This is NG for kids. National Geographic is selling to children. Er, I didn’t think they’d stoop that low. Anyway, this represents news, maybe good news. I bumped into Ruth, the doggie wig lady at the bookstore. NG has an article in last month’s issue on the doggie wigs. It turns out a year and 12 more fired employees later, I am still the only person in the world besides Ruth who knows the doggie wig business from the ground up. Keep your eyes open.
I was at the bookstore due to an unsuccessful morning planning session for the robot. I cannot control motors directly with my precious Arduino because it outputs maximum 40mA and the DC motor requires 500mA. Therefore I must build or use a controller. The control system was diabolically complicated and I studied it for 8 full hours. I’ll build it, but for a different reason than it being difficult—the chip gets hot.These motors must be able to go forward and backward. Therefore I tested a controller called an L293D. Even with a computer chip sized cooling fan, the chip gets hot enough to burn your fingers. Certainly hot enough to damage anything it touches, such as my expensive plastic breadboards. But I learned the chip contains an H-bridge, something I can build out of spare parts already in the bin over here.
[Author’s note: the L293D chip is an example of sheer engineering stupidity. Further research shows that the manufacturers are quite aware of the heat problem, but dumped the chip on the market anyway. Other chips that do the same job do not overheat. The fact that it is a known defect with no warning sticker tells you what kind of people you are dealing with in this trade.]
Most pleasant was the discovery of a new generation of well-written Arduino books. Plainly the use of this model has become popular enough in the past year to attract decent authors instead of the eggheads and jerkfaces that came before. If I’d moved faster, I could have been one of the new authors. But, as usual, not being rich was a severe impediment and it does not help that there are so few places to buy electronics in this third world state. Even the common ICs have to be expensively imported from California.
Expect weekly progress again. The said books are incredibly expensive but I have a budget for August to December of $200 for educational printed matter. It will cost all of that easily. I do not recommend any book for beginners as I am only able to understand much of the material after painstaking experimentation and needless failures. But keep at it because after a while I could go back and read the books and see what they meant. But I also see they were sufficiently retarded to screw up the explanation in the first place.
Did I say the motor was complicated? I should show you complicated with what are called shift registers. Remember the experiment I published where I got two LEDs to count down from 30 to 0? Without detracting from that major feat, those LEDs were still not doing much but blinking. They had no memory or knowledge for what numbers were displayed. I could not add or subtract any of the numbers, much less get them to display a reading from a sensor. (A proprioceptive sensor, in case you were wondering.) More about these registers to follow, they are a fascinating contraption.
The motor must be geared. That single realization took hours of research. True, I could have just asked a robotics expert provided one was available, but the investigation covered acres of other information so not a minute was wasted. The electric motor by itself is so weak, you can stop it with your fingers. That means as soon as you set the robot on the floor, the wheels stop. Try using a bigger motor and the robot will crack into the nearest wall before your sensors have time to react.
This led to an Internet search for plastic gears. I was appalled at the costs for these pieces of plastic. Lego dominates the market and they are expensive beyond all reason. They are generally packaged as specialized kits containing parts shaped for one specific construct. Their gear packages appear to contain dozens of the same gear size. What good are twelve gears the same size?
Return Home
++++++++++++++++++++++++++++++++++++++++++++++
