Build A Sensorless Brushless DC Motor Controller

October 19, 2013 by Todd Harrison 43 Comments

[Davide Gironi] shows us how to implement a sensorless brushless DC motor controller (sensorless BLDC) using an ATmega8 microcontroller. In order to control a BLDC motor you need to know its rotational sequence position and speed so you can calculate and apply the correct current phase sequence to the motor windings at just the right time.

Simply said, sensorless BLDC means you’re not using a purpose built sensor to determine the motor’s position and speed, however, you are sensing the motor’s sequence position using the back EMF signal coming from one of motor’s coils that is not currently receiving power. When this back EMF signal crosses zero voltage a microcontroller can calculate the rotational speed and when to switch to the next power sequence. This technique is not good for position control motors but is great for continuous motors like computer fans and drives were the slightly reduced wiring costs make this type of BLDC control favored.

If you want to build a BLDC controller we recommend starting with [Davide’s] last project on sensor controlled BLDC motors. You can also checkout these interactive demonstrations for more understanding on the different BLDC configurations.

Follow along after the break to watch the video demonstration of [Davide’s] sensorless BLDC controller controlling a motor from CD-ROM drive.

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Tour Of Chicago Hackerspace: Pumping Station One

October 16, 2013 by Todd Harrison 20 Comments

As you may know I was on vacation in Chicago last week. I got a chance to jump on the blue line train from Chicago’s downtown loop for a short trip out to the Addison stop where I caught a quick bus ride over to one of Chicago’s hackerspaces: Pumping Station One. I was given a tour by some camera-shy members that were there when I popped in. The space had a large welding area with lots of equipment, metal lathes, metal brake and woodworking equipment. You name the shop tool, I think it was there. I even think I spotted a functioning scanning electron microscope! WOW!

The lower workspace was quite extensive. Yes, there’s a second-floor having sewing machines, vinyl cutters, 3-D printers and an entire room dedicated to electronics and robotics. Also, they are in the process of expanding to make the space even larger. If you’re in Chicago I recommend you check them out, it’s an amazing space and an easy commute from downtown.

I hope my iPhone video is good enough to show off their splendid space.
Follow along after the break to learn more and get a glimpse inside Pumping Station One.

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GE Garage And Chicago Ideas Week

October 12, 2013 by Todd Harrison 4 Comments

I’ve been on vacation and managed to get a day to play at the GE Garage mobile fab lab currently setup in downtown Chicago. GE has partnered with Chicago Ideas Week to bring the future of fabrication technologies to a space where the community can walk in off the street and work with some amazing hardware like CNC mills, laser cutters and 3D printers. The group is also giving classes at select times on using the equipment and general electrics. Unfortunately I was in town near the end of this event which will be Oct 20th. If you are in the area I do recommend jumping on the excellent transportation you’ll find in Chicago and have some fun at the space. Here are more details on location, classes and times.

I didn’t expect to squeeze any work into my vacation but I did take a guided tour of the fab space with my iPhone 5s. You can join me after the break to watch the tour, which is a bit rough but still covers a lot of fun topics. Get at look at their line-up or Replicator 2 3D printers. See some fantastic prints from metal made on industrial scale printers. Learn more about the up-scaled CNC seen above that was cutting out skateboard decks. And finish up with an injection molding machine.

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Homebuilt Ultra Wideband Impulse Radar

October 5, 2013 by Todd Harrison 7 Comments

[Dr. Gregory Charvat] tipped us off to a video demonstration of his ultra-wideband impulse radar he built using some of his existing radar gear and a few bits purchased off eBay. The homebuilt radar system worked well in his backyard but not much is covered about the build. [Greg] is promising a new book on practical approaches to developing and using small radar devices titled “Small and Short Range Radar Systems“. He told us that the draft is finished and covers radar systems like doppler, linear FM, synthetic aperture, phase array and also UWB impulse radar. It sounds like an interesting book, which can be pre-ordered on Amazon, and will include schematics and bill of materials so you too could build a UWB impulse radar or other small radar systems. Some of the advantages of a UWB impulse radar system are that it produces sub-nanosecond pulses good for tracking moving objects as well as imaging stationery objects. Such radar technology can even image buried objects like metallic and nonmetallic landmines.

