NERP^2 = Hardware: From Concept to Retail && PiAQ: Indoor Air Quality Sensor


Next Monday at NERP we’ll have a double feature. We’ll hear part 2, of Ste and Nicks’s story of adventure in bringing a successful consumer product to market. Part 1 was about technology, and part 2 is about the _business_ side of bootstrapping HD Retrovision ( Also on Monday, Dave Conroy will tell us about the PiAQ Open Source Indoor Air Quality Sensor for the Raspberry Pi (


About HD Retrovision:
Nick and Ste have been friends since 1999 and both share a passion for playing the (now retro) video game systems that they grew up on. Since then they’ve both studied Electrical Engineering at University, and are now business partners in a company called HD Retrovision that is dedicated to improving the modern day experience with retro consoles while making it accessible to as many people as possible. In this presentation, Ste and Nick will walk you through the ups, downs, and lessons learned while taking a college project and turning it into a profitable company. This talk will cover how they took the idea for HD Retrovision’s Genesis and SNES cables out of the lab, got it funded, and eventually mass-produced overseas.

About the PiAQ: As an R&D Engineer for NAR’s Center for REALTOR® Technology & CRT Labs, Dave Conroy investigates emerging technologies, educates NAR members & the public through presentations, webinars, blogs and podcasts, and develops products for use by members. He’s presented to REALTORS® on the national, state and local levels. The PiAQ is an open hardware and software indoor air quality sensor developed by the National Association of REALTORS’ CRT Labs. The goal for this project is to make information about the air people are breathing more accessible.

About NERP:

NERP is not exclusively Raspberry Pi, the small computer and embedded systems interest group at Pumping Station:One in Chicago. NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago. Find NERP and Pumping Station:One at

Doors open at 6:30pm. NERP is free and open to the public. Ed Bennett ed @ kinetics and electronics com Tags: electronics, embedded, NERP, Open Source, raspberry pi, hackerspace, Beagle Bone, Pumping Station One


10 2016

NERP Tonite! Google Summer of Code students build projects

Tonight at NERP, Drew Fustini will be sharing highlights from his presentation at Maker Faire New York 2016.

Drew explains How Open Source software and Open Source Hardware intersected in several BeagleBoard based projects done for the Google Summer of Code.  “Google Summer of Code is a global program that offers students stipends to write code for open source projects.”  These students’ projects demonstrate the synergy of devices and the code that makes them what they are.

NERP is not exclusively Raspberry Pi, the small computer and embedded systems interest group at Pumping Station:One in Chicago. NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago. Find NERP and Pumping Station:One at


Doors open at 6:30pm. NERP is free and open to the public. Ed Bennett ed @ kinetics and electronics com Tags: electronics, embedded, NERP, Open Source, raspberry pi, hackerspace, Beagle Bone, Pumping Station One


10 2016

My first project, upcoming Doctor Strange movie prop replica

Doctor Strange movie prop replica design pictures

Progress from preview to display of Doctor Strange movie prop replica.

Thanks to everyone who volunteers training and care for the laser cutter. My son and I will have a blast taking these to the opening night.


09 2016

Free Workshop: Earring Exposition




When: Saturday, October 1, 2016, 1:00 pm – 3:00 pm
Where: Arts Area (upstairs) Pumping Station: One 3519 N Elston Chicago, IL 60618

Drop in and make a pair of earrings for yourself or as a gift for someone! This is a very basic form of jewelry assembly, no prior experience is required. Learning this skill may help you financially as the “winter holiday gift season” of various faiths approaches.

Beads and findings will be supplied in nickel-free gold and silver costume metal. Bringing a pair of basic round nose pliers will be helpful if you have your own. Expect total time commitment to be in the range of 10 to 20 minutes. Please limit one project per member so the maximum number of people can participate.


