Going solar

Firewood is sunlight converted into chemical energy. This wheelbarrow full + solar heat collectors (seen in the background in the last image) produce warm water+heating for one week in this record cold fall weather.

Coming Soon… varikonniemi will be 100% solar powered and off the grid at some point in the future! Stay tuned for full project post.

CO2 harvesting airlock

Also known as: CO2 harvester, cold-crash guardian.

Every homebrewer faces the problem of how to prevent oxidation. An airlock is almost universally used for this purpose, and it works fine as long as the temperature does not drop and the air pressure does not increase after carbon dioxide production has stopped. Otherwise air will be sucked/pushed into the carboy, causing oxidation and possible contamination. During cold crashing this is a problem.

And yet no solution is universally available in the homebrewing stores. Some commercial solutions exist and can be ordered online, but they are overcomplicated and overpriced, especially with international shipping. So i decided to make one myself, from parts you might very well have lying around if you are a homebrewer.


  • 3-piece airlock
  • Bag-in-box (BIB) bag
  • Hot glue
  • DIY

    Take the airlock and cut the foot off. Take the bag’s tap and remove the mechanism. Cut the wide top part of the tap body flat and then glue the air lock against the cut surface. The dispensing nozzle of the tap fits standard airlock hole size and makes a reliable seal. You may need to trim the bottom part of the tap’s collar to prevent it from hitting the bung/lid. The size of the bag should be chosen according to the size of the carboy. A 5 liter bag seems to work well with the 27 liter fermonster.

    Say hello to Twitter and Snapchat

    After replacing the mechanical timer from my previous attempt with a digital one capable of 1s timer resolution i was able to hatch 2/6 eggs with the timer set to turn the eggs for one minute every other hour.

    Say HELLO to Twitter and Snapchat:

    Here are my expenses so far:

    2x 6 eggs 3e (Lidl luomu, Smarket luomu | failed attempts)
    6 eggs 1.5e (Lidl luomu)
    drink&feed stations 10e (hautomakone.fi | includes p&p)
    food 19e (punaheltta paras poikanen | 30kg, it will take years to run out)

    Fully Automatic Egg Incubator

    This project combines my food warmer/heat plate and thermostat projects with an egg turning machine to make a fully automatic egg incubator. (yes, eggs must be turned several times per day during incubation!)

    The egg turning machine:

    Two plates of plywood. One as the body, the other as the turning plate. The turning plate is mounted using a normal bolt, spacers and lock nut. The plate turning motor is a repurposed paper feed motor from a 80:s printer. It has an integrated gearbox which makes the output rotation sufficiently slow when combined with the gearing ratio of the driving belt.

    The food warmer, thermostat and the egg turner combined into a fully automatic egg incubator. A glass container filled with water keeps the air humidity at ~55%.

    The thermostat is set to start heating at 36.5 degrees and stop at 38.5. The recommended temperature range for chicken eggs is 36,1 – 38,9.

    The egg turner is controlled by a wall timer set at 8x 15min turning per day. The 15min duration is a limitation of the timer i have, they only need to be turned once.

    The 6 organic eggs are from the local grocery store. Organic means among other things that there are some roosters in the pack, so the eggs may be fertilized 😮

    Food warmer/heat plate build

    This is a cooler that lost it’s lid close to a decade ago. Today it got a new life as the housing for a food warmer/heat plate. At the bottom is a thin steel foil to shield the styrofoam from the heat, and right under where the the heating element comes is an additional wrinkled aluminum foil. Both are mounted using aluminum tape.

    This is the heat plate. It uses a standard 25W e14 incandescent bulb for heating. Additionally, if the 5V DC power supply is plugged to the fan, the heat plate turns into a convection style food warmer. It would have been easier to use a small 230V AC fan, but i worked with what was available.

    This is the finished build in action. A storage box’s lid had to replace the lost original. To increase the energy efficiency (and temperature) it should be upgraded to something insulating, but sadly most insulating materials are not transparent.

    Electronic Live Mouse Trap

    This is a live mouse trap i decided to make when all local shops only carried regular mouse traps. With a little bit of luck my cat will get some new toys soon 🙂

    All used parts are random leftovers from other projects or from the trash. The heart of this project is a IR sensor with on/off logic, salvaged from a VCR.

    The power supply is a small wall mounted transformer with 8V AC output. Voltage doubling rectification is used to jump the voltage to ~20V DC. A capacitor is used to store charge for the solenoid. I have no specs on the solenoid but it seems to be working well in this configuration when using over 18V. 12V is enough if the door bolts are not added for extra weight.

    When the trap door falls a microswitch cuts the power from the IR receiver&solenoid and switches it over to a PC speaker to alert of the catch. Once fully closed, the door becomes mechanically locked and can only be opened by manually operating the solenoid.

    cheap thermostat project

    In this project a cheap (less than 4 euros inlc. p&p) Chinese 12V thermostat controller is built into a thermostat device which turns on/off the power to a normal 230V EU mains or 12V DC.

