All posts by Kevin Osborn

About Kevin Osborn

I’m a Maker and ardent amateur educator. I also love to create art, hack electronics and do geeky activities with my kids.

Yogurt Science Style!

Ok, If you only come here for electronics, and 3D printing, look away, but my love of making also extends to food, especially if it’s preparation involves science-y gadgets and biological processes. I’m a big fan of fermentation, and while I no longer brew beer, I regularly make fermented pickles, hot sauce, sauerkraut and …. Yogurt!

I’m known amongst my friends as a Sous Vide Evangelist, spreading the word of the best kitchen gadget ever: The Immersion circulator. I’ve cooked lots in it but it took a while for me to realize that it would be great for short term culturing of fermented foods. Yogurt is soo easy to make, and you can chose your favorite milk. I personally use High Lawn Farms Jersey Cow, Whole milk. High in protein, fat and deliciousness!

  1. Bag the milk in a ziplock bag. The cheap vacuum sealer I have is best for drier foods, so I just use a gallon freezer ziplock. Check it as they sometimes leak. Use either the water immersion method or edge of table to get most of the air out. If I’m careful, I can usually get a half gallon in the gallon bag.
  2. I forgot to take a picture of this step, but pre-heat your immersion bath to between 180 and 185F. Cook for 1 hour. This apparently changes some of the proteins and makes them more available for fermentation. When it’s done, I chill it by putting the bag in a bowl and pouring cold water on it, waiting until the water is warm, pour out and repeat. It should be warm to the touch but not hot. If you have an infrared thermometer, make sure it’s below 120F.
  3. Add 1/4 cup good plain yogurt with live culturesadd yogurt
    Purge the air again, and reseal. Squish around on the table a bit to disperse the wee beasties.
  4. Change the water (it’s too hot!) and reset the Immersion circulator for between 110 and 116F. I tend to use 112F.

    Let it ferment for 6 hours or more. I generally stop at 6 hours. Longer is more sour if you like it that way.
  5. When it’s done, you’ll see lots of solids and separate whey.

    You can just re-mix it up at this point if you like more runny yogurt. I generally try to pour off as much whey as I can (save it, more on this in another post). This makes it more “greek like” though I don’t go crazy and strain it through cheese cloth. I just pour as much out of the bag as I can.
  6. Whisk or use an electric mixer to smooth it out. It is a little lumpier than commercial yogurt, but once you try it, there’s no going back.

 

Holiday Ornament Design Challenge

Over the Holiday break, I challenged my family to design some ornaments for our tree. So far, only Mason (17 year old son) rose to the challenge, and I think he did very well indeed.

He did the designs in OpenSCAD, and at first hardcoded all the measurements until I encouraged him to make the designs fully parametric. This piece was designed to accept a light (from the string lights on the tree) in the bottom. Printed in Natural PLA with about 15% fill, giving it a kindof stripey, plaid texture.

This was printed without support on the Ultimaker 3. The very inside top is a little stringy, but hardly noticeable, and very easy to clean up.

The second design was really the first one he did, and isn’t fully parametric. You’ll have to scale it in your slicer, but it turned out pretty nice.

I printed it in white, thinking it might be fun to use a sharpie to color in the facets. This was printed with the PVA support.
I also printed it in transparent ColorFabb XT. I had a problem with the wipe tower, so the top was a bit messed up with mixed PVA and XT, which broke off, but a light fit into it, and I think it looks nice.

I encourage you to sit down and design with your family this holiday. You can get the sources for these at: http://github.com/osbock/HolidayOrnaments. Feel free to do some Pull requests to add your own designs!

For younger, or less mathematically inclined designers, I recommend Tinkercad.com, or I’m sure there are cool Ipad apps out there. Let me know if you have a favorite!

Building Access Security Research

I’ve been researching a lot of contactless payment, and authentication stuff for work, and thought I’d share some of the most interesting links. This post will focus on building access.

