Today is Christmas Eve 2014. What a wonderful time of the year when family and friends have the opportunity to visit, renew friendships, and find out just what happened over the past year. It is also a time of remembering and celebrating when Jesus was born. For those that have put their faith in Him, He has become their Savior. Many biblical historians believe He was born earlier in the year, around the April time frame rather than December. I’m not really hung up on the specific date, but am glad we take the time to understand what He has done for us, especially in the area of giving.
I’m always on the lookout for various DC motors and motor kits. Well, today I had the opportunity to build a brushed DC motor designed and sold by Darcy Whyte from http://inventorartist.com/. He is an amazing person who loves mixing technology with art. Once you hit his site you will see what I mean.
If you are looking for a site that has interesting inventions such as a clock made of a record, a line follower robot, learning about Arduinos, and many more cool projects, this is the site for you.
He calls this kit a Dinky Motor kit that he sells through his store. Here is a link to his instructional video. I followed the video and had my Dinky Motor running in one hour. The great thing about Darcy’s kit is that he has laser cut all the parts and each part fits perfectly. You can use a touch of glue if you want to, but in reality the parts press together so well it is not necessary to glue any of them.
Below are a few pictures and description of the build:
Basic parts of the Dinky Motor kit (notice the rare earth magnets)
(L to R) Frame of the motor, armature parts pressed together
Frame disassembled so the brushes could be added
Frame of the motor with the brushes installed and the completed armature (with commutator)
Added a power supply and a door bell to complete the circuit which made it easier to start and stop the motor.
Once all of the parts were assembled, the rare earth magnets were installed (this can be a little tricky), and batteries were wired up, it was time to press the door bell switch to see the armature start move. I did all of the above and pressed the button, but nothing moved – it just sat there!
I knew it wasn’t the batteries or the door bell button since I just took them off another DC motor I took to my son’s wedding a week ago to show some homeschoolers about DC motors.
So, I checked the orientation of the rare earth magnets. They were installed correctly. Next I looked at the rotor and commutator assembly. All of the varnish had been removed from the commutator. That left the brushes. If you remember from other motors I have written about, the brushes are the most difficult to build for brushed motors (that is why I like to make brushless DC motors, or BLDC for short). Sure enough, I had not removed enough of the varnish off the copper wire on one of the brushes. Once I used the sandpaper on one of the brushes and then carefully pressed the armature assembly in place, the Dinky Motor spun up and ran like a top. You can see the motor running in the 20 second video below.
All in all, a great DC motor kit. You can tell that Darcy has had several versions developed and kept improving it each time. I love the simplicity, the attention to detail, the video instructions, and the homemade appearance of the motor. Once you get your kit, you can plan on about an hour to assemble and troubleshoot the motor. One thing you must keep in mind is that you should plan on about (3) AA batteries to power the motor – just so happened I had an extra battery enclosure that I used. Suggestion: you might want to get one of the battery holders from Radio Shack ($2.99 USD) or make a trip to a local electronics shop. This was an enjoyable build and I trust that you will enjoy it as much as I did. Merry Christmas to all.
Quote for the Day: “I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.” — Albert Einstein
A few weeks ago we were asked to travel to eastern Kentucky and visit and a school that had recently started a STEM program. While there we learned most of the students were able to go to the University of Kentucky (UK) to learn about the nine engineering disciplines that UK offered. Some students were ecstatic about what they learned from the professors and administrators. The second day some of the same UK representatives visited the school to discuss additional careers related to STEM. On the third day we had a session at the school about the various robots my sons and daughter have purchased or built (see below).
Six robots, one brushed motor, and one BLDC shown at eastern KY school
The robots (L to R) shows the first robot we ever built at home – a wastebasket robot that was tethered to a manual control box. This used old TYCO motors installed with a circuit board inside the upside-down wastebasket. It ended up being one of the most popular robots that day.
The robot to the right of the wastebasket robot is called Sparki. It was programmed to avoid walls or other objects. Since it was slow, it did not garner a lot of attention. Someday the students will see how powerful the robot is. It uses an Arduino board as its brain and is very flexible to program.
