Listen To Your Fermentation To Monitor Its Progress

If you are a wine, beer, or cider maker, you’ll know the ritual of checking for fermentation. As the yeast does its work of turning sugar into alcohol, carbon dioxide bubbles froth on the surface of your developing brew, and if your fermentation container has an airlock, large bubbles pass through the water within it on a regular basis. Your ears become attuned to the regular “Plop… plop… plop” sound they make, and from their interval you can tell what stage you have reached.

[Chris] automated this listening for fermentation bubbles, placing a microphone next to his airlock and detecting amplitude spikes through two techniques: one using an FFT algorithm and the other a bandpass filter. Both techniques yielded similar graphs for fermentation activity over time.

He has a few ideas for improvement, but notes that his system is vulnerable to external noises. There is also an admission that using light to detect bubbles might be a more practical solution as we have shown you more than once with other projects, but as with so many projects on these pages, it is the joy of the tech as much as the practicality that matters.

Portable Stir-Fry Range

If you love a good stir-fry, you know that it can be a challenge to make on your stove at home. Engineer gourmet and Youtuber [Alex French Guy Cooking], in collaboration with [Make:], whipped up a portable range capable of making delectable stir-fry.

There are three major problems when it comes to cooking stir-fry: woks are typically unstable on normal burners, those burners don’t tend to heat from a center point out, and they usually aren’t hot enough. [Alex]’s 12,000BTU portable stove is great for regular applications, but doesn’t cut it when it comes to making an authentic stir-fry.

To focus the burner’s heat, he cut and bent a stainless steel baking ring into the shape of an exhaust nozzle — not unlike a jet engine — and lightly modified the range to accommodate the nozzle. He also added a larger baking ring with air flow holes for the wok to rest on. Two down, but there’s the issue of it not being hot enough.

So, why not use two butane canisters to double the output to 22,200 BTUs!

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Camp Kitchen Kit For Food On The Go!

Camping and road trips are a heck of a lot of fun, despite lacking many of the creature comforts that come from a house and its amenities. We’re all for fire-cooked meals, but sometimes, you want a cook-top and a sink to make cooking on the go a quick process. What if you could pack up a kitchen into a box and take it with you?

[pointblankjustice]  — opting for overkill — built this for his girlfriend instead of the requested box to simply store camping supplies. Glued and screwed plywood forms the frame, drawers, and lid which was then stained and painted to make for an appealing finish. A simple propane camp stove makes a worthy cook-top.

Obviously, one must include a kitchen sink, so a small bar sink and hose faucet are kept running with a cheap, 12V, 35psi pressure pump from Amazon. A little doughnut magnet keeps the faucet secured when not in use. Spent grey-water drains from a hose into a bucket or into a ditch (don’t worry — [pointblankjustice] uses biodegradable soap!).

As an added bonus, [pointblankjustice] has some under-cabinet lighting and accent lighting to keep things cooking late into the night, with power supplied by an extension cord going to their Jeep’s cigarette lighter outlet — plans to add a built-in battery are pending. There’s also a pair of USB ports to keep one’s phone charged and a bear-shaped bottle opener to keep the good times rolling!

The kit packs up nicely and fits snug in the rear of [pointblankjustice]’s Jeep with enough room for other supplies and a pair of dogs.

For longer hauls out into the wilderness, you might consider bringing a solar power supply unit that literally lasts for days.

[via /r/DIY]

A Cold Press Juicer For the Price of a Few Trips to Jamba Juice

Do you enjoy drinking juice but hate the cleanup after making it? Yeah, we do too. So does [Max Maker], which led to the design and birth of the $40 cold-press juicer. If you’ve been thinking about buying a juicer but the cost has been keeping you from pulling the trigger, you should definitely check it out. This build will save you some serious cash and looks relatively simple to replicate.

[Max] designed this juice press while keeping us common folk in mind who don’t have expensive tools in our humble garage or workshop. For example, to make the tray, we are shown how to perform the initial bends in the sheet of stainless steel using only some plywood and clamps. Then we’re shown how to bend the corners, and finally the ‘funnel’ part of the tray with just a few more basic tools – a bench vise, hammer, and pliers. No metal brake required!

The press is easy to use – wrap your fruit or vegetables in some cheesecloth, put it on the tray, and pump the handle of the jack. Clean-up (which has been a notorious pain-in-the-rear when it comes to commercial juicers) is quick and simple too – just rinse the tray!

Build video after the break.

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Cooking With The Awesome Power Of Plasma!

There is something special about food that has been cooked in a grill, barbecue, or broiler. The charred surface brings both flavour and texture to the food, that other cooking methods fail to emulate. Of course, should you come from a part of the world in which the locals steam their hamburgers those are fighting words, but for [Robots Everywhere] the prospect of a flaccid patty cooked in a microwave oven was too much.

