Home Brew – CO2 Carbonation Chart

Use this chart to determine the ‘set and forget’ settings (temperature and pressure) to apply to your kegged beer to properly carbonate it with a CO2¬†pressure tank.¬†There are a couple of these around on the net, but usually limited to degrees fahrenheit and a few other annoyances for me, so I took a couple of minutes to put together mine own slightly more simplified version.

Carbonation Chart


Home Brew – Freezer to fermentation chamber conversion

For my home brew endeavors I had another problem to solve… a temperature controlled chamber for fermentation.

I had the following constraints/requirements:

1. Get it cold enough (10 – 15‚ĄÉ) for lager yeast. I live in a hot climate.
2. Large enough to allow my 30 litre fermenter (H:530mm,Dia:300mm) or my 6.5gal glass carboy (H:520mm, Dia:305mm) to fit.
3. Rather precise ¬†temperature accuracy¬†(~0.5‚ĄÉ)
4. Not cost “a lot”.

I decided that buying a suitably sized chest freezer and putting in a digital thermostat would be the way to go – Here’s what I bought:

1. Chest Freezer – Farfalla FCF-128A
– $299
– 128 litres
– External dimensions (W:750, H:780, D490)
– Available area for full-size fermenter (H:580, W: 382) (i.e. not including space above the “step”/”bump” inside the freezer due to the compressor)

2. Digital Thermostat – FOX1004

– $80
– Range 40.0 to 90.0‚ĄÉ
– 1 relay, 250 VAC 2A. Note: Not rated high enough to take full compressor load, hence the need for the contactor
– External dimensions (W:770, H:350, D:770)
– Input sensor diode(wire length : 3 metres)
– Input 230VAC 50/60Hz

3. Contactor – Schneider LC1K0901M

– $25
– TeSys K contactor
– 3P(3 NO) – AC-3 – <= 440 V 9 A
– 220…230 V AC coil

Now time to wire everything up.

Here is how I did it (click on the image to make it larger)

CircuitDiagram v0.2

The finished product


Note the thermometer probe is in the bowl filled with liquid – this will ensure a closer match to the actual beer temperature. Also, I put a battery powered (for now) fan in the chamber for circulation – need put in a better solution.


Home Brew – DIY Stir-plate

Inspired by one of my friends, I’ve decided to get into the world of home-brew beer. Of course I looked over all his gear and¬†immediately¬†got obsessed with the electronic components and how I could somehow automate things and connect things to the web… raspberry pi’s etc etc… but I did notice something much less ambitious, a¬†magnetic¬†stir plate, which is used for making the yeast starter in the home brew process.

Here is the finished product:

Components I used:

  1. Cigar Box – Had one around.
  2. AC-DC 12V Adapter (1.0A) – $10
  3. DC female input – $1
  4. Illuminated switch DC – $1.50
  5. Future Kit 804PWM based DC motor controller – $10
  6. Nice knob to attach to the potentiometer on the PWM controller – $1
  7. Standard DC Fan 80x80mm. 12V, 2.4W. Range 7-15V – $7
  8. Hard drive magnet – $4
  9. Stir bar(s) – $5 each
  10. General bits (wire, things to elevate the fan position)

Few things I learnt along the way:

  1. Don’t JUST use a¬†potentiometer, use PWM.¬†A common approach is to simply use a potentiometer between the power source and the fan. The main reason this is not effective is that standard DC fans need a rather ‘high’ minimum voltage to even rotate, in the case of mine, 7V. What this means is practice is that the majority of the potentiometer turn does nothing (I used 500 ohm, the smallest I could find), and that 7V was too fast to effectively bring the stirbar into a controlled spin. The better approach is to use PWM, in very simple terms this always provides full voltage, in this case 12V, but pulses it on and off very quickly to control the speed. What this means is that rotation of the potentiometer on the PWM controller gives you full control of fan speed. I was lazy and bought a pre-made PWM controller, if you’re more¬†adventurous¬†you could assemble a kit or built from schematics found all over the web, for example.
  2. Careful removing the hard drive magnet. I broke mine, fortunately it still works ok. Suggest you be very gentle and follow the instructions in this video.
  3. 2mm thick neodymium magnets are not enough. After I broke my hard drive magnetic I bought two 2mm thick circular magnetics, these were not strong enough in my case, would suggest around 4mm. I ended up using my broken hard drive magnets.
  4. Have the right tools.¬†In my¬†embarrassingly¬†many attempts to build this I did so without the right tools, which caused lots of frustration and shorted components. The tools I ended up buying made the entire stir-plate DIY more expensive than buying a generic one… but lessons aren’t free ūüôā and thats no fun. Some ‘tools’ I’d recommend are:
    • Stand/Holster for your soldering iron
    • Something to hold PCBs, wires etc to free your hands. For example.
    • Multimeter (mine one’s battery was flat the first attempt)
    • Test using a 9V battery rather than full 12V 1A DC source
    • Not a tool, but if you’re unexperienced like me… watch some YouTube videos about how to solder!