posts tagged with the keyword ‘ppprs’

2017.05.29

PCB

Hey, it’s only been six months since my last post about motor controllers and the Power Racing Series so I guess it’s time for an update! If you missed it, I’m working on a tiny electric vehicle that can serve as a reference for teams of beginners to build their own.

Controller

In the last post I talked about a cheap motor controller that required an expensive throttle and alluded to a method of using a cheaper throttle… here is that method.

I started by asking questions on the Power Racing Series Google Group, and people much smarter than myself offered advice, and that’s where I learned about digital potentiometers. I ended up testing my idea with help from this tutorial and eventually got an MCP4131-104E/P-ND digital potentiometer (for less than $1.00) and paired it with an Arduino Nano that was less than $2.50 to create a converter that allows a cheap throttle to be used with a cheap controller.

If at any point you feel like saying “Hey dummy! You should have done it this way!” feel free to leave a comment. Most of my crazy pursuits involve me learning a lot along the way, and this is no exception, so I’ll keep going.

Controller

After I had a working prototype on a protoboard I decided to design a PCB because I’ve been working on getting better at PCB design for the last two years now, and it’s sort of fun (and challenging!) This is the most complex board I’ve worked on so far, and of course, mistake were made…

First of all, see those wires coming off the board? There should be screw terminals there, but I was unaware that the holes were the wrong size and the pins of the screw terminals did not fit. Argh… wires will do for now.

Controller

Everything wired up and ready to go! Except, it didn’t go… Seems I managed to not quite route everything the right way. Back to the drawing, and tracing all the connections with a meter, and I discovered a connection that shouldn’t be there…

Controller

…but that’s what Dremels are for! I was able to cut the trace and get it working. Back to the computer to make a few changes to the PCB. (And yes, I am still using Fritzing. I’ve gotten used to it, and know how it works, so… okay then.)

Controller

A few weeks later I got a new version from our friends at OSH Park and this one fixed the issues and worked! I should still get similar screw terminals but hey, it does what it should do, so that’s something.

You might notice some of the analog pins and some ground connections broken out at the front edge of the board. There are for future enhancements. It would be fairly easy to add in “cruise control” (for parades) or a speed limiter, perhaps with a keyed switch, to allow kids to drive the vehicle safely. (Again, people smarter than me.)

Controller

Whomp! Here’s my “breadboard” showing everything. Batteries to power the motor, and a buck converter to drop the voltage to 12v for the Arduino and a cooling fan. The throttle connected to the converter and then to the motor controller to control things. We’ve also got a DPDT (double-pole, double-throw) switch in there to allow for forward and reverse to the vehicle, and a kill switch, fuse, and voltage meter. Basically all this will need to be jammed into the vehicle to control it. (Don’t worry, we’ll be using larger batteries, thicker wire, and a larger motor.)

Controller

Here’s the controller with a cooling fan mounted to it. I’ll provide files to laser cut or 3D print the mounting pieces, or templates to cut by hand, which is totally doable. (I learned the hard way last year that if not properly cooled the capacitors on these controllers can blow.)

Controller

I also added a bright blue LED to the board (you can choose another color) to indicate when it’s receiving power. Another suggestion I got from someone. I’m sure there is still room for improvement (like, you know, diodes) but hey, it works and I look forward to testing it.

2016.11.13

Stair Car

I’m going to be posting a bunch about a 2017 build for the Power Racing Series, and along the way I’ll be highlighting some parts of the build and explaining things. We’ll start with the motor controller, because being able to control the speed of a motor is crucial to building an electric vehicle. (Yes, we’re building an electric vehicle. Check out powerracingseries.org for more on this whole thing.)

DC Motor

Disclaimer: In some parts I’m going to keep things fairly simple.

Let’s start with some basics. A DC (direct current) motor spins when connected to power. In the diagram above we’re using a small motor and a 9 volt battery. Connect them together and the motor starts to spin. If you flip the wires (as in red wire to yellow wire, and black wire to green wire) the motor will spin in the opposite direction. This is how “brushed” DC motors work. There are also “brushless” motors, but we won’t get into those.

I sometimes like to refer to DC motors as “Don’t Care” motors. Want it to go the opposite direction? Flip the wires. Want it to go a bit slower? Give it a lower voltage. (Again, we’re simplifying things.)

Motor Controller

Here’s a motor controller. It has a connectors so you can connect a battery and a motor. You can’t make the motor go in reverse with this controller, but that’s okay for now. You can control the speed of the motor, but we don’t do it by lowering the voltage we do it by using “pulse width modulation”, commonly referred to as PWM. PWM is a method of controlling motors, lights, and other things by turning on and off the power really quickly. (Here’s a SparkFun article about PWM.) If you’re wondering why we don’t just lower the voltage (perhaps by raising the resistance) to make the motor go slower, read Why is PWM used to control DC motor speed instead of using a variable resistance?

Motor Controller

OK, so this motor controller comes with a potentiometer. When you spin the potentiometer is varies the resistance from 0 to 100K ohms. This get translated by the controller and feeds the appropriate PWM signal to make the motor go somewhere between not moving at all and full speed. The 100K pot also has two extra wires which work as a simple switch to turn the motor controller on and off.

Before we move on, a bit more about this controller. It’s from China, and it’s really cheap. I only recently discovered it’s a “Leadrise” controller after someone provided this Amazon link. You can find these on eBay for under $13. (Damn, that’s cheap!) I’m going to focus on doing a low-cost build, so keep that in mind along the way.