Next up was a brushed motor; I used it to show the students that motors and/or servos form the basis of the infrastructure of a robot.
As can be seen above, next was an R2D2. This robot was bought pre-assembled and it was the hit of the day. It is completely autonomous and uses voice recognition to hear the command and normally follow through. On this day, R2D2 was quite obstinate – in a good way. We gave it some commands and even used the “Do you remember…?” (Chewbacca, CP3O, Darth Vader, etc.) question to get a response out of R2. Other interesting games we played was “Spin the Droid” and “Play Message.” The students were enthralled.
Next was a Lego Mindstorm NXT 2.0 basic robot. I had installed an app on my smartphone and was able to control it. With the third motor it could really peal out. One of the students wanted to write an app. Things are looking up.
Was able to take a laptop and the software to control the robotic arm. Originally the robot arm was tethered to a control box like the wastebasket robot and you had to control in manually, but a 3rd party company now sells a USB cable that ties to a laptop and you can use the computer to control the robot. This was a little advanced and the software was brand new so it was not as effective as I thought it would be.
The second motor was a brushless DC motor (BLDC) that uses a reed switch instead of a commutator and brush assembly. Explained the reed switch is pretty stable but not many of these are used in industry.
The last robot was a small robot from a company called Robotis. It is from a kit called OLLO and you can build approximately 12 different robots. You can also use their software to program them if you’d like. This robot was a line follower and it was speedy. The students liked how fast it ran around the black line.
Finally, if you look closely at the picture you will see a Rubik’s cube. As mentioned in a previous post I had a video of Mindcuber (another Lego Mindstorm NXT 2.0 robot) so the students could see how quickly it solve the Rubik’s cube shown. They all wanted one.
Close up of most of the robots and motors
Overall, the students were really engaged. STEM is a new part of their curriculum and they are just getting started. After 1-1/2 hours and many questions, it was time to return to central Kentucky. It amazes me each time I do a STEM session to see how advanced these students are. Some really want to get down to the nitty gritty. I imagine if we had the time, we would have been there playing with the robots for another three hours or so.
Quote for the Day: ”The people who get on in this world are the people who get up and look for the circumstances they want and if they can’t find them, make them.” — George Bernard Shaw
Recently, we added a new topic to the website called brushless DC motors also known as BLDC. BLDC motors are used in many applications for several reasons: they are light, have high efficiency, and are quite compact.
One of the neat things you can do is to make different circuits that will turn the electromagnet on and off. This makes for some real innovative designs. Although we have built four BLDC motors from kits from the folks at the Simple Electric Motor company, they also have other kits that you can investigate and build. Once you feel comfortable about building these kits it is time to advance and come up with your own designs.
Here is the link to our new BLDC motor page. Enjoy something new!
Quote for the Day: “It may be that those who do most, dream most.” — Stephen Leavock
In our last post we mentioned there are certain applications that use brushless DC (BLDC) motors. Succinctly, here are a few that you may or may not have thought about:
- Do-it-yourself (DIY) home improvement projects industry,
- Radio-controlled vehicles industry,
- Heating, Ventilation, Air Conditioning (HVAC) industry, and
- Electric car industry.
In DIY home improvement projects, people use power tools that have BLDC motors installed in the tool that makes them lighter and at times more powerful.
Radio-controlled (RC) vehicles such as airplanes, cars, helicopters, ships, and the latest craze, quadcopters, all use BLDC motors because of less maintenance, being compact, and being lighter.
The HVAC industry uses BLDC motors because they are lightweight, compact, have fewer maintenance needs, and are simple to replace.
Finally, there seems to be a need for alternative fuel vehicles these days. This has rejuvenated the electric car industry with new designs that have better reliability. Part of the increase in reliability has to do with BLDC motors. Below is an infographic from a U.S. company called Sinotech. I ran across this company when I was checking out BLDC motors. That is the beauty of the Internet – with Google, Bing, or Yahoo, all you have to do is come up with a search term and you can learn so much about motors, robots, and their place in the world.