Join us after the break for a little background on [Dr. Gregory Charvat] and to watch his demonstration video.

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DIY Pressure Plate Switch For Your Haunted House

October 2, 2013 by Todd Harrison 17 Comments

Yes, its Halloween time again and the hacks are going to be crawling out of the woodwork for the rest of the month. [Rich Osgood] is off to a good start promising one hack every week until Halloween. Judging from this first project, a DIY pressure plate switch, we think there’s going to be a common theme to follow. [Rich] constructs his pressure plate for almost no cost using cardboard, tinfoil and duct tape. It couldn’t be easier, so make lots of these if your haunting project requires pressure plate triggers to activate any spooks. Judging by the cardboard construction it’s likely they will fail after multiple uses, but you can switch one out quickly requiring only two hookup wires and a bit of tape.

Hopefully we aren’t stealing [Rich’s] thunder by recommending using Xbee wireless remote sensors to covertly monitor guests or trigger spooktacular scares.

We will be keeping an eye out for [Rich’s] follow-up Halloween hacks. Join us after the break to watch the tutorial video on making homemade pressure plates.

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5 Digit Security Code Activated Relay Using Mostly Discrete Circuitry

October 1, 2013 by Todd Harrison 8 Comments

Let’s rollback the hobby electronics calendar a few decades with [myvideoisonutube’s] alarm activation control circuit using a matrix style phone keypad. The circuit is quite old using CMOS 4081 with 4 ‘AND’ gates to hardwire the access code. [myvideoisonutube] references [Ron’s] “Enhanced 5-Digit Alarm Keypad” schematic for this build changing the recommend keypad with a more common matrix style keypad found in touch pad phones. These types of matrix keypads wouldn’t work outright for the input so he cut some traces and added hookup wires to transform it into a keypad with common terminals and separately connected keys. We love seeing such hacked donor hardware even when it requires extensive modifications. [Ron’s] source circuit included a simple enough to build tactical button keypad if you can’t find a suitable donor phone.

Learning how to use mostly discrete components instead of a microcontroller would be the core objective to build this circuit outside of needing a key-code access point or other secure 12 V relay activated device. Such a device would be quite secure requiring a 4 digit “on” code and 5 digits for “off”. You couldn’t just pull off the keypad and hotwire or short something to gain access either. The 4 digit on “feature” does knock the security down quite a lot. However, all keys not in the access code are connected to the same point so you could increase your security by using a pad with more keys.

On [Ron’s] site you will find a detailed construction guide including top and bottom view for placement of all the components on veroboard. Join us after the break to watch [myvideoisonutube] demo his version.

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GuruBrew’s 15 Minute Windows 8 Survival Guide

September 30, 2013 by Todd Harrison 132 Comments

One thing very common to all of us is our reliance on operating systems in our hobby life. If that OS is Windows then you could be in for quite a shakeup with Windows 8. Many readers are Linux or Apple users and couldn’t care less if Microsoft is releasing an entire paradigm shift in desktop navigation. However, you just might find yourself facing this new OS and you’ll look like you’re on training wheels if you don’t get acquainted now, and considering the number of computers being released with Windows 8 its inevitable that day will come soon.

So if you haven’t been behind the wheel of Windows 8 then checkout [Steve’s] Windows 8 Survival Guide from the Guru Brew Tech Show. This is an excellent overview of the new touch screen navigation methods you’ll find in the Windows 8 desktop including hotspots, charms and tiles to name just a few. You’ll also learn tips to get around with a mouse and keyboard. It’s not a complete tutorial on using Windows 8 but you’ll at least know how to navigate, search for apps, work with multiple apps and find tools like task manager, control panel, file explorer as well as your familiar desktop.

Follow the break to watch the short survival guide video.

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