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.

Interesting Bike Light Failure Mode

I saw the bicycle light of Mrs. Nerdly Endeavours flashing brightly while the bike was parked outside.  Thinking the light must have been left on, I went to turn it off but could not, though strangely enough by pushing the button enough the light would switch between flashing and constant beam modes.

After opening it up I saw that some corrosion around the button and figured the button was trashed.   I was getting ready to scrap it and checked the battery voltages to see if the batteries were worth saving.  They were all incredibly low, around 1.0 volts instead of 1.5.  It amazed me that the light would still turn on.  I decided to try new batteries and incredibly the switch started working.  I guess the draw of having the LEDs on managed to disable the circuit that handles turning the thing off.  Really weird that low battery voltage would make it so the light won’t turn off.

Quasi-high-output USB iPad charger from 12V with extension cable

I was disappointed in the performance of the “high output” dual USB car chargers I found that claimed a total of 4.2 Amps to charge two iPads but in fact could not provide that much current to even one device (failing to keep the iPad charge level from dropping while in use, despite getting an indication showing iPad charging).  Also, I wanted the works on longer cable to get things out of the way, while providing an additional 12v cigarette lighter socket for other uses.

A box with two high-output USB charging ports and a 12V socket was planned. The Murata 78SR-5/2-C seemed encouraging, promising 10 Watts at 5V output.  I set up a voltage divider as described by Ladyada to supply voltage to the USB data lines and encourage the iPad to draw more current,  but never managed to get more than about 0.9 A charging current:

nine hundred milliamps

In place of the iPad I tried an appropriate resistor rated for high power and found that the Murata could indeed put out two amps.  I tried various combinations of resistors to get different voltages on the data lines but never managed to get the iPad to draw even a full amp.  Oh well…  I moved the project from breadboard to protoboard and soldered it up, and cased it up with a Hammond extruded aluminum enclosure I had around.  Here’s a photo in a mirror showing the back with the 12V receptacle and power input line.


Kegerator Draft Tower Cooler to Avoid Initial Foam

I’m not alone in noting that, especially in summer, the first recent pour of homebrew tends to be foamy at first.  Part of the problem is that the beer in the draft tower cools down so that the CO2 in it becomes less soluble and tends to come out immediately. Today I set up a fan to blow cool air into the draft tower to try keep the beer in the draft tower cooler.

I used a fan from a dead old Mac Mini and a 5V power supply from a Ye Olde Palm Treo, soldering a 2.1mm barrel plug and socket to make it dis-connectable.

soldered fan and power supply

The fan is rated for 12V and the power supply is 5.2V.  I tried a higher voltage power supply and it did blow a lot more air, but subjectively the fan blew hard enough on the lower voltage supply, and it was definitely quieter.

I was able to run the power cord out through the drain port at the bottom of the fridge as seen here.


Here’s another shot of the installed fan with both kegs in the fridge.

installed 2

I used safety wire hold it in place.

Another BeerBug, Another Review

The BeerBug folks were kind enough to send me a replacement BeerBug (with a green LED instead of blue) in view of the problems I had with my early model.

I happened to have a beer fermenting so I tried it right away, but had some issues likely related to the line holding the torpedo weight being too long so that the weight partially rested on the fermentor.  And the beer was about done fermenting.

After shortening the line, I tried in again in a carboy of water to make sure things were sorted.

3g allon carboy

Normally the BeerBug is supposed to go to sleep after not talking to the app after a while, but in this first trial it never slept: the LED didn’t go to more the more dim flashing that indicates the low-power sleep mode, and the battery didn’t last very long.  Turns out you can soft-reset it by pulling the battery for a moment (it saves your data through this), but I didn’t do that this time.

Another trial of leaving it in water (starting with a new battery) for a while worked out much better:

new tare test

There is some drifting with the mild temperature fluctuations, but if you look at the scale you will see it is only about 0.04 gravity points.  The spike in mid-morning of May 12 is when I squired a little StarSan down the snout of the BeerBug just to see what sort of impact it would have.  Not too bad.  Overall this BeerBug seems pretty stable and definitely much better than the last one I had.

I look forward to trying it in a fermentation.

Repairing LED bike light

Mrs. Nerdly Endeavours had a LED bicycle tail lamp that had stopped working, even with fresh batteries.   It looked very simple so I opened it up to check it out.

Bike light

The LEDs are mounted on a circuit board that had contacts on the back for the on/off button and the spring clips to provide power from the batteries.