    The thermostat controller has adjustable on and off points, and display of the current temperature.

    A small 12 V transformer was chosen as the power supply method. After bridge rectification the voltage is regulated down to 12V. Both the input and the output of the regulator is filtered making it almost over engineered. The power supply is soldered on top of the DC capacitor:

    Under full load (relay on) the DC rail voltage is 14V with <1V ripple. This leaves a near-ideal 2V for regulation:

    Transformer output:

    Circuit diagram:

    Completed thermostat:

    Solar powered ventilation for greenhouse

    Last summer it became apparent that the greenhouse would get too hot on sunny and calm days even with the door and the automatic ventilation hatches open. Something had to be done. Solar powered ventilation is the answer! I decided to make a KISS system and use a laminated 10W solar panel to power two 120mm 12V computer fans. Just make sure the panel won’t be able to produce more power than the fans can handle, then there will be no need for any fancy controllers or anything. Solar panel -> fan(s).

    It was only necessary to cut a 120×240 hole in the wall, then drill four 4mm holes for bolting the fans to the wall because the fans are joined together.

    The bottom two screws additionally have 3mm threads attached at 90 degree angle to the fans. These are used to fasten a perforated sheet to the fans. The three acrylic pieces stand on the perforated sheet.

    The top two screws additionally have a splash guard attached. The splash guard also splits the airflow. The solar panel and the acrylic pieces are fastened using silicone. The thermostat is connected in series with the solar panel and the fans so it won’t ventilate if the temperature is under 29.

    Birch sap harvesting

    Birch sap has various medicinal and cosmetic benefits, and it is easily collected without damaging the trees. The sap starts to flow once the ground is not frozen any more. Once the leaves have developed the taste changes and the sweetness disappears.

    *Find a clean hose and measure the diameter.
    *Drill a hole of measured size in the cap of a suitable container.
    *Drill a hole of measured size in a healthy looking birch, then connect the hose.

    I did a test comparing 8mm and 12mm collection hoses. The thinner is better because it does not let air inside the hose which makes the hole dry up faster.

    Once collected, the sap is immediately ready to drink! If stored, run it through a tea sieve first to remove any debris.

    Birch sap will keep good in a refrigerator for 2-3 days. Alternatively it can be boiled and put in sterile bottles for longer term storage, but this changes the composition and taste. I prefer to freeze the sap for storage because it does not alter it in any way. To prevent nasty surprises in the freezer the bottles should not be filled completely full, and the air should be squeezed out before closing the cap.

    “one dL per day to keep the doctor away”

    firewood silo

    I find using firewood very enjoyable, it is an energy-dense and environmentally friendly fuel. Felling trees is fast compared to how much wood you get. Splitting the wood is quick and easy using a (vertical) hydraulic splitter.

    But finally comes the stacking phase, which i find annoying, especially for small (33cm) wood. This project is about eliminating the stacking phase by building a firewood silo where it is easy to throw the wood directly from the splitter’s work table.

    My plan involves building it using steel wire fence and as many repurposed parts as possible.

    dog fence, ~7.5m
    2x FIN & random pallet
    2×4 wood, 2 x 2.2m
    2×8 wood, 2.2m
    wood board (to repair broken pallets), 11m
    wood nails
    steel band
    roof nails

    I started the project by researching what type of steel wire fence to use. The most common type available is dog fence, but the standard model has too large grid size to make it sturdy and to stop the smaller woods from getting lodged. After looking around i found an independent importer who had a model available with large enough wire thickness (2.5mm) and small enough grid size (5x10cm).

    Then i got my hands on some 20 year old FIN and random pallets, so i decided to build the silo using them as a base. FIN pallets are 1×1.2m and the random are 1.2×1.2m. This resulted in the silo being an ellipse with the diameters 2.4×2.2m, and a volume of 8.3m^3.

    I flattened the ground and made 9 support spots for the pallet’s corners and made a simple support structures on top of them using two 2×4:s at the edges and a 2×8 in the middle. Then i repaired the pallets using board and made sure there are no holes big enough for firewood to fall through, keeping in mind to leave enough gaps for air to circulate.

    Next i placed the fence on the pallets, cut it to length, and hammered it in place using roofing nails and brackets made from steel band. Then i cut the door out and bent the remaining wire stubs to act as a hinge:

    The silo without door frames:

    To finalize the project i built frames for the door. For this i needed:

    10m of wood board
    steel band
    torx screws

    I used the screws to sandwich the fence between two pieces of wood. The door frame helps keeping the silo’s form intact as the wood exerts radial pressure on the walls. The upper 3 and lower 2 wire rings are connected so they won’t stretch, but where the door is cut the stretching force must be connected through the door frame or the silo will bulge.

    For the lower horizontal support i used two sandwiched boards plus a third one to connect them to the vertical boards, but at the top i used the steel band instead of a third board to make it more slim.

    The finished silo filled with 8.3m^3 of small firewood:

    Once the snow has melted and the ground thawed i will update this post with how i ended up keeping ground moisture&plants away.