Tony posted his reply to “What’s on Your Breadboard” over the weekend. He says that it is an AVR-based LED scanner: “I started out using my standard jumpers but then went crazy with the too-long version.”
Every maker that dabbles in electronics has a breadboard or two (or three, or fourteen) with current and prior projects on them. In the spirit of sharing with our community, we asked on the email list a simple question: “What’s on your breadboard?”
Over the next few days, we’re going to feature some of the replies here on the blog.
First up is Workshop 88 member Karl who shared a photo of his breadboard with an array of LEDs on it. His project is developing a countdown timer with a visual representation given by the LEDs. He pointed out the button which never seems to stay on the breadboard.
Thanks for sharing, Karl!
What’s on your breadboard?
Jim updated his post to his own blog to include some measurements of the effect of breaking the magnet to get the wire wrapped on to it.
He used a simple RL circuit to measure the inductance of the toroid. Very neat to see some values to compare the glued vs. unbroken magnets.
Inspired by Kirk and the Kobayashi Maru, when Jim was faced with the near-impossible task of winding hundreds of turns of wire through a toroid core, he cheated.
By cleanly breaking the core in half and gluing one half to a spindle chucked in an electric drill, the winding became fairly easy. Super gluing the halves together afterward produced a magnetically and physically sound toroid again.
Several folks at the space helped Jim with his experiment, holding wire, counting turns, operating the drill, and of course taking pictures. Many thanks to Ti Leggett for his efforts and skills as the photographer. There are more details in Jim’s project notes, but here’s the video:
New members John and his son came to Workshop 88 yesterday for the Arduino 101 class. Before class they started printing a model of the Sears Tower that they had designed on their own in Sketchup.
The scale of the model is such that each floor is 1 mm tall. Pretty cool!
Inkscape converted a bitmap of the logo to a .svg, the gcodetools extension generated g-code, and vi did the final modifications. The .svg needs a little cleanup, but it was more than adequate for this first test.
We now have a profile that’s calibrated to within a few percent for X, Y, and Z, though there’s still work on max speeds and accelerations. This plot was made with a ballpoint pen in a very crude holder. The bitmap-to-path converter generated inside and outside paths for the lines, so the mismatch of the actual plotted paths gives us some insight into opportunities for mechanical improvement of the shapeoko/penholder system. While the penholder is responsible for some of the tracking errors, we still have a lot to do to tighten up the shapeoko. The plate joining the Y and Z axes wobbles surprisingly. But it’s starting to work!
Update 10/2/12: Using the very convenient test facilities of the axis setup in linuxcnc’s stepconf tool, I maximized travel speed on all 3 axes. The shapeoko1 profile is getting pretty usable. Here’s a little real time clip of it plotting. This one used a Sharpie, and even though it only stayed in one spot while the Z axis raised or lowered the pen, the paper bled the ink into very noticeable dots every time it stopped.
I picked up an OBi100 adapter for the space a few weeks ago, and have been hunting around for a phone that we can use with it.
I stopped by the local Goodwill on my way in to the workshop one morning, and picked up two phones for $1.99 each. One was a Lucent speakerphone that was missing a power adapter (I managed to dig a compatible one out of our giant box of wall warts in the electronics room). The other was a fantastic old GE Model 500 rotary dial phone. One of our members with a bit of experience in the area pegged the year of manufacture as 1965, with the last service in 1984. I cleaned it up with some rubbing alcohol, and we swapped the old phone number placard for a W88 circuit board mask:
It took about 10 minutes of googling to find the pinout on the 4-prong adapter so we could hook it up, and it was hooked up to our Google Voice phone number and ringing.
The alligator clips aren’t a great solution, so I started designing a box to plug it into. I used OpenSCAD to do the design. The source files are available in my GitHub repo, but here’s a couple quick screenshots of the render:
I measured for the holes on the top using a pair of digital calipers, and then did some quick trig to figure out the offsets from the center point of the box.
The pins on the plug are arranged in a trapezoidal fashion so you can’t insert the plug backwards. The bottom of the box is set up so that I can drop in a Radio Shack perfboard with a standard phone line connected to a couple of spring contacts on the wider pair of the two holes. The standoff holes in the perfboard line up with the blocks in the corner of the box, and I have a second 3D model for the bottom of the box that sits below the perfboard.
The most difficult part of designing the box was getting the Workshop 88 logo to come out right. I found this great tutorial on how to use InkScape to build 3D shapes in OpenSCAD and I used the source image for the same circuit board mask that we stuck on the phone. Once I had that in place, it wasn’t too difficult to use it in OpenSCAD. Check out the GitHub repo for details.
I did a couple of test prints on the MakerBot to make sure everything fit together, and it looks like it is working pretty well. I haven’t done another print with the logo, but judging from the generated STL, it is going to be much more involved than the basic prints.
When I added the logos, the STL went from about 300K to over 2MB. I’m hoping that the print itself will be stable enough that the logo won’t lose resolution and look bad. We’ve got a new stepper motor extruder ordered for our MakerBot, so that may help a little bit with the resolution.
The next project is to get this puppy to dial out. We’ve had a few suggestions, from converting the pulse dial to DTMF using an Arduino Teensy to hooking up a Blue Box with an acoustic coupler. Right now the easiest way to use it is to dial out on a different phone, and then pick up the handset. That really isn’t all that much fun. I’m leaning towards the acoustic coupler method, but early experiments with DTMF generators on our cell phones didn’t go too well, so we may have a bit more work cut out for us. The Wikipedia article says that blue boxes no longer work due to changes in the switching infrastucture, which… ahem… anecdotal evidence would tend to confirm.
I got my Raspberry Pi (model B) in the mail a few weeks ago, and I’m just starting to dig into it. I ordered from Newark/Element 14, and got it in just under 2 weeks. They’re quoting quite a bit longer, so it was a bit quicker than I expected.
If you’re not familiar with the Pi, it is a $35 700MHz ARM processor with 100Mbps Ethernet, HDMI, composite video, 1/8″ audio, dual USB, SD card reader, and a number of 3.3V GPIO pins. There are several different Linux distributions available that run on the device. The model A is about $10 cheaper, and doesn’t have Ethernet.
I’m a Debian user from way back, so I was pretty happy that there was a Debian release for the Pi. I’m currently running on a 2GB SD card that I had lying around, but it is a fairly tight fit, so I’d suggest (and I believe they do as well) that you go with at least a 4GB card.
Out of the box, I was able to get the GUI running and run some basic applications. SSH access is also enabled, so I was able to hook the board up to my switch and access it over the network for package management and command-line tools.
I was extremely happy that the distro included native packages for ARM. I run DD-WRT on my switch at home, and the busybox packages are a bit limited for my taste.
I’m thinking about running Nagios on the board and breaking out the GPIO pins to show some Nagios metrics on a LCD screen or LED bar graphs. I’ve done LCD stuff with the Arduino, but having Linux on the board itself really gives me a lot of flexibility on generating the data to be output to the screen. I’ve been looking at the elinux wiki for reference on how to use the GPIO pins, but haven’t really done anything with it so far. I’m a bit nervous about interfacing directly because these boards are a bit pricier than Arduino boards, but the GPIO pins are supposed to be able to source 500mA, so that should be plenty for what I’m trying to do.
Love to hear your thoughts on what you’re planning on doing with your R. Pi in the comments!
|From Workshop 88|
At last week’s meeting, our expert in all things CNC, Branden, was around for the last meeting before his move to Boston. (We will miss you, Branden!!) He was, however, kind enough to show us how to work the LinuxCNC distro software in order to get our Shapeoko running when we get the parts. (See the above video.) We are expecting the parts to arrive in the next two weeks. Very soon we will be milling parts! What will you make with the CNC router?
Thanks to the increased traffic from the Hack-a-Day readers, our kickstarter is starting to grow closer to being funded. It’s great to see that the post on HaD really emphasized the educational component of the HSIS challenge. Every time we get a $100 pledge, a kit that will go to a school somewhere in the country is 1/3 funded.
What can you do to help us engage kids in science exploration?