Fun with Electronics and Code

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Category Archives: Electronics

Circuit Board Printer

Kickstarter is a great platform for launching a product without having to have huge infrastructure in place. However it is getting filled more and more with cliché and over-hyped products that are not all that special or have been done multiple time (like the dozen or so 3D PLA / ABS printers from the last year). Still every so often a product will pop up on their that is really interesting / well-built, looks like it will be successful, and is innovative. The Voltara looks to be one of them.

https://www.kickstarter.com/projects/volter/voltera-your-circuit-board-prototyping-machine

This is a Circuit Board printer you set on your desk. It uses Conductive ink, and insulation printable layer(so you can cross traces) and even a solder past dispenser. Everything you need for prototyping your own Circuit board or doing small runs.

Now the biggest “hole” in my opinion is that it does not have a drill so you cannot add any parts that need through hole otherwise you will have to whip out the drill press and do it manually. Not really and issue but for the cost ($1,499) it would be good to have that at lease be an add-on.

Best of luck to the Voltera team.

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Arduino vs Netduino

So I have had a few questions about if the Grand Prix / Pinewood derby track timer design or code would work on a Arduino. Well the short answer is no. Now that does not mean you can’t build a track timer with an arduino (I looked at them when initially consider the design) but there are a few reasons why (in my opinion) the Netduino is better in this situation. The most important is how the interrupt triggering works vs polling that you do on arduino.

If you want to know the “exact” time a car took to travel down a lane the resolution of that time is dependent on how small you can make the loop and that resolution can change if something else occurs on the arduino.

With the Netduino however you can set up hardware level interrupts on each of the input pins and those events have a timestamp from the hardware layer. Now it take considerable longer to process the events in the netduino but since you have that timestamp it is very easy to calculate the time elapsed. This allowed me to get to x.xxxx seconds vs x.xxx to x.xx seconds with the arduino.

Now some may ask if that is necessary and in response I will just give this example. In our first race after building the timer the final race was so close that on video you could not see a difference between the cars. Thier times were 3.1415 vs 3.1417.

If the time resolution was less than x.xxxx then this would have been recorded as a tie. Since using this system we have not had a single tie. This time resolution seems to fit the track we have which is 43′ long and only the first 10 to 12 feet has slope… if your track is shorter than that then you might need a higher time resolution.

Well I hope that helps. let me know if you have any other questions.

Parts and Supplies

Well it has been ages since I posted last but wanted to let any of you that might actually read this that I have found a couple of great places to get parts and supplies. For the last few months I have been running a Robotics club (based on the 3Pi Robot http://www.pololu.com/catalog/product/975)with some other fathers with kids around my sons age. We have done the line following, maze solving and are now moving on to much more advanced stuff like using an Ultrasonic Sensor and IR receiver. lots of fun.

Well one of the other father pointed me to a seller on Ebay called Chip_Partner http://stores.ebay.com/chippartnerstore and it is some Chinese group that sells electrical components dirt cheep and includes free shipping. So we needed 5 ultrasonic sensors and decided to give this place a try. Well for less than 12 dollars we had 5 of them shipped. It was supposed to take 2+weeks to arrive but 4 days later they showed up. Not sure how that works as this shipping would seem to cost more than that parts but it works. We have been using the ultrasonic sensors for a couple of months now with no issues.

The second place is Deals Extreme http://dx.com/. At first it just looks like another fake inline store that will just steal your money and if you ever do get it, it will not be what you wanted. However I realized that they have an entire section devoted to Arduinos and their stuff is super cheap (I mean cheap and not inexpensive). Some of it is clones of designs out there available for free on the web. what got my attention was this board: http://dx.com/p/avrmega328p-pu-development-board-for-arduino-152598 this Arduino has built-in Servo headers and is $16.60 US shipped. If you want to separate out the power for your motors the you can add this board: http://dx.com/p/l293d-motor-driver-expansion-board-motor-control-shield-blue-172881 it is only $8.80 US shipped so for about 25 dollars you can get 3 of the major components you would need to convert a old Remote controlled car into one controlled by an Arduino.

So  I am going to order those 2 board and see if we have the same luck that we had with that Ebay group.

Great Kickstart Project that closes on the 15th of july

Check out this cool kickstart project. It will allow you to test your own Arduino experiment in space using a myriad of sensors.

http://www.kickstarter.com/projects/575960623/ardusat-your-arduino-experiment-in-space?ref=category

New life for the GPRT

Well there is new life for the Grand Prix Race Timer that I build earlier this year. project. Over the last couple of weeks I have been talking with some friends and I came up with a new use for the Netduino controller. It is a quiz machine (think Jeopardy). Not sure yet if it will be a 4 or 8 person device but each participant will have a trigger and then when a question is asked the first person to trigger it will get to answer. I am hoping to use the controller with no hardware changes but just build a different device to plug into it and provide the triggers for the players. Then do an LED at each station that shows which one was clicked first. Next week I’ll be working out the hardware design and then getting the parts, then I’ll do the code changes over Christmas and New Years.

For the trigger I am going to do a short piece of PVC with end caps and then a trigger at the top. Then a LED that will sit on the table in front of them (2 actually, 1 pointing forward and 1 pointing backwards). All of this coming to a collector that would host the 2 Ethernet cables going back to the controller.

