Fun with Electronics and Code

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Category Archives: Circuit

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.

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.

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.

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.

Completed and tested – Ready for Testing on Saturday!

Friday:

Well it has been a long road, but I finally completed the build.  I had some delays in getting the mechanical assembly completed but thanks to Bob at HP I was able to get the last few parts I needed machined and the assembly completed.  I started with cleaning all the parts with denatured alcohol and then marking the center lines of each lane on the frame. Then using some steel wool, removed the oxide coating on the back of the “L” brackets, the top plate, and the inside of the C Channel. The H bracket on the bottom is only friction fitted in the channel but I did clean it with denatured alcohol. I then used hot glue to attach the Photo Transistors to the “H” mounting brackets on the bottom and for the IR LEDs on the “L” brackets on top. NOTE: I am told that the oxide coating on Aluminum will reform after about 40 minutes at room temperature, so I suggest gluing soon after cleaning.

Next, I used a section of track that Danny Rose (the track builder) gave me to test out the software and the finish line. It worked great! I was testing with a small stick and whipping it across the lanes to see if then could be triggered by small points (some people like to have pointed tips on their cars) those worked as well but it did not trigger as hard as when the width of the hole was blocked. it can’t be avoided with this design but at least it is close (much closer that any of the races will be). I then tested with the stick whipping it across as fast as I could. I was able to get the lanes to trigger within 0.0007 seconds of each other but never a tie. We will see if we get one on race day but I would be suppressed if we did.

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Shipping cost how much?

I received the 2 aluminum parts I ordered last week and discovered that the shipping was almost more then the parts. It was 27.46 for the parts and shipping was 24.68 for 13lbs and 2 separate shipping containers. What I didn’t realize is that if you get stock that is different lengths (6′ and 8′ as I did) then they have separate shipping containers. Wish that they had told me before hand. Oh well guess I know better for next time.

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