Call me cooped up with nothing to do. That translates into a good study session. Take a look at this object. It’s meaning to me is the first time I ever glanced at a circuit board and knew in a flash what it was for and how it was made. A year ago I would have just trusted whatever was on the package. Want to step through the thought process with me?
Okay, there are six duplicate circuits on this board. Starting on the lower left, there are a series on input jacks next to six green LEDs, each with a transistor and a flyback diode in the next row. Down the middle of the board see twelve more resistors, six of which must each control a base of one of the six switching transistors. Behind those, see six more clear LEDs also with six current-limiting transistors, then to the right edge the little blue boxes which are six relays. At the back top center are six more diodes, possibly Zeners, and a smoothing capacitor. Why, this is a six-relay module sitting on top of an Arduino board. And the Arduino controls the activity of those relays in a programmed microcontroller sequence. The light green connectors are power inputs and outputs, as devices connected to this board require more power than the Arduino can provide. A very useful circuit for robots, and one I think I could build if I had to. Happy Xmas morning, indeed.
[Author's note 2015-12-25: it is amusing to read back down my own learning curve. I now know these add-on boards are called "shields", where in more familiar computerese, I used to call them "daughterboards". It took nearly a year after my first Arduino to get to the stage of building anything like you see here. But I'll match that to the thousands of Arduino owners who gave up along the way. Robotics is not a canyon you can cross in two jumps.
I read for a year before I could do anything useful, only to find out my definition of useful does not follow the regular pattern of getting the Arduino to duplicate some ordinary process. That describes about 99% of everything that is out there. Nothing original in electronics in 40 years. Hmmm, to think, that is about the amount of time ago I tried to learn this stuff and was told not to.
What, the purple thing in the picture? I also knit. I can only knit straight things, like scarves. I don't do it very often, but at least I can knit if I have to. Can't everybody?]
Later, around noon, I completed building a clock timer circuit. That’s the tiny circuit at extreme left of the photo with the black adjustment shaft. Then I connected it to my ring counters, as shown here. This was a fascinating experience, both the build and the sensitivity of the apparatus when complete. By holding my hand near the timer, I could set things into hysteresis (random flashing caused by static). What’s that, you say? Oh, the wool on the knitting needle? That’s nothing, I needed something to keep me occupied while I’m thinking. It is not a stocking.
Even later, I caroused the Internet electronics shops and finally found Pololu. No, it’s not the Hawaiian state flower, but yet another parts outfit in Irvine, CA. They have a unique selection and I have one of their stepper motor drivers, a device that can turn robot steering adjustable to 800 steps per circle. Very fine control indeed. The challenge is the gears; nobody seems to have perfected an adjustable set of gears. That means when you buy the gears, you have to design around the mounting.A partial solution may be parts from Tamiya, a plastic model company. They have chassis and running gears that remind me of Meccano. Here’s another company I never heard of while searching specifically for robot parts. This shows how imperfectly the Internet searches perform for all but the most simple of cases. Months later I finally hear of them because I glanced at a wrapper from another shipment before I threw it away.
So there you have it. Xmas 2011.
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