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.

You may remember version 1.3 of my Teensy Breakout Board, and some of the planned improvements I mentioned. Well, it’s a year later, so I should probably get around to actually talking about it.

I finished v1.4 last year, and I even had a bunch of them made via Seeed Studio’s Fusion PCB service, and they turned out great. We’ve been using them for numerous projects, and just recently I finally got around to the protective fix I added in v1.4.

Teensy USB Protector

I modeled this tiny part and 3D printed it. It’s got a hole for a screw, and two slots for zip ties. The photos below show the rest.

Teensy BOB v1.4

Teensy BOB v1.4

Teensy BOB v1.4

Teensy BOB v1.4

Okay then, the chance of the Micro USB connection getting ripped loose from the Teensy has been reduced quite a bit! The zip ties hold the cable end in place to the plastic piece which attaches to the fifth hole on the PCB. I’m looking forward to never have to see another Micro USB jack ripped loose.

Teensy BOB v1.4

Oh, and one more thing… I ran into Jasmine during Maker Faire and we talked about Tindie, and somehow she convinced me to start putting things up there, so now the Teensy BOB v1.4 is available on Tindie in case you want or need one.

The Noisy 85s

I posted just a bit about the ATtinyNoisy boards I had made from OSH Park, but there’s plenty more to tell.

My original plan was to use CR2032 batteries with these, but I found it just didn’t have enough juice to make noise, so I tried using two CR2032 batteries and that didn’t work much better. I ended up grabbing a nearby 9 volt battery to test with, and that worked well, and since I had a bunch of 9 bolt battery connectors, I chose to use those ordered a bunch of new 9 volt batteries from Amazon.

When it came time to program and assemble all the boards, some of them worked, and some didn’t. I wondered if it was because some of the chips I got were from different vendors, including some on eBay that were probably counterfeit. I spent way too much time chasing the wrong problems until I figured it out. (Maybe you’ve already figured it out!)

When I originally tested with a 9 volt battery in the shop, it was an old 9 volt battery that was down around 7 volts. Do you know what the voltage rating for the ATtiny85 is? Well, it’s 2.7 V ~ 5.5 V. Yeah, I was trying to feed it too much voltage!

At this point I had soldered on the battery connectors and was staring at a dozen brand new 9 volt batteries. The board didn’t have room for a LM7805 voltage regulator and I didn’t have time to get new boards made. I ended up taking the 9 volt batteries and shorting them with jumper wires until the voltage dropped to about 7 volts, at which point they worked fine. Yeah, I just wasted lots of electricity to get them working properly. NBD.

Below is an example of what they sounded like.

The idea was to make a bunch of these, and put them in a space, and then interact with the space and experience the sound coming from different directions. You can’t really experience it through a video, as you need to be in the space and move through it to participate in the piece.

The code is dead simple, and just does an analogWrite to a PWM pin on the ATtiny to generate some noise.

// ATtinyNoisy

int piezoPin = 0;
int randomPin = 1;
int randomValLow = 0;
int randomValHigh = 255;
int interValLow = 1;
int interValHigh = 3000;

void setup() {
  pinMode(piezoPin, OUTPUT);
}

void loop() {
  randomSeed(analogRead(randomPin));
  analogWrite(piezoPin, random(randomValLow, randomValHigh));
  delay(random(interValLow, interValHigh));
}

The Noisy 85s

Each ATtinyNoisy unit was placed in a paper bag, and hung from a piece of monofilament fishing line with a binder clip. (I had plenty of binder clips around!)

Here’s a few more photos from the installation that I did at UWM’s Kenilworth facility during SHiN|DiG on Friday, December 16, 2016. With many of my installations (and work in general) I focus on cheap things, often simply presented. I tend to go with the theory that if you can’t make something large, make a lot of little things.

The Noisy 85s

The Noisy 85s

The Noisy 85s

The Noisy 85s

The Noisy 85s

Big thanks to (former) student Maks for helping with the install and uninstall of this piece.

Maks

Maker Faire

I’ve been to a lot of Maker Faires in the past five years, but it’s mainly been in the Midwest (Detroit, Kansas City, Madison, Fort Wayne, and of course, I help produce Maker Faire Milwaukee) though I did make it out to New York a few years ago, and Washington D.C. for the National Maker Faire last year…

But I’ve never been out to Maker Faire Bay Area… until now. Yes, friends, I’ll be out there this time around, and I hope to see you there.

I won’t be wearing my Maker Faire Producer hat though… This time around I’ll be working the booth for Brown Dog Gadgets, who just completed their (successful) Kickstarter Campaign for Crazy Circuits, which is a LEGO Compatible modular electronics platform. Yes, LEGO bricks and microcontrollers mixed together. Fun!

I’ve done a number of projects for Brown Dog Gadgets over the years, and while I didn’t have lot to do with the new Crazy Circuits project, I pitched in where I could with a few ideas and a bunch of code. It’ll be exciting to share the work with a large crowd! (And exhausting, from what I hear. Even though Maker Faire Milwaukee is the largest free Maker Faire in the U.S., the Bay Area crowd still has us beat!)

(I’m not sure if we’ll make it to #BringAHack or other fun events, so if you want to meet in person, look for the Brown Dog Gadgets booth.)

SpringTime4

SpringTime4 was inspired by something my former student Maks showed me, which he called a Victorian Amp. I couldn’t find any good info on it (Oops! I should have looked up Victorian Synthesizer instead) but since I still had a large speaker left over from the Sonic Titan build I decided to build something similar.

SpringTime4

Instead of paper clips (or solder) I used two stretched out springs to complete the circuit. This worked well, because as the speaker coil energized the top spring would bounce up and break the circuit, then fall and complete the circuit again.

SpringTime4

To make things interactive, I added a button that could be pressed to start the device. This allowed people to interact with it, and also added another piece to complete the circuit. The whole thing is powered by a 9 volt battery, which I also left exposed, so people so see what provided power. I didn’t want a full enclosure that would appear to hide things.

SpringTime4

I used alligator clips to connect things, which allowed for disconnecting the button unit from the speaker, which makes it a little easier to transport.

SpringTime4

I took SpringTime4 to the Madison Mini Maker Faire and I really enjoyed watching people interact with it and then asking them if they knew what was happening. Some people sort of figured it out, and for those that didn’t quite get it, I explained how it worked. I think as a maker you tend to forget that even a really simple device can be difficult for people to understand, depending on their familiarity with things like electrical circuits.

SpringTime4

One of my favorite parts was when an 8 year old kid tried to makersplain to me how I should improve it. It’s nice to know that even kids think they’ve got great ideas about how someone else should do things. ;)

SpringTime4

The one improvement I’ll like to see is making it louder (if possible). It’s typical that I test things in my shop and they are fine but when I bring them into public and the environment is noisy, it’s hard to hear things. Since the visual component of seeing the springs move around is a large element of the piece, if I can’t make it louder it’s probably not a huge deal.

Here’s a short video showing SpringTime4 in action. Enjoy!

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