09 2016

NERP Tonite! Improving the Retro Gaming Experience

Ste Kulov is Lead Design Engineer at HD Retrovision. Ste (known in NBA Jam as STE) was born and raised in the suburbs of Chicago and spent most of his childhood with his hands glued to a SNES controller. Like so many life-long nerds, Ste went to school for electrical engineering and became an expert at working with circuits. His passion for working on really cool engineering projects is second only to his obsession with video games. Ste conceived the original idea for HD Retrovision in his engineering design class to solve the world’s most pressing problem: allowing gamers to play their old systems on TV’s that don’t have the right inputs. [NERP Note: HD Retrovision cables are analog circuit devices. The HD Retrovision circuit board is molded into the cable.]

PS:One knows Ste for being a really good teacher. We wish he could find time to do more analog and fpga circuit classes (hint, hint).

A vital aspect of manufacturing is testing and quality control. Someone has to do it, and they need test instruments, test fixtures, custom software, and detailed written test requirements and procedures. Ste had to design a turnkey QC system for use by his contract manufacturer. The HD retrovision circuit itself is all analog, but the QC system is FPGA based. At NERP tonite, Ste will explain how you QC a cable on the other side of the world.

NERP is not exclusively Raspberry Pi, the small computer and embedded systems interest group at Pumping Station:One in Chicago. NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago. Find NERP and Pumping Station:One at



Doors open at 6:30pm. NERP is free and open to the public. Ed Bennett ed @ kinetics and electronics com Tags: electronics, embedded, NERP, Open Source, raspberry pi, hackerspace, Beagle Bone, Pumping Station One


09 2016

Mandolin Plates on the ShopBot

My name is Ralph, and I’m an amateur luthier and PS:1 “starving hacker”.

I make all kinds of instruments: guitars, ukuleles, bouzoukis, and more, but my favorite thing to build is mandolins.  They are far and away the most difficult instrument that I make, and require a level of craftsmanship not found in the simpler instruments.

There’s only one real downside to building mandolins— the carving.  Mandolin plates are made from 1” thick stock, carved into a very precise dome shape ranging from 3mm thick at the rim up to 6mm thick at the bridge.  Making the plate accurately is the key to getting a good tone from the instrument: too thick and it sounds “dead”, too thin and the top can’t withstand the force of the strings.

To make the plates requires a set of inside and outside templates that show the proper curves (making these templates on the laser cutter was a primary reason I joined PS:1), using carving gouges to get close the the final shape, and then curved planes and scrapers to get the dimensions exact.  There is about 40-50 hours of carving and scraping that go into a set of mandolin plates.  To make things worse, the back plate is made of hard maple, which is VERY difficult to carve.  Even with leather carving gloves, my hands are a mess of blisters and callouses after making a plate.

When I saw the CNC routers at PS:1, I was immediately struck by the idea of using CNC to produce a rough mandolin plate.  Even if I would still need to scrape to get things perfect, the hard carving work (and blisters) would be taken care of by the machine.

Thus began a year-long journey of discovery…

I learned about CAM, and taught myself to use Fusion 360, only to discover that this 3D modeling stuff is HARD.  I managed to turn out some pretty simple models for bridges and headstocks, which I was able to make on the Shapeoko and ShopBot, but every attempt at modeling a mandolin plate failed.

After flailing around for many months, I discovered the Fusion 360 meetup (sponsored by Autodesk and held at PS:1), and everything changed.  With the help of Autodesk’s Michael Aubrey (Fusion evangelist), and PS:1’s resident CAD experts, I improved my skills to the point where I was able to make a reasonable model of the top plate for an A-style mandolin.


Last weekend, I got to test the model on the ShopBot!  The initial version is in MDF, just to test the model and the machining commands.  Once everything is tweaked, I will do the real thing in Sitka spruce.

Since the plate needs to be machined on both sides, I needed to create a fixture to align everything.  It’s a pretty straightforward plate, with two alignment pegs that match holes drilled into the ShopBot wasteboard.  All of the shaping was done with a 1/2” round-nose bit running at 12000 rpm and a chip load of .35mm.

