Andrew Morris had a problem with a small rotary tool built in China. The tool fit nicely in the hand and was useful for precision cutting, drilling, and polishing. Yet for delicate work, the tool was in bad need of a speed regulator.
Andrew had developed an analog motor speed regulator back in the mid-1990s, but this time, he wanted the benefits of a digital regulator. The digital version was just as efficient, but it was less expensive to build and easier to assemble. The digital circuit also provided more torque.
Andrew Morris' microcontroller-based DC motor speed regulator brings control for delicate work.
What a cool looking kit, mrdon - that looks like a lot of fun. Thanks for the link, it makes me want to start playing with my PIC stuff again. Another thing I love about using Microchip products is the technical support that is available, their extensive documentation of their PICs, and their forum community. I have gotten some excellent help when I was stumped on a project that I was contracted to do and wound up making a great friend and partnering on the project with him that (speaking of patents) was eventually patented by the company we wrote the code for.
Yes, it measures the back EMF after momentarily disconnecting the motor. This scheme would not work with a universal motor. You need to use IR compensation for that kind of motor. The analog version of this gadget, referenced in the article, uses IR compensation. A scaled-up version of that circuit would work fine with a universal motor, like the Dremel Moto-tool.
Also, why do you need to have extremely high speed for working on hearing aids. A Dremel moto-tool runs extremely fast without boosting the voltage. I'm afraid to do delicate work at high speed. Do you know something I don't? High speed would melt plastic parts.
Sorry to hear that armorris - that has not been my experience. I am not saying you did this, but what I did find is that there is little patience on the forum for questions that are just thrown out there without evidence of the person trying to solve the problem themselves first. I did notice that when I went into detail as to what I had already tried and where I was stuck with code examples - plenty of folks jumped in with some great suggestions. There are also different areas that help localize where you should post to get the best chance of receiving knowledgeable help. You might want to give it another try - or maybe jump on it to help someone else out ;)
Thanks, Nancy. I'll take your advice next time I need help. When I needed help, I didn't actually ask for it. I tried to find the answer from comments that were already posted, but the archive is just so huge, and I do not know how to sort through them in any useful way.
I saw plenty of people willing to give advice for a fee.
For a fee???? Times have changed...but I am willing to bet there are still plenty of folks who love what they are doing and love sharing their knowledge with others. I needed some help with my last project and had four different people offering very intelligent suggestions that helped me resolve the issue I was having - and they never asked for compensation.
Andy, the small changes you describe to get around patents doesn't seem to work in the world of smartphones. There is a great number of patent suits in that world. Some of the suits are quite successful at banning companies from selling their products in a number of countries.
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