The fermenting beer showing the bubble counter in place.
To allow me to keep an eye on the status of fermentation within the demijohns while they are fermenting I designed a fermentation bubble counter.
The purpose of this small electronic board it to count the bubbles rising the air lock in a demijohn, As long as all the brewing/fermentation parameters are similar when I brew the exact same beer I would expect the number of bubbles and rate of bubbles at a particular time during fermentation to be the same. So far this does seem to be the case.
At the very least it should give me an idea of when a stuck fermentation may be occurring and also help me to decide when fermentation is slowing/stopping and I should take a gravity reading.
The small stripboard showing the bubble count electronics
Closeup of the bubber counter positioned on the Air lock
The actual electronics used are quite simple, An infrared led is placed on the board at a location where it shines through the thin part of the airlock where bubbles must pass.
On the other side of the airlock is placed an infrared photo transistor which constantly detects the infrared passing through the water in the airlock.
The output from this photo transistor is then fed into a comparator IC so that a nice signal output is available.
When air passes through the airlock the infrared beam is deflected for a fraction of a second and the signal from the photo transistor drops. This then turns off the signal from the comparator. This output is then fed into the Pokeys57e board which counts the amount of these pulses.
The graph of the bubbles is always available on the android application. An example graph of a brew which has only just begun fermenting is shown here.
The heated and insulated fermenting enclosure
To allow me to control the temperature of the demijohns during fermentation I had to build an insulated enclosure.
So I didn’t have to use any space in the house for brewing this was constructed in the garage along with the brewery. Unfortunately during winter it gets very cold in here.
To allow me ferment while it is cold in winter I made the enclosure. It’s constructed by surrounding some of the storage shelves I use in the garage with sheets of wood covered with polystyrene for insulation.
At the bottom of the enclosure I’ve put a heating plant propagator, The propagator is made to keep the bottom of it at a stable 18 degrees C which is quite a good temperature for overall fermentation of the beer I’ve made.
So I can check the temperature within the enclosure I’ve also put a Dallas one wire temperature thermometer so I’ve always got an instant reading without having to open the enclosure.
The Empty Fermentation Enclosure
At the front I’ve put some clear perspex sheets so I can keep an eye on the fermentation within the demijohns throughout, I’ve also put some strips of insulation material between the perspex fronts and the sides to ensure it’s as insulated as possible.
In the future I may improve the temperature control during fermentation by turning off the heater under the control of my control system but for now it’s just left permanently on.
Fermentation enclosure with new tubular heater and fan
After running this setup for about a year I decided it needed a little upgrade to improve the heat being held in the enclosure, to this end I installed a new temperature controlled tubular heater. This now means I can have as much or as little heat in the enclosure as I want by just twiddling the little thermostat on the unit.
At the same time I installed a small circulation fan to try and reduce any cold or hot spots which might be found in the enclosure.