Category Archives: Making Stuff

AutoScope : Part 1 : Overview

Dr. Dan Kott, a member of our local maker community, came to us with a problem. He had come across a microscope automation project created by a pathologist in Australia. Because of other commitments, the Australian doctor was unable to complete the project, and Dan wanted to complete it.

The idea is this: automate an inexpensive, but good quality, microscope. In other words, motorize the stage. Instead of manually moving knobs, motors and a microcontroller would take the place of your hands.

Why do this?

  1. You can make the microscope joystick controlled. This means you can remotely move around a slide. Very handy in a teaching situation where a video camera is connected to the microscope and the teacher is pointing at an overhead projection.
  2. Samples can be “marked up” for reference. An automated scope knows exactly where X/Y are on the sample slide. Therefore, a physician can find an element of interest, say a cancer, note it’s location, then give the slide and location to a student for review. (“See position 1456, 2345 — that’s an abnormal cell wall.”)
  3. Slides can be automatically scanned. The automated microscope setup means that an entire slide can be photographed in very high resolution. Those photos can be “stitched” together to make a single high resolution image.

While Dan had some videos of the rig, and copies of the 3D models for holding the motors, there were a number of challenges. These included:

  • Creating gears which would fit onto the existing knobs of a common series of microscope.
  • Determining which stepper motor controllers and software to use.
  • Choosing a microcontroller and writing code for it.
  • Getting the basic setup to work, so that additional functionality can be added.

First stop: the gears.

RetroPie Showing Only “CHOOSE”

After building my Pi2 (for the living room), I decided that I’d use my old Pi1 for the bedroom. Just another image install and a new SD card and I’d be set.

Or so I thought. Last night I batch loaded a bunch of ROMs and find that RetroPie is either showing a black screen, a scrambled screen, or just the “CHOOSE” option. You can F4 to exit and restart, but same problem.

After deleting ROMs, paring down ROMs, etc I finally uncovered the issue.

At first it seemed that the quantity of ROMs was the problem (it is running on an older Raspberry Pi, after all). Was it the Master System? SNES? It was weird.

So I slowly re-loaded my ROMs. And the second I added ANY GBA ROMs it started acting up. Here’s why:

I was stupid. I forgot to double-check the install instructions for GBA games. You need to have a BIOS file for that emulator. I had done this on my Pi2, but forgot to do it on my Pi1.

What’s happening is this: Emulation Station attempts to generate screen backgrounds for each of the emulators. To do this, it needs to run the emulator (I’m guessing). It hit the GBA, didn’t find the BIOS, and failed in an unfriendly way.

Putting the GBA BIOS in the proper directory, like I should have done, has fixed the problem. Horray!

Fun Tech Learning Resources

Those who know me know that I’m not the World’s Biggest Fan of formal education. Too much pounding square pegs into round holes and whatnot. So, I’m always looking out for interesting ways to teach without the rote learning and boredom. Here are a couple of resources that might be of interest.

Twine

Those of us born in the pre-cell-phone days will recall the Choose Your Own Adventure (a trademark of Bantam) books — AKA CYOA or Gamebooks or Branching Plot Novels. I’ll use CYOA because everyone does.

The neat thing about these books is that you get to choose a path. Reading and interaction. Don’t like the one path? Go back to the decision point and try another. An interesting way to teach consequences to actions without being pedantic.

There are a number of tools out there that allow you to create your own — for consumption in a web browser. The best mix of free-and-easy is Twine. (www.twinery.org) You get a GUI with boxes. Each box holds text. You add decision points/links which ties the story together. The focus is on creating content, not programming — but it does — surreptitiously — teach some programming.

It’s very easy to use — a parent and young child can get the hang of it pretty quickly. Once you’re done, the result is an HTML page that can be viewed on any browser. There are plenty of Twine How-Tos, so I won’t recreate that wheel, just do some Google searches.

Personally, I prefer their “older” desktop version (1.4.2) versus their re-worked Web-Only version (2.0.4). If you accidentally refresh on the Web version, or your browser refreshes (like Android browsers love to do) then you lose work. Desktop version just seems safer to me.

One thing I’ve been searching for is a way to get Twine into an Amazon Kindle. Twine produces Javascript-heavy HTML, which is fine for browsers, but won’t work in MOBI formats. Haven’t had any luck yet, though. (There are other CYOA tools out there that say they can convert to MOBI, but they charge you $10 per conversion.) I’m thinking of either writing a conversion program, or my own version of Twine that natively outputs to HTML or MOBI-friendly. We’ll see if I have the time.

Scratch

Scratch is a programming language which should probably be CS 101 in all schools. Colorful user interface. Lots of programming without writing code, etc. Good for all ages, really. Check it out here: https://scratch.mit.edu/

Scratch has evolved from a desktop based tool that interacts with a “Scratch Board” (for Input/Output) to a pure web-based environment. I regret the demise of the Scratch Board, as it allowed you to have physical pushbuttons and whatnot, but the web tool can run on any browser (and works great on Chromebooks), so there’s something to be said there.