Quote for the Day: “The grand essentials of happiness are something to do, something to love, and something to hope for.” — Chalmers
This week I’d like to introduce you to a new type of motor, called a brushless DC motor. Some people shorten brushless DC motor as BLDC motor. After building brushed DC motors for a few years, I yearned for a motor that would not be so hard to assemble the brushes and the commutator. This has been the number one problem when building a brushed DC motor. After searching the web, I found a website called Simple Electric Motors run by Mr. Serge Pozmantir. The website was devoted to Serge’s son, Stan, who won several Texas science awards with his motors and experiments. By now Stan has graduated and probably has a job somewhere.
Anyway, my sons were interested in learning how to build the BLDC motors so I bought a few. Below are two of the many kits you can purchase and build. Recently, Mr. Pozmantir has updated his website and it is much faster with better navigation than what he used to have.
The brushless motor above uses an opto interrupter circuit to make it work. Please note there are NO brushes to deal with. However, you must do some soldering and you have to be careful when you assemble these motors due to a sharp pins being used as part of the shaft. At the bottom of the picture you will see a small rubber grommet that covers the end of the sharp pin. The opto interrupter circuit is shown at the top of the picture. As the motor turns the circuit controls when to allow electricity to energize the electromagnet. This is a pretty fast motor, but not as fast as the one below.
This brushless motor uses a reed switch with a transistor to make it work. It is one of the simplest motors to assemble, is fast, and it works very well at low voltages. The reed switch is shown on the left side of the picture between the motor shaft (with the “S” and “N” permanent magnets) and the upright support. If you look close you can see the reed switch is attached to the support. When the magnet on the shaft gets close to the reed switch, the two pieces of metal inside the glass tube become magnetized and are drawn to each other. At this point current flows through the transistor, the transistor opens, which then permits more current to flow to the electromagnet. As the magnet moves away, the reed switch moves back to its original position and no more current flows through the transistor and none through the electromagnet. Inertia keeps the motor running along with the reed switch and transistor circuit until the next magnet magnetizes the reed switch.
There is another kit that Mr. Pozmantir sells that uses a reed switch with a separate magnet that helps control the speed of the motor. If you want to learn more, hit the link above and check out the kits and experiments. They are put together well and you will enjoy building them.
Sometime in the future I will make videos of some of these BLDC motors and post them on the website, but in the meantime, enjoy these pictures.
Next week we will learn where these special BLDC motors are used.
Quote for the Day: “Make the little decisions with your head and the big ones with your heart. Do that, and you’ll be just fine.” Kevin Roberts, CEO Saatchi & Saatchi, the largest advertising agency in the world
Students these days like things that move. Parents like to see their students be engaged. That’s why when I have the chance to teach about magnets I’ll eventually get around to discuss direct current (DC) motors.
DC motors have some unique qualities that can be used to teach basic principles of electromagnetism. Most students understand how to make an electromagnet using a battery, wire and a nail. It can be difficult to understand the movement of electrons in the wire that are used to create an electromagnetic field (emf). However, it is undeniable that something happens when the electromagnet picks up a paper clip. That simple process demonstrates the attracting qualities of an electromagnet.
In a similar fashion the wire windings around the armature assembly are attracted to and repelled from the fixed magnets. Once this process is understood, the next principle is the idea of a “switch.” In this case, this assembly is called a commutator and it is involved in the process called commutation. The commutator takes care of acting like a switch and is used to help reverse the polarity of the circuit when the electricity flows through it.
In the final analysis, DC motors have three basic principles:
- attraction and repulsion,
- a switch (commutator), and
- reversing the polarity of a circuit.
When the DC motor is wired correctly and these three principles work together, the DC motor will hum merrily along. This is what caused me to be enthralled about building my first DC motor. Finding the materials, following the directions, wiring the fixed magnet, wiring the armature, and adjusting the commutator. This is one of the reasons I feel it is important for those students that have a preference for Science, Technology, Engineering, and Math (STEM) to have experience designing and building DC motors.