His solution? Broil the microwaved meat in double-quick time, using a plasma arc generated with a high voltage supply. The patty is placed in a grounded metal frying pan, and the high voltage probe is run over each side with accompanying plasma and sparks to lend that essential grilled exterior.

The power supply is a fairly simple affair, if a little hair-raising. A simple push-pull MOSFET oscillator drives a pair of flyback transformers whose secondaries are connected in series. It’s not the most efficient way to generate high voltages with a flyback transformer – the key is in the word “flyback” – but it generates enough juice for the job in hand.

It’s hardly the safest cooking method, and we’d be worried about contamination from whatever metal the electrode is made from. But it’s entertaining to watch, as you’ll be able to see from the video below the break.

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The Internet of Rice Cookers

You’d be forgiven for thinking this was going to be an anti-IoT rant: who the heck needs an IoT rice cooker anyway? [Microentropie], that’s who. His rice cooker, like many of the cheapo models, terminates heating by detecting a temperature around 104° C, when all the water has boiled off. But that means the bottom of the rice is already dried out and starting to get crispy. (We love the crust! But this hack is not for us. This hack is for [Microentropie].)

So [Microentropie] added some relays, a temperature sensor, and an ESP8266 to his rice cooker, creating the Rice Cooker 2.0, or something. He tried a few complicated schemes but was unwilling to modify any of the essential safety features of the cooker. In the end [Microentropie] went with a simple time-controlled cooking cycle, combined with a keep-warm mode and of course, notification of all of this through WiFi.

There’s a lot of code making this simple device work. For instance, [Microentropie] often forgets to press the safety reset button, so the ESP polls for it, and the web interface has a big red field to notify him of this. [Microentropie] added a password-protected login to the rice cooker as well. Still, it probably shouldn’t be put on the big wide Internet. The cooker also randomizes URLs for firmware updates, presumably to prevent guests in his house from flashing new firmware to his rice cooker. There are even custom time and date classes, because you know you don’t want your rice cooker using inferior code infrastructure.

In short, this is an exercise in scratching a ton of personal itches, and we applaud that. Next up is replacing the relays with SSRs so that the power can be controlled with more finesse, adding a water pump for further automation, and onboard data logging. Overkill, you say? What part of “WiFi-enabled rice cooker” did you not understand?

Build Your Own In-Fridge Soda Fountain

Who doesn’t love an ice cold soda? Lots of people, probably. This one’s not for them. It’s for those of us that are tired of having to go through the arduous process of manually opening a bottle and pouring a drink. Wouldn’t it be cool if you could have your own soda fountain at home? [Kedar Nimbalkar] thought so, and built a soda fountain that you can install right inside a fridge.

The system is based around using small pumps marketed as “6V DC air pumps” on Amazon. [Kedar] uses an indirect method of pumping the soda in this project. It’s a sad fact that it’s hard to find a cheap pump that’s safe to use with fluids for human consumption, and on top of that, many types of pump out there aren’t self-priming. This means the pump needs to be charged with fluid to work, which can make changing empty bottles a real pain.

Instead of pumping the fluid directly, the pumps instead push air into the top of the sealed soda bottles, which forces soda out of another tube in the bottle. This means that the pumps themselves don’t have direct contact with the soda which is a great design when working with stuff you’re going to put in your body. Following on from this careful design, the tubing selected is food safe. Unfortunately, even though the pumps don’t directly touch the soda itself, it’s highly unlikely the pumps chosen (designed for aquariums) are genuinely food-safe themselves.

When you’re building a beer funnel setup for Australia Day/4th of July/Other, using all manner of industrial or agricultural fittings may be a relatively low risk, as it’s a one-off exposure. But if you’re building a system handling products for human ingestion that you’re using on a regular basis, you really do want to make sure that the parts you use aren’t slowly poisoning you. There’s many ways this can happen — parts may corrode or react with substances in the food, plastics may outgas, or there may be lubricants in the parts that have toxic compounds in them. Just look what can happen if you drink wine out of a gun barrel — and that was from a single exposure!

Overall it’s a cool project, and one that would be especially fun and educational to do with children. Young humans are well known for their predilection towards sugary beverages, and have minds ready to be filled with knowledge about pumps, safe food handling practices, and of course, electronics. We also like [Kedar]’s use of commonly available materials, like a plastic food container for the enclosure. The project would be a great starter on your way to building a more complicated cocktail-mixing barbot. Video after the break.

We know peristaltic pumps are the go-to for safe liquid pumping. Anyone know a hacker friendly way of pumping air while ensuring all parts of the system are food safe? The most creative solution we’ve seen is to use breast pumps but it wasn’t ideal. Let us know your own tricks in the comments!

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