Building access

It seems like many building access keycard systems are pretty weak in terms of security. Essentially, many of them present an ID code that is checked against a database. If you can copy that code you can clone the card (replay attack). Also most of them use something called Wiegand signalling as their output which is just a protocol to decode, so if you can tap in, you can sniff or inject stuff pretty easily. There are more secure systems out there that use a cryptographic exchange, but the insecure systems are in abundance!

getksi.com blog — This is a company that sells a more secure building access system, so they’ve done a lot of competitive research about vulnerabilities of common building access systems.

bishopfox.com — Security consulting firm. hacked a long range reader to steal ID’s. Essentially used an arduino to listen in on the Wiegand output.

Jonathan Westhues — EE and software guy did a lot of reverse engineering of some badge signals, later created a whole platform for reading and spoofing badges.

Lasercast Activate!

I recently got my thumb reconstructed (due to Osteo arthritis). And my new cast felt like it could use an upgrade. Laser! I figure it will be a good addition to my mad scientist costume for Halloween. Chinese laser pointer from ebay or aliexpress (don’t remember, I have a drawer full of laser modules). Adafruit powerboost 500 basic (If I’d had the full one, it could charge too, but this is what I had lying around).  I designed a very basic platform in OpenSCAD, and stuck the board down with mounting tape. The enable switch is soldered directly to the board (I cut off one of the terminals.)

Both the laser platform and the activation button are mounted with Velcro (the cast is coming off…) the button is superglued to the disk that holds the velcro dot.

If you want to make it, it’s very likely that your laser module will be sized differently so edit the openSCAD file to  fit.

3D printed circle the same size as a velcro dot

First Video, and a few Quadcopter lessons learned

I had a lot of fun flying the 3DR Solo in the last couple of weeks, but after a while you just want to DO something. Until I develop my “copilot” add on board to activate some cool add ons and sensors, photography is the obvious thing, and my bundle even came with the stabilization gimbal. I was planning on buying a “fauxpro” from MCM electronics but found out the gimbal is really “locked” in to Genuine GoPro ™. I could probably hack it, but the biggest advantage of using a real GoPro is the expansion connector on the back allows you to start and stop video, take pics etc. from the remote. So I gritted my teeth and plunked down $250 at Costco.com on a GoPro Hero4 bundle that included an extra battery and SD card.

Here’s my first flight video:

I’m very pleased with the video (shot at 1080p and 60 fps) though obviously, my control and shot planning skills need some work.

Shortly after this, I crashed and trashed 4 propellers (ouch$). I was running it on “cable cam” where you fly to different positions, record them and then you can run the quadcopter between those positions like it was on a cable. When I ran it to the end of the “Cable” it ended up being about 5 feet higher than when it started, got tangled in some wires, and crashed upside down. It sat there and ground the propellers to dust, as I didn’t know how to turn off the motors until it detected the crash (maybe a minute later).

Lesson Learned: Don’t expect GPS to get you exactly to a spot (it’s only good +- 3 meters at best) and don’t fly in a confined airspace unless you are really good and manually controlling it!

Other Lesson Learned: RTFM, except there was no FM! Well, online there is, and a quick web search revealed holding down a and b buttons together will cause an emergency motor stop.

3DR Solo of my very own!

If you’ve followed this blog, you know I’ve played with toy quadcopters and built one from parts. I’ve also built an FPV racing drone that I’ve only successfully flown twice.

For a long time I’ve lusted after a GPS drone capable of autopilot, especially after a demo by a neighborhood friend of his DJI Phantom 3. I think the DJI drones are pretty cool, but I hate that they are not open, and being both an Open Hardware guy, and never satisfied with factory settings, I really wanted open source.

3D Robotics, founded by former Wired editor Chris Anderson has been making open source autopilot drones for quite a while now, but they’ve been quite pricey, and don’t include a camera. I just couldn’t justify it.

My friend Michael Castor at  http://www.mcmelectronics.com/ clued me in to a sale at Bestbuy and I scooped up a Solo, extra battery, gimbal, extra propellers, and a backpack for $399 (plus tax). SCORE!

Note, last time I checked, the price just went up to $599, but you can still get the Solo for $399

Free 2 day shipping said it would be here Thursday, but the Solo came on Wednesday, and the rest on Thursday.

solo box

It was well packed, comes with battery, two extra propellers, transmitter,  and chargers for the transmitter and the battery. It comes with an eggcrate material carrying case that would probably do for a while, but I hate to think what would happen when it rains.

