Repair of Cracked Plastic Clip

A crack developed in a plastic clip holding a window shade.  The rest of the clip flexed so that the entire shade tended to fall to the ground when we tried to raise or lower it.  To hold the crack tight I drilled a couple of holes for four-penny nails and tensioned across with safety wire, avoiding areas where screws pass through to hold the clip to the house and where the clip fastens around the shade.

clip repair

BrewPi fermentation controller build

After homebrewing for so many years, I knew fermentation temperature control was something that ought to be added to my capabilities.  I’ve made controllers from the STC-1000 box but the BrewPi was attractive for the detailed control offered and logging abilities, and it seemed like a neat challenge.

I ordered the parts from BrewPi in Europe but decided to omit the pretty enclosures offered by the creator, Elco, as I wanted to get everything in one box to the extent possible.   The supplies from BrewPi included two nice solid state relays, LCD display, temperature sensors, and parts to solder up the Arduino shield (an easy soldering job).  I ordered the Raspberry Pi and a WiFi dongle for it, plus the Arduino, separately from Adafruit.

I decided to power the Pi and Arduino through this pluggable brand USB powered hub, which also connects the devices for data.  This worked well in my first tests show below, where I got the temperature sensors working to control the SSRs though the BrewPi software.

brewpi testing

I ordered this box to use as an enclosure, which is a little larger than necessary but not massively so.  It held everything (including the power supply for the USB hub, fused IEC power inlet and switch,  and AC outlet for heating/cooling) with some room to work, and is nominally waterproof (NEMA) but that is not something I plan to put to the test, especially after I made holes for the sensors, display, etc.

brewpi assembly

The temperature sensors are on a neat three wire digital bus.  I used old mint tins to house the distribution boards as you can see in the below photo, showing lines for the fridge and beer temperature sensors.  The right carboy has a thermowell to get the beer temperature sensor into the mass of the beer. There is no heater connected, as I didn’t think it would be particularly necessary and I didn’t want to compromise the seal on the refrigerator to pass the AC power cord.  There is a separate room temperature sensor outside the fridge simply to log room temperature.

chilling wort

Below is the data showing the fermentation of this English Bitter style ale.  There is a lot of information there, but I find it clearly presented.  The orange line for refrigerator setpoint jumps around at the beginning as the PID algorithm works to find the right temperature to reach the target beer temperature, which I started at 66F but then reduced to 64F shortly thereafter.   You can see the fridge temp converge with beer temp near the end as fermentation slowed and stopped making significant heat. The beer temperature was rock solid the whole time within +/- 0.1F.  The beer tastes great and I’m very happy with the BrewPi.

special bitter brewpi

WiFi Beerbug Initial Review

Not long ago I received my third hardware example of the BeerBug, namely the current WiFi model.   Previously I had tested two previous incarnations that connected to the world using Bluetooth (see my blog posts tagged beerbug).  After seeing some good looking data from the new models, I took advantage of a reasonably priced upgrade process offered to Kickstarter backers to get the latest version.

Initial impressions were pretty good.  It has more LEDs than the earlier model to provide more information (though these could be documented better), and an integrated LiPo battery that so far has provided outstanding battery life compared to the older Bluetooth prototypes.  This BeerBug uses the Electric Imp platform to connect to a remote server using your home WiFi network, and from there data is accessible by smartphone apps and a web interface.  The hardware gets configured for home wifi by something they call blinkup where your smartphone flashes a coded signal onto a receiver on top of the device.  It is nice being able to see the data from anywhere you have internet connection, especially compared to the older version which required a windows device in bluetooth range.

I’d made a simple PVC holder to allow the “torpedo” weight to hang in sanitizing solution or water without occupying a fermentor, and used this to check the performance of the device.  Here the optional temperature sensor dangles alongside.

beerbug test rig

The software is not fully developed yet, though I thought it was in better shape that the earlier versions I had spent many hours trying to get working, exchanging dozens of emails with the ParasitX crew.  This time I was stymied trying to get the Android app to tare (i.e., calibrated to 1.000 specific gravity in water), receiving a message saying “did not receive a response from the imp servers.”  I thought I had a network firewall issue which led me down a fruitless path of trying to reconfigure my router and DSL modem.  Eventually I installed the iOS app and got the thing tared.  Even later I found that there is the ability to tare from the web interface, though this option was difficult to see.

I haven’t tested it in brewing yet, but here are some results from testing in water as I have done before, to check for drift, accuracy, precision, etc.   The very first run, below, had pretty quick drift up to about 1.005 in the first day or two but after that was steady with small variations of about +/- 0.002  specific gravity units.

beerbug initial trial

On around August 28 I tared it to re-zero at 1.000.  Instead of a vertical line in the chart as might be expected, there is at least one intermediate data point going down to after the completion of the tare, which is strange (see below chart).  I wonder if this is some sort of smoothing algorithm.  After having looked at some of the raw data from the bluetooth devices, I don’t miss seeing it, though the scientist in me is a bit put off  seeing a data point (as opposed to an interpolated line) where there should be none.

beerbug wifi longer test

Anyway, once I got the device set up initially it seemed to be working quite well overall with better consistency and usability than the bluetooth prototypes.  Supposedly the WiFi will connect from inside a refrigerator.  I look forward to using it with a beer.