Squishy Circuits

Looking for a playful way to learn about electronics? A good start is Squishy Circuits. You need a handful of inexpensive components and make the circuits out of a home-made clay-like substance. It’s perfectly safe (just flour, water, salt, etc) and really helps you to visualize what’s going on.

Read more about making your own conductive dough, view a teaching presentation, and more at Squishy Circuits.

Kayak Running Lights

With the Texas Summer in high gear, it’s been necessary for us to get out either really early or late in the day. While it’s still pretty darn hot, the evenings are nice because you can watch the sunset and the bats emerge from the Congress Avenue Bridge.

The other night we found ourselves in complete darkness — without any running lights. While I wasn’t too worried about small boats — I did want the cruise boats to see us.

Having a bunch of LEDs on hand, and some PVC pipe — and not wanting to spend money of purchased lights — I came up with this:

DSCN3964 (Large)

 

 

 

 

 

 

It’s made out of 1/2″ PVC pipe.  The uprights are thick-wall (high pressure) — so they don’t flex. The bottom gets screwed into a board (painted exterior white) using a cap. White LED at the top, red and green on the sides.

That little part you see sticking out (under the LEDs) is where the batteries and switch are located. I found that 3V Lithium batteries fit perfectly into 1/2″ thin-wall PVC (but not thick–you must use thin). I used some caps, screws, and a spring to make my own battery holder. The black thing on the other end is a rocker switch. Since most of the parts are just press-fit, removing the batteries is easy — just pull off the little pipe extension.

Normally you’d want the red and green up front, and the white at the back (so the length of the boat can be determined). But for Version One, I just kept it simple and all together. Better to have some light than none at all. My next version will probably have the tall white light assembly in the back, with a smaller setup up front. My key is to have to lights tall enough, since we run so low in the water.

 

 

Cat Crib Stand

Our cats love the Cat Crib, but they really haven’t used them when attached under a chair. Instead, we made some inexpensive and easy to assemble stands for the cribs.

This version will make a unit about 20″ square and 34″ tall.

Here’s what you need:

  • Three 10′ pieces of 3/4″ PVC Schedule 40 pipe. This is the kind you get for plumbing. They are about $2.28 each at Lowes.
  • Four 3/4″ Schedule 40 couplings. $2.61 for a pack of 10.
  • Eight 3/4″ Schedule 40 90 degree Side Outlet Elbow. $1.60 each.

couplingelbow

 

 

 

 

Total cost will be about $22.25 + tax.

The only tool you’ll need is a saw. I do mine on a miter saw, because it’s so quick. But you can use a hack saw, sabre saw, or PVC pipe cutters (if you own them already). I would not recommend a table saw and definitely don’t use a circular saw — too dangerous.

  1. Cut eight pieces 18″ long.  This makes the size of the square and is the smallest size for a Cat Crib to work. I’ve make some with 21″ spans, and that works fine, too. You’ll use all of one piece of 10′ PVC pipe and some of another.
  2. Cut four pieces 28″ long. These make the legs. You can adjust to just about any height. As little as 6 inches, but I wouldn’t go over 28″ (it becomes too tippy). You’ll use most of one piece of a 10′ PVC pipe.
  3. Cut four pieces 3″ long. These are used, with the couplings, to keep the crib from slipping down. Don’t go any less than 3″, or the straps won’t fit. Anything from 3″ to 6″ is fine.

Assembly

  1. Use four 90 degree side output elbows and four 18″ pieces of PVC pipe to make a square. Make sure the open outlets all face the same direction (ex. “up”) and that everything is square and tight. Tap together the pieces with a rubber mallet for a tight fit — but don’t bang too hard, or you’ll crack the elbows.
  2. Repeat the above step to make a second square.
  3. Attach a coupling to the end of a 28″ piece of pipe. Attach the 3″ piece to the open end of the coupling. So, you have 28″ + coupling + 3″ piece.
  4. Repeat the above step for the other three legs. You’ll have four in total.
  5. Using the four legs, make an elongated cube using the two squares. I usually put the four legs into one of the cubes, then align the other on top, and tap together. Make sure that the couplings (near the 3″ piece) are all on the same side (ex. “top”).

You’ll notice that I didn’t use any PVC cement on this. I’ve found that with 3/4″ you really don’t need it. The friction fit is pretty strong. And it allows you to play with the height of the unit, if you want. If you find it’s not tight, then use cement.

That’s it. Now, hang the crib from the upper part (the couplings keep it from sliding) and you’re set. Very simple design and easy for kids to assemble.

DSCN3967 (Large) DSCN3966 (Large)DSCN3970 (Large)

 

 

 

 

 

 

 

And remarkably sturdy. Our 20# cat jumps into it without a problem. If you are going to have it outside, just drill some holes in some of the bottom pieces and screw into a deck. Or stake down. The cribs aren’t rated for outdoor use, so I’d keep it under cover. Or, make your own, out of canvas or whatnot.

Here’s a shorty version I made. This one is even easier, as you don’t need a bottom square.

DSCN3968 (Large)

 

 

 

A modified version, using 90 degree elbows at two corners. So it would fit around the back of our Precor.

DSCN3969 (Large)