Throttle

The 100K pot is a nice way to test the controller and make your motor spin fast and slow, but you aren’t going to want a little potentiometer on your electric vehicle! Let’s find a throttle. Now, motor controllers of this variety typically require a “0-5V” throttle, or a “0-5K throttle”. The good news is, the 0-5V throttles are really cheap, the bad news is, this controller requires a 0-5K throttle, which are not cheap.

Magura makes a nice 0-5K throttle. You can find them for around $50 or so. There’s also a 0-5K thumb throttle that’s a bit cheaper. Any of these 0-5K throttles will work fine with this controller, and if you can decipher which wires are which you can cut off the 100K pot and wire in the 0-5K throttle. Easy, right!?

In a future post we’ll get into connecting up the throttle, and after that we’ll look at adding in reverse, and eventually get into building our own throttle controller that will allow us to use very cheap 0-5V throttles with this controller.

See Also: Controlling the Controller Cheaply

2015.10.05

Power Racing Series - Detroit 2015

This is no time to relax! It’s time to see the photos from The Power Racing Series event at Maker Faire Detroit, which happened back in July, that I’m posting in October. Better late than not at all!

Want more? You can see the whole album on Flickr, and scroll down for a video!

Power Racing Series - Detroit 2015

Power Racing Series - Detroit 2015

Power Racing Series - Detroit 2015

Power Racing Series - Detroit 2015

Power Racing Series - Detroit 2015

Power Racing Series - Detroit 2015

Oh, there’s also a video, because Jim finally got around to editing my footage. I shot the DSLR stuff from the ground, and others got the aerial stuff. I also managed about a half dozen GoPro cameras during the event.

2015.07.19

Moxie Board

Hello Racing Fans! I thought it might be appropriate to show you the cars that raced at Maker Faire Kansas City for the 2015 Power Racing Series

Mutt Cutts

Mutt Cutts was one of the cute cars. You may know it from the “Dumb And Dumber” films. Well, here’s a tiny replica. It wasn’t the fastest, but it was the furriest. This was one of those cars that we worried would tip over in every turn. It didn’t.

Sweet Tooth

Sweet Tooth, built by Collin Royster, a prop-maker in Kentucky, was a damn impressive build. The clown head and forks were for decoration only, and got removed for the races.

Phantom 48

Phantom 48 returned once again! These guys just keep refining their already fast and reliable car. The rat rod impressed us with its looks in 2013 and hasn’t changed much cosmetically, but from what I understand they’re constantly tweaking the code running on their controller.

Cartastrophe Jeep

The Cartastrophe Jeep also returned in 2015, and just like Phantom 48, their car looks about the same, and performs about the same. Fast and reliable, most of the time, except when it breaks.

KITT

KITT from OMG is the car from Knightrider, and it did good, not too fast, and not too much breaking down. A good mid-fielder.

Huminator

The Humninator, the only in the series with a full suspension system! The Humninator is a take on The Terminator theme, and a Hummer. A pretty fast car, though it suffered a bad failure in KC, Scott is fixing it up for Detroit!

Herbie

Herbie (The Love Bug) is just adorable, and is the work of Chris Lee (from Nashville’s Kessel Runners Racing) super-star Wars Nerd and prop-builder.

Minecart (Steve)

The Minecart (also known as “Steve” was a big wooden box that surprised us all with its speed and agility. There’s some great reasons to build your car as a big wooden box. An unexpected surprise with this one!

Dangermouse Mark III

The second car from the Cartastrophe was the Mark III from Danger Mouse. I am unfamiliar with the series, but the car is a wedge of cheese. It did well for the first showing.

Jurassic Rover

Jurassic Rover is another really nice build from our friends from the south. I can’t remember which state they were from, but the car was beautifully done.

Duct Tape & Zip Ties

Duct Tape & Zip Ties car is an old classic, build mostly from old bikes. It’s not fast, but it is (somewhat) reliable and goes for the “slow and steady wins the race” idea.

FUBAR Truck

FUBAR brought their old green truck all the way from New Jersey! Bill and his team keep fixing it and breaking it and racing it and having a good time. That’s what it’s all about!

LEGO Car

LEGO Car (as we called it) was built by a team of high school kids. The body was foam and kept breaking, there was a Razor scooter underneath for steering, they used 6 motors, of which between 1 and 3 worked, they blew their controller and used a relay, and they were known as a “rolling chicane” but they had fun and were a crowd favorite. Awesome.

Bigger photos? See them on Flickr. More will be added over time…

2014.08.06

lotusrear2

In June we hit up Kansas City, but everyone knows that July means Maker Faire Detroit, and the craziest Power Racing Series event of the year, pulling teams from the Midwest and East Coast (and even NIMBY from the West Coast joined us this time!)

It was definitely crazy, with eighteen cars we ended up splitting one of the races into two heats, one for “fast” cars and one for “slower” cars. (And hey, Audrey drove Lotusaurus Wrecks to victory for Milwaukee Makerspace in the slow race!)

Once again I did a lot of filming during the event, and this time had three GoPro cameras in place. Here’s the official #PPPRS video:

But wait! There’s more! There’s a YouTube playlist titled Power Racing Series – Detroit 2014 with nearly 40 videos of the action. I’ve still got a lot of uploading to do, including more Moxie skits, but it should keep you busy for a while.

As usual, there’s so much going on at Maker Faire, it’s hard to see it all. While in town we also got to visit OmniCorpDetroit and i3Detroit, both awesome makerspaces in the Motor City.

There are still a few more races this season, including Fort Wayne, Indiana, New York City, and even something in Milwaukee, Wisconsin! I’ll be at that last one, as it’s five miles from my house, though I’m not sure about the other two… If anyone wants to sponsor me to attend a Maker Faire, let me know!

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