Arduino Ultrasonic Anemometer Part 6: Mechanical design

If you’ve read through my previous posts of this series you know that here is an Arduino and two home-made PCBs together with 4 transducers waiting to work together as an ultrasonic wind meter. If you haven’t you may click here for an overview of posts on my anemometer project: https://soldernerd.wordpress.com/arduino-ultrasonic-anemometer/

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Milling the base plate.

For this wind meter to work, the four transducers need to be held in place somehow. Even during testing and development I wanted some reliable mechanical setup so that I don’t need to worry about it all the time. For this prototype I don’t need anything waterproof that I can put outside for a prolonged period of time. Anyway it will be sitting on my bench most of the time so wood works just fine for me.

Here two videos of the CNC milling machine at work:

The transducers are 16mm in diameter. 16mm plastic pipes are readily available from hardware stores. They are intended for electrical wiring so you also get matching angles and the like. So I got myself 8 90-degree angles and a 2m pipe from a local hardware store. I think I’ve mentioned before that I want the transducers to sit in a 20cm distance so make the wind meter rather compact.

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More CNC milling.

I’ve just recently attended a CNC machining course at the Zurich Fab Lab (http://zurich.fablab.ch/) so I decided to do my first CNC milling project and use my newly aquired knowledge to make a wooden base to hold the plastic tubes (and PCBs) in place.

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Mounting the PCBs. Still using my Arduino Mega here.

I’ve used some left over 18mm melamine-coated multiplex. It’s extremely sturdy and has a nice smooth surface. I ran my first tests with a Arduino Mega so that’s what you see above but I’ve replaced that with a Uno by now. So all the software development will take place on an Arduino Uno and its Atmega328.

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My prototype sitting on the bench

Besides the two boards you already know, there is a 2×16 characters LCD. I thought it would be nice to have a display connected to the Arduino when writing the software. Just to see what you’re doing. An easy way to drop some debugging output and of course display the measurements once we are ready to actually run this thing.

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View from above

There is a little PCB attached to the LCD display. It mainly holds a trimmer to adjust the contrast as well as a resistor for the backlight LED. Since I had to make a board anyway I also included a 10uF plus 100nF ceramic capacitor as well as a protection diode.

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Lots of wires to connect everything

As you can see from the photos above, there are definitely more and longer wires than necessary. But for a prototype I’m always reluctant to soldering things and cutting wires to their minimal or optimal length. I like to be able to just unplug a board and do some changes to it.

When I started writing my software I didn’t have a clue which signal will be on which pin. I just plugged them in as I went along. And I changed it several times until I was finally happy with it. So I do need some flexibility. But it also makes the setup a bit of a mess I must admit.

Ok, the hardware is working now. Time to write some software and see if we get it all up and running. See you next time.

Click here: http://soldernerd.com/2014/11/21/arduino-ultrasonic-anemometer-part-7-basic-software/

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