection to the original. All the information is passed from one to the next. The firsts takes the information and moves the bot accordingly and passes the information into the next Bahbot. In the case of the Billy-bot, he had some Propeller boards in it. Stuart Hecht, the other guy from Chibots I was working with, likes Propeller microcontroller.

There were a few other Atmel microcontrollers handing single jobs like a string of lights, LED flashlights, glowing objects.


How was the propeller used?


They work good for all the different things going on at the same time [in the Billy-bot]. There was a lot of animation in the head, neck, and the servo controller. So the multi-core capabilities in the propeller worked out well in this case.

The Bahbot has so many different functions onboard, it almost acts like a multitasking processor, like the propeller. I'm a big fan of Atmel AVR microcontrollers, so I settle in on that one as a standard. With microcontrollers at a dollar a piece, it's easy to just drop one in and tell it to do something until I tell it to stop.


That is a lot of onboard tech. The bots moved around silently, and really smooth, what were they moving on?


We used Paralax Wheelchair motors, with integrated numatic 8" wheels. Silent, powerful, and we could control them pretty well. And they don't drain the battery that much either.


Controlled by a Bahbot?


Yea, the Bahbot controls a Pololu TreX motor controller using serial         communications.


Who wrote all the software for communication and control?


That was me.

Once I got rolling on it, I would say it took me 25 to 50 man-hours to write the software. When I was finished with the core, I went back in and put in all kinds of fail safes. You don't want to have a robot going off on its own, or not stopping when you tell it to do. In early testing, we had a lot of drifting. Where the bot wouldn't stop for about 30 seconds. I fixed that.

The serial protocol does a CRC16, with a unique identifier on each packet, if a packet comes in without the identifier it knows it's an error. All the fail-safes are just to stop the robot.


Only 50 hours, amazing. Any communication problems, interference?


We did notice that the xBee uses 2.4Ghz range, and on one of the opening nights we didn't tell everyone to turn off their phones. I didn't think phones would be an issue. But smartphones aren't just phones. They have a wifi radio in them. With a 100 people in the audience, with I guess 75% of them have smartphones, we had some interference. After that, we tell everyone to turn off their phones. We haven't had any issues since.


Is the sounds controlled by your Bahbot controllers?


The sound is piped in externally. It was too hard to time the sounds and electronics properly. In fact each bot in controlled by two people. One for sound and another for everything else.


What about power for the bots?


The bots run off of off the shelf 12V SLA 7A/h onboard batteries and chargers. Some of the bots are able to give two performances on a single         charge but Brack [TV BOT] has a PC monitor and DVD player. He has to         recharge after every performance.


So you built the hardware, and wrote the software. That is an impressive feat. Did you go to school for robotics?


No, my degree is in software development in the early 80s. You know Fortran, Pascal.


So all the electronic design and robotics is self taught?


Yea, I've been working with robotics for 11 or 12 year. That's when I hooked up with Chibots. And have been learning ever since. Being self taught I've learned what I want to learn, what I need to learn. I found none of the controllers did what I wanted them to do. People liked the designs I can up with, and I started a company. And it had grew into what WrightHobbies is today.


Has it been fun?


It's been a great time. Opportunities like this don't come along that often. To get a chance to work on something like this, at this scale, which really challenges all our skills we have within Chibots. To ultimately produce something like Heddatron and have our share of that responsibility and accomplishment, is amazing. Audience members have been quite impressed, that these are real robots.


Thank you for your time. And the play was amazing. I may go again, to be honest.


Thanks. Please do. It was a pleasure talking with you.

Heddatron is playing until April 24th, 2011. Find tickets and info at the Sideshow Theater website.


The Bahbot controller can be found at Eddy Wright's website, Wrighthobbies.net. Please note the Bahbot's wireless programming feature.

Features of the Bahbot controller:

  • ATMega1284P-20      MCU
    • 128K Programmable Flash
    • 4K EEProm
    • 16K RAM
    • 2 8-bit and 2 16-bit Timers
    • 6 PWM Channels
    • 8 ADC Channels
    • 18.432 MHz
    • Dual hardware UARTs
  • On-board      microSD card slot
  • Wireless programming
  • xBee      headers for wireless serial communications
  • All      ports brought out to 2x5 headers with power and ground
  • Standard      size, compatible with PB10 and PB20 prototyping boards and mounts to      Tamiya construction plates
  • Optional      battery monitoring circuitry, selectable power for secondary headers
  • LDO      5v regulator rated at 1A (500mA without heat sink)
  • Preloaded      Bascom Boot Loader



65mm X 55mm, Mounting Holes - 60mm X 50mm

Input Voltage

6.5V to 16V

Output Voltage:

5V up to 1A, 3.3V up to 250mA

microSD Slot:

up to 2GB, standard SD (HDSD in development)

xBee Headers:

Digi xBee and xBee PRO RF modules supported


Standard 2x3 ISP header or Serial Boot Loader


Any Atmel AVR compatible compiler - Bascom & gcc





-Cabe Atwell


DIY Speaker Fabric

Posted by Eavesdropper Mar 1, 2011

paper speaker.JPGpaper s.JPG

Creating a simple speaker on fabric and other materials was demonstrated by Hannah Perner-Wilson in this video. In the best version shown in her experiments, she places wide traces of conductive tape on canvas, and places the material over a rare-earth magnet.


Normal speakers operate by sending a signal through a "voice coil," that is suspended inside a permanent magnet. Force is exerted from the stable magnet to the free moving coil. And the signal through the coil changes it loves back and forth rapidly causing the air around it to pressurize. The pressurized air molecules propagate as a wave, and this is sound.


Speakers are quite inefficient, only able to convert 0.5 to 2% of the power into acoustic power. To make this simple The Power out is equal to the power in multiplied by efficiency.

Pout = hPin (h is efficiency)



So, with enough power, can my future speaker jacket bring the party?



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