I didn’t take a “before” picture, but the contacts for the battery clips were kind of corroded.  I glooped some solder on them to see if that would help.

light circuit with solder

The arrow shows the new solder.  It didn’t stick to the entire contact area on the PCB, but it worked well enough to get the light shining again.

BeerBug Review

UPDATE: a newer BeerBug unit seems to have resolved these problems – see Another BeerBug, Another Review.

SECOND UPDATE:  Further test results reported here

THIRD UPDATE: the currently most recent fermentation trial here.  For all my BeerBug stuff, check my posts tagged BeerBug

To follow up my first impressions, here are my experiences after using the BeerBug hydrometer to measure the gravity of a batch of beer as it brewed.  As one of the first recipients of the device, I understood that there might be some snags, and so far the people at BeerBug have been very responsive in answering questions and the like.  For example, several of the issues I had were resolved by new Windows software.  Despite this, I found that my BeerBug is not (yet) usable for its intended purpose of measuring gravity during fermentation.

The beer I’d planned was a weizen. After letting the torpedo stabilize in water for a couple of hours while I finished the brew, I put it in the wort which was intentionally under-pitched.  The first few hours showed what seemed to be a vigorous fermentation with a quick drop in gravity, but there was actually no airlock activity.

Incredible fermentation

This was my first encounter with a wicked tendency of the BeerBug to drift.  Shortly after this, the battery died: turns out the BeerBug has a built-in memory so it’s better to leave it disconnected from the Bluetooth connection to the PC which will spare the battery and also allow the on-board software to average the collected data (over a user-selected period of time, recommended as 10 minutes) while discarding any odd outlying points.  The data was also preserved while swapping the battery.

With the new battery the BeerBug seemed to work OK for a few days.  The weather was such that the air temperature in the basement varied considerably between day and night, but the beer in the 10 gallon fermenter held a relatively stable temperature.  There’s not yet an immersed thermometer and as a result, it seemed that the temperature compensation of the BeerBug over-corrected in calculating the specific gravity, as seen in the beginning of the below data with diurnal swings.

the beginning of the end

The chart immediately above begins at a time near the end of fermentation with the BeerBug SG matching closely with that determined by a conventional hydrometer.  But a downward drift began that had the SG at times below 1.000, well below the actual beer which finished at 1.011.  Then the depicted gravity started drifting upward substantially.

Around the time the above chart ends, I bottled the beer and put the BeerBug in water to see what it would read.

Then things got really weird:

drifting and oscillating

The BeerBug went from the fermenting beer into water at around the time of the big spikes in the above chart.  The upward drift continued and then some really strange oscillations began as well.  I have no idea what caused this.

Here’s a photo of the “guts” of the BeerBug after I opened it up so see if some crud from the fermentation might be causing some problems.  There was a little yeast but it didn’t seem like enough to produce the weird results.  The oscillations happened even after I cleaned up the little bit of material in this photo.

bug guts

In summary, the performance of the device has been very erratic to the extent it’s not really useful for me right now.  Hopefully this can be fixed in software, though so far the cause of the drift and oscillations remains obscure.

Switches on hot air popper coffee roaster

The Poplite popcorn popper I’ve been using as a coffee roaster lacked even a simple power switch.  I ordered a couple of suitably-rated toggle switches and wired them in to control the power to the whole shebang as well as to switch off the heater while allowing the fan to keep blowing.  This should (1) allow for cooling of the beans in situ and (2) help cool the device between batches to prevent the thermal cut-out from kicking in.

The wiring inside the popper is really simple (check out the diode bridge around the DC blower motor) and I managed to wire the switches correctly by just eyeballing the scene.  Looking forward to using it.  By the way the chimney extension I made out of sheet metal works nicely.

Audio switch for airplane passenger

Mrs. Nerdly Endeavours likes to fly with me in the airplane, but she gets annoyed at the radio transmissions I have to listen to from air traffic control.  So I made an inline switch to block the incoming audio to her headset – she can still listen to her tunes and talk at me, but won’t hear ATC on the comm radios or (unfortunately) anything I try to tell her over the intercom.

It’s pretty simple inside – the rocker switch cuts out the signal from the tip of the phono plug to the tip connection on the jack.  I picked a switch that had a guard available to help reduce inadvertent actuation.  The headset plugs into the box and the box plugs into the airplane where the headset normally goes.

The microphone of the headset remains connected as normal, so the passenger can still talk to the pilot over the intercom.  This can be a problem because they can’t hear the communication radio so they might talk over an important transmission.

Despite the downsides, we are pleased with the switch box and take it on all our longer flights.