The inside is machined first, referencing the stock top.  It uses a pretty simple adaptive pocket to remove most of the waste, followed by a spiral with a 1mm overlap to take things to the finished size.


You’ll note that the pocket is not centered in the picture— my origin was in the wrong place in my model.  I fixed that, and the second attempt came out much better.  There is still a bit of scraping/sanding to remove the machine marks, but that was to be expected.


After the inside surface was machined, I flipped the workpiece over and re-registered the Z axis to the bottom of the piece.  That way, I know the thickness of the part will be accurate even if my stock thickness is off by a little bit.

Once again an adaptive pocket removed most of the stock, starting with a channel around the rim.


After the rim was rough-sized, the “hump” was roughed in.


A second pass of the adaptive pocket got the rim down to 4mm thick, and smoothed the transitions.


Just as with the inside, the finishing step used a spiral to clean the surface and eliminate the tool marks.  The net result was quite good, and will need only a bit of scraping to finish


After all was said and done I swapped in a 1/8” straight bit to cut the outer profile and f-holes.


Cutting off the excess stock left me with a quite nice-looking mandolin top plate!  Total elapsed time (not counting my initial screwup) was about 90 minutes.


Putting my micrometer to the finished product, the results were better than I expected.  Thickness is accurate within 1mm across the entire profile, with most areas within 0.5mm.  That leaves only a bit of scraping to get things perfect!

Next weekend… the real thing, in sitka spruce.

Many thanks to Michael Aubrey from Autodesk, Ray Doeksen and Andrew Carmadella from PS:1, and all of the Fusion 360 Meetup crew that helped me along the way!  I’m still a modeling rookie, but I’ve come a LONG way with your help!

Ralph Brendler


09 2016

A Light Diversion


In the last days of Radio Shack, I was in a store on Michigan Avenue when I spotted, buried amongst the disassembled shelving units and discarded phone cases, a small red box that turned out to be an Arduino-based soldering project, the 2770158 LED Cube ( I bought it for something like $5, took it home, and promptly put it on the shelf as a project I’ll ‘get to’ at some point.

The honest truth is that I was somewhat intimidated by the soldering; it’s a 3x3x3 cube of LEDs that are soldered together and the lights were smaller than i was expecting, and looking at some pics of the final result, I resigned myself to likely screwing it up and at best hoping that I might learn something from what I assumed would be a complete failure. So I somehow justified to myself that, in order to not waste my $5, I shouldn’t actually try to make the thing I spent $5 on.

At some point I hit myself with a clue-by-four and realized the stupidity of my situation; accept the possible loss of the $5 and actually try instead of fretting about what-ifs. So I took the kit to PS:1, sat down in the Electronics area, got out the soldering iron, magnifying glass, and went to work. It took a couple of hours, and I was certain, absolutely positively certain, that, even though it looked right, there was no chance that I had actually gotten the leads all wired together correctly, especially the ones in the middle that were extremely hard to reach with the big tip of the soldering iron. Okay, well, only thing left was to actually plug it into the Arduino Uno I had, load up the sample sketch (available in the RS GitHub repo above), and see what happens.

I fired up the Arduino IDE, loaded the sample sketch, hit upload, and all of a sudden all the lights came on as it started through the canned routines. I was initially skeptical, checking every single light to see which one was never lighting up, and all of a sudden it dawned on me that I had actually done it, all the lights actually lit up as part of the demo routine, and HOLY CRAP I MADE A THING AND IT WORKED!!!!1111

And then in my excitement I dropped it, ripping the USB cord from the Arduino, and landed lights-down on the floor. Well, of course I did. Of course I broke it, right? But as I checked the connections, nothing had come loose, there were no broken connections. I plugged the Arduino back in, and sure enough, it happily came back to life and started going through the routine. Whew!


So I resolved to make this truly my own; running a demo program that I didn’t write was not ‘finishing the job’. I remembered the QBasic ‘Snake’ program that drew a line bouncing around the screen, hitting the edge and then randomly turning and going off into another direction. Ah, but this is a cube, in threeeee deeeeeeee, so the challenge would be that more interesting, especially as I resolved to sit down and actually try to implement it without any help from the Internet; a three-dimensional matrix of lights, translated into C++.

This is where I remembered a line from Top Gun that went something along the lines of “Our pilots had become dependent on missiles” as a reason for loss of dogfighting ability. (And then I got that Everly Brothers song stuck in my head). Well, writing C++ for years, I had become dependent on the containers provided by the Standard Template Library (map, vector, etc.). While the Arduino is programmed using C++, it’s really a pretty small subset of C++ (which sort-of-kinda-not-really makes sense) and the STL is not available; go ahead and #include <map> all you like, all the compiler’s gonna do is complain. So I knew I’d have to regain some amount of dogfighting capability and do all the array/matrix stuff in pure C. So I decided the best way to keep myself honest and regain some of the skills I think I used to have, I created a C file in Vim (using Emacs always made me angry, straight-up I hate this, whatever this is), wrote the program, saved, compiled and ran straight from the terminal prompt. Again and again and again.

One of the biggest problems was forcing myself to get past the ‘sheesh, this woulda been easy to use <insert some STL thing> here’ and just focus on getting the values in the right cells of the matrix. It took a few hours to get the algorithm right, but pretty soon I had it spitting out numbers that seemed right, but how was I gonna know that it was right?

This is where I decided to make a quick diversion and build a virtual version of the matrix in OpenSCAD:


Using this model, I could walk through the output of the program and verify that the snake was truly moving correctly around the matrix. I rotated the model around, checking that the numbers were right and HOLY CRAP I MADE ANOTHER THING THAT WORKED!


The last thing to do was to actually get the program to work with the LEDs. This is where the spartan documentation of the original Radio Shack code became a problem; the sketch did a passable job of explaining how the lights were addressed, but the examples were all arrays of pre-baked values without having to do anything dynamic, and my program was all dynamic. I studied how the demo program worked, started fiddling with the values, and discovered how to set the bits in the right way to turn on individual lights, on specific levels. From there I modified my C program and added some code to translate my positioning, which turned out to be the mirror opposite of the way the lights are addressed; I solved the problem by physically turning the Arduino around so I was looking at the other side. Problem solved!)

I uploaded my sketch to the Arduino and it suddenly the lights were lighting up in what appeared to be a snake moving around the matrix. HOLY CRAP I GOT IT TO WORK!!!!!!11111


This is a long post for what amounts to a small light toy, but whilst I was feeling rather verbose (a consequence of sitting and waiting for an unrelated program to finish), I can’t emphasize how foolish I feel for not starting all this earlier; fear of failure is a very, very powerful emotion and if there’s a TL;DR in here somewhere, it’s that it is always better to try and fail than to never try at all, which is something PS:1 has done a very good job of teaching me.


The code is available at


08 2016

Spacecats Rocket Build!

A good friend of mine had the vision to make a memorial to lost cats at Burning Man 2016. It would be a whimsical project with a deeper side to it to honor our fallen feline companions.  To see more of what is behind the project can go to see the Spacecats Indiegogo at . I was asked by her to assist with creating the rocketship part of the project for the intrepid spacecats. I just starting doing CNC work this year and leaped at the opportunity to further improve my skills with a big project. Over a period of 2 months many models were created to arrive at the final form. I will detail the workflow for this and share some of the iterations!

It all started with Fusion 360, a great program for makers, to create a basic rocketship model. Well, I thought it was basic but my inexperience made it a bit harder than expected and went through many hours of “learning time” to arrive at a model I was happy with. From making the 3d model in Fusion 360, I then took it to 123d Make to have it piece together in radial slices so that it can be put together in real life! With the parts generated from 123dMake I was able to create some laser models to show my friend and get her input for her vision. As you can see it took about 4 times to get it right. These models were done 1:10 scale then 1:7 scale. it really helps to have something in front of you to decide what will look best.


