## Thursday, December 31, 2015

### Brewing a Carob Kitchen Sink Stacktrace Porter or A Comedy of My Many Errors

I decided to brew a batch of beer and I wanted to use up any random brewing ingredients I had, so I decided to make "Carob Kitchen Sink Stacktrace Porter".  I had made a carob porter before based on a recipe in The New Complete Joy of Home Brewing "Goat Scrotum Ale" p. 199, so I started from there again, with a few modifications based on my current inventory.  I added "Stacktrace" to the name because a stacktrace is the list of everything that happened during execution of program - generally looked at when something went wrong - and things going wrong is a key component of this brew.

## Wednesday, December 30, 2015

### Brewing a Second Batch of Mead

We brewed our first batch of mead back around Fall 2009, we were motivated to give it as a wedding present to my sister-in-law who we knew was getting married in 2010 - that gave us a year to let it age.  It turned out pretty well, but it was much sweeter than we would have liked it.  Over the next few years, we noticed as time went on the sweetness diminished and the mead got better and better.  We're down to our last bottle, which is living in my mother-in-law's fridge, so I decided to brew another batch and try to make it less sweet at the outset.

## Tuesday, December 29, 2015

### Mini-Foundry to Melt Aluminum, Construction and First Attempted Use

My friend Phil pointed me towards this YouTube video in which Grant Thompson (GT) demonstrates how to build a mini-foundry that you can use to melt Aluminum at home and out of common materials, so I decided to try it for myself.  This post will describe how I built it, largely following what GT did in his video demonstration, and a first attempt at using it to melt aluminum.

## Wednesday, December 23, 2015

### Welding a bottom bracket to my bike

The bottom bracket on a bike is essentially what connects the pedals to the frame and allows them to rotate.  I had replaced the bottom bracket on my bike awhile back, and then a few months ago it came loose.  I initially tried just tightening it down, then tried locktite (red); neither worked to hold it in place.  I took it to a bike shop and asked them about cleaning up the threads, they looked at it and said, "What threads?  There's nothing left."  At that point I decided to try to weld it (TIG welding), but it was ultimately not successful - the welds were very messy, the arc was behaving erratically, and although initially I was able to ride the bike, after~ 4 rides to and from work the welds broke and I was back to where I started.  This post describes my second attempt at welding, which I think will ultimately be more successful.

Edit:  I forgot to mention - I did this work at Artisan's Asylum in Somerville.  They are fantastic!

## Saturday, December 19, 2015

### Attempted repair of a FitBit Flex

I had an old Fitbit Flex that had stopped working so I decided to try to fix it. (Important note:  Fitbit had given me a free replacement - that's pretty great of them.  I tried this fix after losing the replacement).

The problem I had with this Flex was that the battery got low and then it would not recharge.  My idea was to charge it "manually" by somehow creating a better connection to the Flex from my DC power supply.  Using my multimeter I wasn't able to measure any voltage across any combination of the 3 pins, so my next step was to try to determine which pins should have power or be used to try to charge the Flex.

## Saturday, October 31, 2015

### Electric Imp Thermostat

I decided to build a thermostat out of an electric imp, which will then be easily controlled remotely and with arbitrary complex programming based on any conceivable input / data.
 Starting components, from upper left: electric imp, TMP36 temperature sensor, solid state relay, electric imp breakout board, perf board.  Not pictured:  op-amp

## Tuesday, July 14, 2015

### Shortest path - around the circumference or rectilinear path through

I was out running and I was faced with this approximate situation:

## Tuesday, June 23, 2015

These are thoughts I've had about traffic, basically since I first started thinking about it when I first really experienced it in Philadelphia in the mid-90's.  One thing that has really surprised me is that during the TD 5 Boro bike ride in New York City (Spring 2015), the bicycle density was so high that conditions were comparable to car traffic - and I saw the same patterns of behavior!

### Why I bike to work and around in general

This started as an email to my friend Kevin, but then I realized I'd like to share it more broadly and keep it somewhere I could find it more readily.  It's the rationale and data I've accumulated about biking.  The vast majority of my commute is by bike - I live in Boston, MA and I bike year round, mostly regardless of the weather (snow, rain etc.).  I also bike for fun occasionally on the weekends, but this post deals with commuting.

## Wednesday, March 11, 2015

### Create a RAID using one raspberry pi then transferring it to another

Build the array on a raspberry pi 1 that is already running a raid (level 1) array
• connect two 2-TB drives via powered USB hub
• They appear as /dev/sdd and /dev/sde
• use fdisk to delete the pre-built partitions, create new partitions using defaults that are for linux and fill each disk
• created array:
 mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sdd1 /dev/sde1 

## Monday, March 9, 2015

### Raspberry pi 2 and the case of the unreliable USB ports

My newly purchased raspberry pi 2 did not recognize external harddrives:
• There is a powered USB hub for the drives - same make & model as I use successfully for the pi version 1
• Same manufacturer for the drives, but they were 2 TB instead of 1 TB (each)
the command lsusb reported information, but it was regardless of whether the hub was plugged into the pi or individual drives were plugged in to the hub:
 Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
dmesg provided the most information - sometimes no message when plugging in the hub, sometimes limited message saying the hub had been found then disconnected (when it was still plugged in):

## Sunday, March 8, 2015

### A hilarious economics post

This post:
https://medium.com/@yichuanw/a-dynamic-theory-of-romantic-choice-6e275270da93

is about explaining why "all the single people are crazy" and "all the good ones are taken".  It is hilarious and mathematical.

It would be awesome to fit that model with data from OK Cupid...

## Monday, March 2, 2015

### Electric imp temperature sensors

After experiencing many burst pipes (in our baseboard heaters) I decided to build some temperature sensors.  My friend Phil recommended using the electric imp microcontroller and quickly found a tutorial on how to use it to make a temperature sensor:   https://plot.ly/electric-imp/tmp36-temperature-tutorial/

In the above the general concept & required components are spot on, but some of the specifics / details are off.  Here's what I did, which is the same in outline but differs in some specifics (which I hope are accurate).

Parts: