Making Carbonated Mineral Water

I really like the refreshing taste of San Pellegrino, but dislike that this water is bottled in Europe, shipped over water and delivered to me in Milwaukee, where we also have water.  San Pellegrino costs about $1.75 per liter, and comes in recyclable bottles. The homemade version I’ve been making for the last four months costs less than one penny per liter, and is made in my kitchen in reusable bottles.   The cost of the equipment was less than $150, which paid for itself after I’d carbonated my first 100 liters of water.

The equipment required is relatively simple: An aluminum tank that contains 5Lbs of CO2, a gas regulator, a hose ending with a locking Schrader air chuck, a plastic bottle, a bottle cap with a Schrader valve stem mounted in it and two hose clamps.  All of these items are visible in the photos below.

Carbonation Caps With Fittings

The aluminum tank and gas regulator are available locally at restaurant or homebrew supply stores, or online from places like or  Prices at these latter two places are $85 – $100 for the pair.  I filled the CO2 tank for $9 at a local beer retailer.  I purchased the locking chrome plated air chuck, the stainless steel hose barb connected to it, the hose clamps, and the steel wire reinforced hose from a local hardware store for $15.  The Schrader valve stems were purchased from a local auto parts store – they are fully chrome plated, and are sold as replacement car tire valve stems for $2 each.

I initially used standard industrial air hose fittings instead of Schrader valves, but ran into several problems.  Only one side of this type of fitting seals when the mating fittings are disconnected.  This means that after a liter is carbonated and the hose is detached from the plastic bottle, either all the CO2 in the hose leaks out, or some of the CO2 leaks out of the bottle.  Also, inexpensive industrial air fittings are either made of steel or bronze and begin to corrode due to exposure to the carbonic acid formed when the water is carbonated.  Chrome plated Schrader valves have neither of these problems, and are even less expensive than industrial air fittings.

The carbonation process is also simple.  I fill a plastic San Pellegrino bottle 80% to 85% full of Brita filtered water chilled to ~36 degrees (standard refrigerator temperature), I squeeze all the air out of the bottle and tighten the plastic cap with the Schrader valve onto it.  I fully open the CO2 tank valve, set the gas regulator valve to 55 PSI (typical commercial waters are carbonated to about 20 PSI), squeeze the locking Schrader air chuck, and lock it onto the bottle.  CO2 immediately begins to flow, and inflates the bottle instantly.  An audible hiss continues as the CO2 pressurizes the bottle, which I shake vigorously for 20 to 25 seconds, after which time the CO2 hiss has stopped.  The hose is then disconnected from the bottle, and the water is carbonated!

All these details are important to successful carbonation.  The empty space in the bottle (the 15% to 20% of the bottle that doesn’t contain water) is critical to allowing the CO2 to get and stay in suspension.  The amount of CO2 that is soluble in water increases with colder temperatures.  Squeezing out all the air allows for more CO2 to fit in the bottle.  Shaking the bottle increases the rate at which the CO2 dissolves in the water.  All of these factors make for more fizzy water (which is the goal, right?)

The taste of San Pellegrino can be more accurately replicated with the addition of minerals.  With the addition of 1/8 tsp of Magnesium sulfate (Epsom salts) and 1/8 tsp of calcium chloride, one achieves the 210mg/L of Calcium and 60mg/L of Magnesium that San Pellegrino has!  Both of these minerals are wine/beer brewing additives, and can be purchased from local homebrew supply stores.  Check here for more mineral additive possibilities, and the book “The Good Water Guide” for the mineral composition of most commercial waters on Earth.  I find that carbonating to 55 PSI rather than a more reasonable 20 to 25 PSI makes for so much more joy that I (and my kidneys) don’t miss the extra minerals.

If you want to make this setup at home, please follow these safety guidelines.  There are several which are very important, as a gas cylinder is somewhat dangerous, as its internal pressure is between 700 to 800 PSI, depending on temperature.   Carrying the cylinder by its valve is a bad idea.  The tank should be secured at all times so it doesn’t tip over and damage the valve.  When it is transported, it should always be upright and it shouldn’t be left in a car sitting in the sun, as the internal pressure will increase hundreds of PSI.  The regulator you purchase should have a pressure safety valve which releases at ~60 PSI to vent excess pressure and prevent your plastic bottle from exploding.  Similarly, your hose should be rated for higher than the pressure you intend to carbonate to.  You should never carbonate in glass bottles.

I measured the pH of my 55 PSI carbonated water, and found it to be 4.6, whereas the pH of Coke is a much more acidic 3.2, as shown below.  The pH of my water prior to carbonation was a perfectly neutral 7.0.

Basic and Premium StrobeTV

Do you ever want to watch a movie at home, but can’t decide between your favorite two?  Maybe your favorite TV show is about to start, but you’re still watching a film on DVD?  Perhaps you and a friend can’t agree on which film to watch? Well, you need not fret if you’re an early adopter of StrobeTV – a new device that enables the viewing of TWO films simultaneously on a single television by simply alternating between them!  The basic version features two knobs for fine-tuning your experience.  One sets “impatience,” which is how long you’ll view and listen to one film before switching to the second film.  This can be set from once every10 seconds and mere fractions of a second! The second knob controls “preference” or the relative amount of time spent watching the first or second film – perhaps you want to view the first film 60% of the time, and the second 40%.  Or, might it be 25% first and 75% second?

If you’re the proud owner of the Premium StrobeTV, a world of customization is achievable using the eight three position switches and two knobs.  The upper row of switches configures the experience you’ll enjoy for an amount of time set by the upper knob.  When this time expires, your experience is set by the lower row of switches for the amount of time selected by the lower knob.  Naturally, the process repeats, endlessly alternating between your two chosen forms of entertainment – be that TV, DVD, Netflix, gaming consoles, etc.  Perhaps you feel you’ll miss out on important action while you’re watching one film? Premium StrobeTV allows you to listen to the left and right audio channels of the second film, while you view the image from the first film!  Maybe you’re more comfortable reserving the left speaker for playing the left channel audio for the film you’re not currently viewing?  Or maybe the audio alternates? With StrobeTV, the possibilities are virtually endless.  Premium StrobeTV has an enhanced switching range, from once per 15 seconds to over forty times per second, ensuring you won’t miss a single detail!

Premium StrobeTV features an ingenious 2 meter long  cable that allows the controls to be at your fingertips, while the wiring remains hidden away.  Note that Premium StrobeTV, like its more economical sibling, allows for the switching of four signals: right audio, composite video, left audio, and a forth signal of your choice!


Redwood Audio Amplifier

A few months ago I started collaborating with Jordan Waraksa on a project that is currently on display at the Haggerty Museum of Art, in a show running until the end of December.  He sculpted a pair of wooden acoustic horns called Bellaphone 5 & 6 out of walnut.  Each horn rests on a redwood base that houses a small speaker.  If you visit the Haggerty, you’ll hear the speakers playing songs by Jordan’s band, The Vitrolum Republic.  If you really love the Bellaphones and amplifier, know they are for sale.

I developed and built the electronics for the horn’s amplifier, whose chassis Jordan also sculpted from redwood.  Because the chassis is wood and has no vents (for aesthetics), electrical efficiency became a high priority in order to prevent overheating.  I chose to use a Maxim 98400A class D amplifier driven by a high efficiency switching 15V DC power supply.  I added a digital signal processing chip from Analog Devices to increase the bandwidth of the horn and smooth out its frequency response (i.e. to improve the audio fidelity).  Analog’s ADAU1701 is a remarkably powerful chip – it is more than capable of these tasks.  In addition, the 1701 prevents bass notes (frequencies below 100 Hz) from reaching the small speakers (which are incapable of reproducing these low notes), which would otherwise emanate from the horns as distortion.  Finally, the 1701 also adds a small amount of compression, which prevents distortion at the loudest output levels.   The 1701 is actually real-time programmable via a USB connection to a computer running Analog Device’s free SigmaStudio software.  It’s a tremendously user friendly GUI environment with drag and drop audio processing blocks.

Check out the inside of the amplifier as it was being assembled, prior to the addition of many ferrite beads which eliminate the audible noise from the three high efficiency switching power supplies:  One powering the amp, one powering the DSP board, and one continuously charging a Motorola Cliq XT handset playing songs from the Vitrolum Republic.

Here are two more close ups, one of the amplifier:

And one of Bellaphone five and six:


I’ve recently made several audio synthesizer / noise generating boxes.  The most recent is the Cacophonator, whose circuit description and board layout are easy to find on the web.  Thanks to Adam for showing me how to etch my own circuit boards – something I can now do quite easily at the Makerspace.  I modified the board layout, drawn in DipTrace, so I could add SIP sockets and pin headers to tidy up the inside of the project box.  The sockets also allow the board to be easily removed, despite the 20 wires running between the board and other components inside the project box.  The  photos below were taken before I modified the circuit by adding a momentary power switch to slowly recharge the giant power supply capacitor if held for a few seconds.  I also added a LM317 adjustable voltage regulator so the power supply voltage can be reduced all the way down to 1 V DC and below.  The sonic complexity of this circuit is surprising considering its small part count, and lowering the power supply voltage further adds to the chaotic behavior of the cacophonator.  Careful inspection of the board will show additional components not associated with the original cacophonator, but are discussed on  These are used for inputting audio signals (music, for example), which come out the RCA jack quite cacophonated.


Makerspace Eight Speaker Super Surround Sound System

The day has finally arrived: The Makerspace Eight Speaker Super Surround Sound System (MESSSSS) is fully installed, wired and amplified.  This morning MESSSSS reproduced its first 8 channel audio piece, authored using adobe audition and played back by four android devices through four 1/8″ stereo cables feeding the bank of amplifiers.  More integration work remains to be completed (a dedicated computer with an 8 channel sound card plus a patch bay) but the MESSSSS is up and running!

Bay View Gallery Night is Friday, June 3rd at the Makerspace

Friday, June 3rd is Bay View Gallery Night: The Milwaukee Makerspace is hosting our own artists, and artists from Bay View Arts Guild to show their work. We have over 20 confirmed artists, plus two bands and more!  Stop by the Makerspace between 6pm and 10pm!

BVAG Participants:
Janet Falk / fiber
Karen Costello / jewelry – recycled stuff
Terry Nichash / photography
Ian Pritchard / photography
Donna Pogliano / jewelry
Cali Thomas / paintings
Anita Burgermeister – paintings
Stan Doty – wood carving
Erich Ebert – poetry & installation

MM Participants:
Brent Bublitz – sculpture
Jackie Steffen – illustrationsc
Kevin Bastyr – sound sculpture
Pete Prodoehl – drawing robots
Matt Neesley – sculpture
Amanda Endries – collage
Jason Gessner – interactive audio
Matt Gauger – interactive audio
Ross Oldenburg – interactive audio

Community Participants:
Dani Schmidt – Vase Sculpture
Bill Arthur – Painting
Lisa Sim – jewelry

We also have two bands playing: Makerspace’s own Ross Oldenburg in his band The Plane to Lisbon, followed by Steve Cohen.

Interested in Milwaukee Makerspace Membership or Information?

Curious about Milwaukee Makerspace Membership after attending our Open House on Saturday? Feel free to attend the weekly meeting held at our space at 3073 S. Chase Ave Building 34. The meeting starts every Tuesday evening at 7 P.M. and lasts about an hour. After the meeting all types of Making will be happening. The Milwaukee Makerspace is also open for prospective-member visits on Thursdays after 7pm on our weekly electronics night – its BYOEP (Bring your own electronics project). Please do stop by to meet the Makers! We hope to see you on an upcoming Tuesday or Thursday night!

Jacob’s Ladder

In about 30 minutes after the Makerspace meeting on Tuesday, Ross, Jason and I made a Jacob’s Ladder from an old neon light transformer that I brought in, a couple pieces of wood, and some TIG welding aluminum filler rod.

With 110 Volts at its input, the transformer put out 9000 Volts! The arc formed across the gap, but it wasn’t actually a high enough voltage to make the arc ascend the ladder. When I hooked the transformer through a Variac and turned the knob to 130 Volts, the arc began to ascend the ladder – but only a few inches. The obvious solution was to add more voltage, so I hooked another Variac in series with the first, turning this one to 140 Vac. With the output of the transformer a bit under 12000 Volts, the arc ascended over 2 feet up the ladder. Check out the video below showing the arc’s interaction with wood.

Rubens Flame-Tube

Last Saturday morning I spent 4 hours making a Rubens Tube at the Makerspace while the crew from Pumping Station: One was shooting footage for their documentary entitled The Rebirth of the Maker Movement. Here is the first lighting of the tube:
Milwaukee Makerspace: We play with fire
A Rubens Tube is a pretty flashy piece of physics demo gear that uses fire to show the acoustic standing wave pattern inside an organ-pipe like tube fitted with a loudspeaker at one end. The 48” long, 2.5” diameter tube is filled with propane, which escapes through a series of 50 0.043” diameter holes spaced by 0.9 inches all along the length of the tube. Once the tube is full of propane (with absolutely no air), the 50 propane jets are lit with a striker or match, and all 50 flames have an identical height of 2 or 3 inches. When sound is played though the speaker at one end of the tube, the flame height is modulated by the acoustic pressure from the speaker. When a single tone (sine wave) at a resonance frequency of the system is played though the speaker, the heights of the flames map out the sinusoidal shape along the length of the tube. Playing music with dynamics or signing through the speaker is especially dramatic. I need to spend a few more hours fitting the Rubens Tube with a speaker at the other end and adding an additional propane inlet.