After finally arriving at a model that was good it was time to bring it to the shopbot for a 1:2 model (that is also one of the indiegogo rewards!). There was much dialing in to make sure that the slot fit was tight but not too tight to be able to fit the pieces together.  Found that adding in .01 helped immensely to get the perfect fit. I did many test notch pieces to ensure the fit. One problem I had was making the test pieces too small so it did not get the full effect of sliding all the way into the wood. I found that making them larger really helped. It paid off to prototype and make test pieces , saved me from wasting many materials , especially when I moved to the more expensive wood!  Finally, we had something that the Spacecats seemed somewhat happy about – other than that orange tabby Floyd at least!


Also learned how to use a V bit for this project , very challenging to get the right font in so that it looks nice but was not too thin. This is the plate with the names of departed cats.


And finally , was able to do the full-size model that will go out to burning man! They were displayed at an event last weekend that was a Hawaiian luau, they seemed pretty pleased with it if I do say so myself!


Thanks to everyone at PS:One for the patience to answer many of my questions and excessive use of the shopbot to dial this project in 😀

If curious about the indiegogo project and the other elements of the installation can check out the page at Spacecats . And if going to Black Rock City this year, look for some spacecats in the deep playa!


07 2016

How to Wear a Cabochon with an Irregular Shape



Now that members have made a bunch of fused glass cabochons this week, what can we do with them? You can make several cabochons and mount them on your own Medieval style gemstone covered book, hot glue it onto your stapler at work and really establish that one is yours, make some really shiny refrigerator magnets but jewelry is the most common application.

I encased my cabochon in a mount by free form hand weaving seed beads. This piece used different stitches and a strong nylon mono-filament thread. The beads are 11/0 size Czech glass and 15/0 size Japanese Miyuki glass. I encased the whole cabochon because the back of the fused glass was rough and uneven.




Other methods to make jewelry with a cabochon with an irregular shape are:

  • You can stitch bead embroidery around the cabochon securing it onto a backing of leather or heavy fabric. This will be similar to my example but simpler in its execution.
  • Glue on a bar pin back to wear it as a pin.
  • Glue on a bail to wear it on a chain or cord. There are many colors, sizes and shapes of ready made jewelry bails.
  • Wire wrap the cabochon with jewelry wire.

Given the resources we have at the space, someone could even 3D print a setting for their piece and then cast it in metal!







07 2016

The Joy of Melting Glass in a Microwave Oven



Samuel and Sylvia Sion brought in to last night’s member meeting an amazing impromptu class on fused glass. Glass usually has melting points higher than metal, yet there are these new miniature kilns that work inside of a conventional microwave oven! This makes fused glass work far more accessible and affordable from past days of using a larger plug-in electric kiln for hours. The time to melt an art glass cabochon was usually under five minutes with about 45 minutes needed for cooling. The larger kiln fit several pieces at once.

The microwave being used for glass fusing needs to be dedicated to art use only and never used for food again. (Cadmium and other pigments used for colorants are toxic, so this is a needed safety precaution.) Care needs to be taken to not overheat the microwave and destroy it, so letting the door stand open and the unit cool off between rounds of fusing glass is needed. Also, microwave kiln shelf paper needs to be placed on the base of the kiln to keep glass from melting onto the surface the kiln and destroying it. Heavy weight welding gloves worked as oven mitts to transfer hot kilns and the kilns rested safely on our ceramic fire bricks to cool.

Glass specifically made for fusing needs to be used for projects, like the brightly colored Dichroic glass example I made below. Dichroic and fusing glasses are the shiny, beautiful art glass pieces you always see in jewelry at art fairs. The price for making them yourself is very reasonable with this new method; you can buy enough to make several pieces for $20-$30. The kilns and tools to get started are being added to the small metals area and will be available within the following weeks.




07 2016