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My boss is sorta into R/C cars and remote control vehicles in general. I brought my R/C car up here at least 2 years ago but it was in a state of disrepair and I hadn’t really done anything with it until just now. I started tinkering with it a couple of weeks ago, when I decided I really needed to do something with it or to get rid of it (and that was out of the question).

The biggest problem with it was the speed control. It used to be fairly hard (or just fairly expensive) to control the speed of a motor over a couple of amps. The stock option in the 80’s/early 90’s was very simple: just connect a resistor inline with the motor to lower the voltage that the motor receives. This is a horrible solution for 2 reasons. One, you are sinking all of the energy not used by the motor into heat. This is not efficient. Two, it’s not affordable to get a variable resistor to handle more than a couple of amps. So the stock solution was to use a whole additional servo to switch between maybe 2 different resistors to give you 3 speeds. This adds extra weight and complexity into the system.

Enter the late 90’s — high power MOSFETS go into mass production enough to be affordable. Electronic motor speed controls enter the hobby scene in full force. The electronic speed control generates a pulsed signal based on how much power you want to apply to the motor. Think of it as a square wave. With the throttle at 10%, a wave is constructed that spends 10% of its time in the ‘high’ position. The rest of the time it is low, or zero volts. If this cycle is repeated slowly, the motor would actually pulse forward very slowly. However, if you were to up the frequency of the wave so it is maybe hitting that ‘high’ mark a couple thousand times a second, you get something very useful. The signal is still only high 10% of the time, but it’s being switched on and off so fast it acts as a constant voltage to the motor. The motor actually responds like it is receiving a lower input voltage. Given an R/C scenario with a source of 7.2 volts and 10% throttle, the motor acts like it is receiving .1*7.2 volts = .72 volts. So the motor spins slowly. As I push the throttle open more and more, the ‘duty-cycle’ of this very high frequency wave becomes higher and higher (20%, 30%, 40%) until it is up to 100%, or full speed.

Now you know how ESC’s work. This post didn’t cover everything I wanted to discuss with my car and used a lot more words than I expected. Look forward to another R/C car post in the near future. At least you (hopefully) learned something. Danno out.

Well, I think this means the official start of snowmobile season. The weather has been colder here and it has seriously been raining for the last 3 weeks or so. More significant yet, my motorcycle is in winter storage. We have 11 foot ceilings in this place, so ever since I moved in I had thought about building a nice high loft. A couple of weekends ago I finally did and man it is nice to have the additional space. It’s nicer yet to have a loft that I don’t need to worry about hitting my head on. The lowest point of the main horizontal section is about 6.5 feet up. Even so, bad memories from the (much lower) 416 loft hang in my head. I find myself ducking and getting up slowly whenever I am under the shadow of the loft.

Like I said, we have had a lot of rain in the area the last 3+ weeks. This has been accompanied by fairly warm weather — we hit 80 last Sunday. On October 12 last year we had almost 3 feet of snow on the ground. At least the low tonight is down below 40. Even so, we’re supposed to have sunny and 60 come this weekend. I’ll probably use the warm weather to change the serpentine belt in my car (that thing has been making a lot of noise lately) and to pull the engine on my snowmobile so I can work on that. Here’s to hoping the colder weather and the snow is on its way soon. I think I hear the heat kicking on…

Happy MTU homecoming to you all! This weekend we had our homecoming games in most of the sports Tech participates in. I’m not so much a fan of the sports, but there are all kinds of hobo-themed events and activities that I enjoy. Most of them are rather crazy, there’s a baked bean eating contest, a 5 legged sac race, a shopping cart race, etc. My favorite of them all is the cardboard boat race. We participated as a hall when the even was first added in 2005, but we were all too busy last year to make a boat. It’s fun to go out there and watch teams of 8+ people sink in the water.

This year it was decided for sure we’d make a boat, so all this summer I was collecting cardboard for it. We put it together over 2 days (we really should’ve started earlier) and it was quite a feat of engineering and craftsmanship given our small time window. We overcame quite a few problems actually getting the thing out of our apartment and managed to weaken the boat quite a lot in the process. I did sail in it this year, and the much weakened boat floated us out on the portage and back again. We had a good time building and rowing in the boat.

My Grandma and Grandpa were also up visiting this weekend. We went out to the Lake of the Clouds in the Porcupine Mountains state park. It was a lot of fun, and the view from on top was amazing. I wish I had taken a camera. This post seems to ramble on quite a bit, but I wanted to get something up and I’m too tired to fix it. Have yourself a happy Columbus day.