If you have any ideas about how to make this better please let me know.

Our HP Touchpad Arrived!

Week ago last Friday we received the HP Touchpad I ordered as part of the employee special in the US. I was going to post a Pic the second it got here but instead decided to wait and post my impressions after working with it for a while. Well after having it more than a week I can say this is one fun yet functional device. I remember looking at an original iPad a while back and not really liking it. Then looking at the androids and liking them but just could not justify the expense (~$300 for a decent one). When I heard the announcement on the HP Touchpad I looked into it but the cost (499$) is what a netbook or economy laptop cost. So when HP started these fire sale on the devices I tried to get one. However, I was working a big project that weekend and didn’t hear about it until long after they sold out.

Hoping that HP would have an employee sale, I started looking into the device more. I found out that the devs over at XDA developers were working on a Android port for the Touchpad and I then  I figured “hey if WebOS doesn’t turn out I can always flash it to Android like I did with my HTC tilt 2 last year”. Well the sale finally came. I was able to sag one and it only took ~36 hours to show up (Good job HP!!!).

For the last week I have been working on it with my wife and the kids, and of course discovering some of the games like Tanked (which allows up to 4 players on the device or I can play again someone on my Pre2!).  Bottom line I have to say I am happy with WebOS and wont be switching to Android. Now I will still load up the dual boot on an SD card to check it out but I don’t think I will be re flashing it. In addition, my wife is starting to like it, so most likely it will become her device.

The thing that converted me was not something you get standard on the device, it is called  Preware. It is a homebrew app store that has a ton of applications, themes, patches and tweaks for WebOS devices (which can brick your phone / touchpad if you’re not careful). With that I was able to patch the functionality on the browser (and other areas) so that it works a lot more like a desktop one (hold click to bring up a context menu and such). Also the browser experience on the WebOS is very fast and in many cases is better than my Vista Laptop or Linux Mint workstation running Firefox and Chrome. I have only found 1 website that would not work on it but it was an obscure one with lots of custom flash. One other thing they have is a patch for the Bluetooth driver that allows your WebOS device to pair with a Lego Mindstorm NXT. Not sure what I will do with that yet but it does sound promising.

Defiantly hoping HP will restart manufacturing and realize that the issues was price point and not feature set. In face the only thing that I have not been able to find was a decent mapping software. The integrated Google or Bing maps on WebOS devices lets you see maps and plan routes but don’t do turn by turn. Nav-It that is available from preware kind of works but is not stable and is hard to use. That is only thing I missed about my old HTC Tilt 2 with Windows Mobile (before I put Android on it) is Bing. That is one of the best mobile apps by far and in my opinion the only think Microsoft got right on pre-Windows Phone 7 devices.

More updates to follow.

Track Timer – Additional Build Details and Source code

Well it has been busy the last few months, but I finally freed up enough time to add the design documents for the Grand Prix Timer to the build page on my Blog and add the source code to a new Codeplex project. With these items you should be able to build your own after doing a little homework.

Note: All the design documents I have created are now uploaded. However if you have any questions please let me know and I will add details where needed.

New project

Work has been quite busy since moving to a new team in march but with summer in full swing I have been look at what to do for my next project. Well my kids have been interested in electronics along with some others from our home schooling group. Also I have received a lot of questions about how the electronic eyes work in the Grand Prix Finish line worked. So with that I am going to start doing a series on simple set of circuits that will demonstrate basic electronic principles and work up to Integrated Circuits.If you have any in particular you would like to see me do please drop me a line.

This is cool!!

The embedded controller I used for the Track Timer, the Netduino, has added my project to the project page on their website. check it out: http://www.netduino.com/projects/

Testing the Track and Timer together – SUCCESS!!

What a great weekend!!!

Saturday we (Danny, My kids and I) setup the Track and the timer together for the first time. It was also the first time the entire track had been assembled. We had to drill the holes for the light sensors and the second support board and then everything fit right together. By 11:30am or so we have everything ready to start our first tests.  The first issues we ran into was that lane 4 would not register that it was receiving  light. After taking the finish line apart and checking alignment  we discovered that the whole in the track was about 1mm off and the IR LED holder in the top of the frame was 2 mm off in the other direction. So a combination of the to displacements (although each was in tolerance) meant that the light was not getting from the IR LED to the Photo Transistor. We reassembled everything and by 2pm we start the track tests.

The Track is not sealed yet (as we might need to make some fixes if track issues were found), so we raced 8 cars that Danny brought with him that did not have recent lubrication and therefore should not drip / drop anything on the track. The first run was a mess (the cars had not been used in a year) and half of them jumped the track. We disregarded this run and the following 8 runs whet very well.  Below are the Stats:

Track Average: 3.5040
Best Time 3.2417
Worst Time 4.1188
Maximum Deviation: 0.8771
Standard Deviation: 0.2159

With this testing complete this means the Timer and Track are ready for racing. This week Danny will be clear coating the track this week and I will make some final tweaks to my code. The race day is March 19th and now I will be focusing on helping my kids with their cars and hopefully get time to work on mine. I meant to take more pictures during testing but it was so busy, I forgot to pull out my camera until near then end when we had already started breaking down the track. I will make sure to take pictures and video during the setup and while racing on the 19th.

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