The backpack, which came later (and I may cover in a future post) is terrific."carrying case"

DJI, by the way also gives you “carrying case” packing, but in their case close cell foam, which would probably hold up longer.

Solo unboxing

Setting it up was pretty easy, download the app to my phone, power everything up. There’s a required firmware update before flying, and while it crashed my phone a couple times (I am suspicious because I have CyanogenMod) it took only about 2 minutes.

I don’t have a camera yet (I’m waiting for a new model of “fauxpro” from mcm electronics.) but It was amazing that I actually managed to work all week without flying. A quick stop at the FAA site to register, print a label for my Solo, then I did get out on Saturday, and I’m hooked!

Kevin flying his new Solo
Photo by Will Caldico0tt

Auto take off and landing are the bomb! The orbit mode was pretty easy to use, once I figured out how to set the center on my tiny phone screen. I ordered an acer tablet from ebay (about $70) and hope that will be better.

3DR recommends initial flights in a wide open area, and I concur. While it’s really easy to fly, it’s also hard to judge depth at distance when it’s flying near trees etc. The next day, I did manage to crash it, breaking 2 propellers, and chipping a third. The Solo was fine though, and shut itself down with the remote talking to me “Crash detected”.

Hacking potential

I wouldn’t have even spent $400 (and will likely spend even more) if it wasn’t easy to add my own hardware and software mods. 3DR makes this really easy, with a well thought out Dev kit python API, and well documented hardware expansion. Check it all out at: https://dev.3dr.com/index.html

What makes this really exciting, is the Solo (in spite of the name) actually has Two processors, a pixhawk flight controller, and a linux based computer. You can actually ssh to the drone, and store scripts for execution during flight.

I’m excited that you can even use OpenCV on the video stream from the camera.

Arduino Robot Class preview

I’m teaching an Arduino Robot class June 29 from 6-8pm at YouDoitElectronics in Needham, Ma. The cost is $99 and you get to take home the robot you build. I’ll show you how to use an Arduino to control DC motors, and read sensors to react to the environment. The robot we’re building will have a sonar sensor for distance, and two line detectors for following a line.
To register email your name phone number and number of participants to events@youdoitelectronics.com. Please include Arduino Robot Workshop in the subject line. You will receive a call back within 1-2 business days. Fee is required at time of registration prior to the start of the workshop. Once registration and payment are complete a reservation confirmation number will secure your spot.

DIY Rayguns!

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I’ve been going to Arisia (one of Boston’s Science Fiction Conventions) for several years. I always have a great time, and it always amazes me the amount of volunteer effort that goes in to providing amazing programming for everyone. This year I wanted to give something back so I came up with the idea of people building rayguns.

(NOTE: My extra kits are available in my etsy shop: https://www.etsy.com/listing/265475569/diy-raygun-kit)

Regular LED strip is super cheap when you order it from China. It normally runs off 12V, but a 9V battery lights it up just fine. I created a simple laser cut frame to put some LED strips, and then some cool laser cut acrylic disks to give it that groovy 50’s raygun look.

I bought most of the parts myself, but special thanks goes to my friend Jeremy Green at Charles River Maker for donating Laser time for cutting the kits. He’s your goto guy for design, prototyping and digital to physical services with laser cutting and lots of 3D printers!

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A switch makes the trigger, and there’s a fin with holes to add decorations.

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First cut a strip of LEDs. Mine consisted of groupe of 3 led sections.. Cut a strip of 5 sections, two sections on each side and one straddling the middle:

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next glue on the handle “dimensional” bits. These are mainly to make a recess for the battery, and maybe wrap the handle. Super glue works pretty quick, but you could probably use wood glue or whatever is appropriate for your frame:

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Glue the trigger button on, (kindof low, as the disks are pretty close. Actually I moved it down abit after I put the disks on (later step)

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Line up the battery clip and shorten the leads to connect one end (I chose the red, positive wire) to the positive contact on the LED strip. A small wire went from the negative contact to the switch and the other lead of the switch to the negative lead of the battery clip.

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Test, viola!

Next line up the disks where they fit. back them off and put a drop of superglue where each disks goes in order.

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The source files for laser cutting are at: https://github.com/osbock/Baldwisdom/tree/master/DIYRayguns

And now a few pics from the workshop at Arisia!

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