Quote for the Day: “Man’s mind, once stretched by a new idea, never regains its original dimensions.” — Oliver Wendell Holmes
Back in November 2013, I wrote a blog that talked about electric motors and skimmed the surface on where those motors were located. So today I plan on walking through the house to count all the motors in each room. It will be very interesting to see how many motors there are in this house. Let’s start in our basement:
- There are several motors in our old VCR
- Couple in the CD player
- Fans in the desktop PC
- Disk drive in the PC has a motor
- Several toys that have motors for vibration
- Bathroom fan has a motor
- The furnace has a squirrel cage motor
- Our sidewall venter has a motor
- A real old cassette player has two motors
- The electric clock has a motor
- Electric saw
- Electric drill
Now to the kitchen:
- The refrigerator has several – one for the compressor and one for the fan inside the refrigerator
- The disposal
- The fan over the stove and microwave
- Can opener
- The juicer
- Oven clock
Let’s check the rest of the first floor:
- Another wall clock
- Answering machine tape player
- Smartphone vibrator motors
- Electric screwdriver
- Vacuum cleaner
- DVD player
- VHS player
- Home entertainment CD player
- Video camera
Time to hit the second floor and see what appliances and other equipment that have motors:
- Vacuum cleaner
- PC with a fan and disk drivers
- Laptop with a fan and a disk drive
- Hair dryer
- Electric razors – one in the boys bathroom and one in the master bathroom
- Electric toothbrush
- Several robots
- Nine DC electric motors that have been built
- Fans for summer
- Aquarium pump
- Canon Powershot camera
- Bathroom fans
Time to hit the attic:
- Furnace blower
Now it is time to hit the garage:
- Electric scroll saw
- Upright electric drill press
- Automobile mini-vacuum cleaner
- Garage door opener
Time to look in the cars:
- Fans for the heaters
- Fans for the radiators
- Windshield wipers
- Starter motors
- Power windows
- CD players
Outside the house:
- Two air conditioning units
Al in all, there are at least 80 electric motors in our home. They are in all sorts of devices – large and small appliances, power equipment, clocks, cars, air conditioning systems and the like. So, how many motors did you find hidden in your apartment or home? Don’t be too surprised if you find a lot more motors than you originally thought. Most everything that moves uses an electric motor. Have fun being a super snooper!
Quote for the Day: “If I have seen farther than others, it is because I was standing on the shoulders of giants.” — Isaac Newton
As mentioned in past posts, I love to build things, especially small direct current (DC) motors. There is a fascination designing the motor, collecting the parts, building the motor, and seeing it work for the first time. It reminds me of a cardboard puzzle where you search for all the pieces, put them together correctly, and when it is completed you have such satisfaction seeing the end result.
So it is with a robot. Robots use various types of motors as well. Some use basic DC motors that are controlled by a small microprocessor (sometimes called an electronic brain) that you program. These motors spin freely and can get to a high revolutions per minute (rpm). Some need a gearbox or variable speed motor controllers to work properly. Other motors used in a robot are called geared motors, ungeared motors, brushless motors, and servo motors. Each can be designed for a specific application.
When I went to college, robotics was not part of our curriculum. We worked with vibration damping, fluid flow, heating ventilation and air conditioning (HVAC), statics, dynamics, machine design, metallurgy, etc. to understand certain principles for design. Today, robotics has expanded to just about all college engineering schools and is a popular course for many students. It is one of the best ways to integrate mechanical engineering, electrical engineering, and computer science into one package.
If your middle school or high school has a robotics class or after school activity like VEX Robotics or Lego Mindstorms or Robotis, I would highly recommend that you give it a try. This website will help you get the basics about DC motors, however, the application of motors and using motors for a worthwhile project is the next step up from learning about motors.
Quote for the day: “Many of life’s failures are people who did not realize how close they were to success when they gave up.” — Thomas A. Edison