Air Compressor From Fridge Parts Gets An Upgrade

Air compressors are often loud, raucous machines – but they don’t have to be. [Eric Strebel] built a remarkably quiet compressor using parts salvaged from an old fridge. After several years of use, it was due for an upgrade (Youtube link, embedded below}.

While performance of the original setup was good, [Eric] desired a compressor with more capacity for his resin casting activities. A 15 gallon air tank was sourced from a damaged Craftsman brand compressor, and pressed into service. The build involved plenty of sheet metal work to mount the various components, as well as an upgrade to the pressure regulator.

During the refit, [Eric] takes the time to answer questions from the audience about his original build. He notes that the fridge compressor has worked well without using any noticeable amount of oil, and that there was a problem with water build up in the original tank which has been solved in the new rig.

It’s a great example of building your own tools, which can provide years of service if done right. Check out our write up on [Eric]’s first build, or his work on photogrammetry. Video after the break.

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Build Your Own Freezer With Thermoelectric Coolers

Freezers are highly useful devices. You can preserve food, stop a dead animal from stinking out your apartment, and keep your vodka at the optimal drinking temperature. Of course, most of us bought ours from the local whitegoods store, but [Tech Ingredients] set out to build his own (YouTube, embedded below).

Unlike your freezer at home, this build doesn’t use the typical heat pump and refrigeration cycle with a compressor and expansion valve and so on. Instead, this freezer uses thermoelectric devices to pump heat, in combination with a glycol cooling circuit and fan-cooled radiators.

It’s not the most efficient or practical way to build a freezer, but it is functional and the device demonstrably works, making ice cubes over the course of a few hours. Performance can be further improved by moving the radiator assembly outdoors to make the most of the low ambient temperatures.

[Tech Ingredients] has further plans to experiment with a dessicant-based refrigeration system, and reports that initial results are promising. We’re eager to see how that goes; we’re fans of any rig that can cool a beer down in no time flat. Video after the break.

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Hacked Vacuum Chamber Won’t Suck a Hole in Your Budget

There’s nothing like a true hack, where something useful is concocted from bits of scrap and bargain store finds. Builds like these are much more than the sum of their parts, especially when they result in a useful tool, like this DIY vacuum chamber that’s good for all sorts of jobs.

Everything [Black Beard Projects] used to accomplish this build is readily available almost everywhere in the world, although we have to note that appliance recycling efforts and refrigerant recovery programs have made it somewhat harder to lay hands on things like the old fridge compressor used here. The big steel cooking pot is an easy thrift store find, though, and while [Black Beard] used high-quality stainless fittings and valves to plumb the chamber, pretty much any cheap fittings will do.

The one sketchy area of the build is the plexiglass sheet used for the chamber top, which seems a little on the thin side to us. You can see it flexing in the video below as vacuum is pulled; it survived, but we can see it failing catastrophically at some point. We stand ready to be reassured in the comments. Still, it’s a tidy build with a few nice details, like wiring a switch into the old start capacitor box and using car door edge protector as a gasket on the chamber.

Fridge compressor hacks are standard fare, of course, being used to make everything from air compressors to two-stroke engines. Sometimes they’re even used to keep things cool too.

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Junkbox Freezer Alarm Keeps Steaks Safe

A fully stocked freezer can be a blessing, but it’s also a disaster waiting to happen. Depending on your tastes, there could be hundreds of dollars worth of food in there, and the only thing between it and the landfill is an uninterrupted supply of electricity. Keep the freezer in an out-of-the-way spot and your food is at even greater risk.

Mitigating that risk is the job of this junkbox power failure alarm. [Derek]’s freezer is in the garage, where GFCI outlets are mandated by code. We’ve covered circuit protection before, including GFCIs, and while they can save a life, they can also trip accidentally and cost you your steaks. [Derek] whipped up a simple alarm based on current flow to the freezer. A home-brew current transformer made from a split ferrite core and some magnet wire is the sensor, and a couple of op-amps and a 555 timer make up the detection and alarm part. And it’s all junk bin stuff — get a load of that Mallory Sonalert from 1983!

Granted, loss of power on a branch circuit is probably one of the less likely failure modes for a freezer, but the principles are generally applicable and worth knowing. And hats off to [Derek] for eschewing the microcontroller and rolling this old school. Not that there’s anything wrong with IoT fridge and freezer alarms.

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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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Fridge Parts Make Air Compressor That’s Easy on the Ears

Compressed air is great to have around the shop. The trouble is, most affordable compressors are somewhere between “wake the dead” and “the reason Pete Townshend is deaf” on the decibel scale. But with a little ingenuity and a willingness to compromise on performance, you might find this ultra-quiet, ultra-cheap air compressor a welcome way to keep the peace in your shop.

Yes, this compressor under-performs even a Harbor Freight pancake compressor which can be had for $60 and is ready to work right out of the box. In fact, [Eric Strebel]’s design sort of requires you to buy an air tank, and the easiest way to do that might be just to buy the compressor in the first place. But the off the shelf unit won’t run as quietly as this one does, what with a refrigerator compressor swapped in for the original motor and pump. There’s also a silencer on the input side, fashioned from a shaving cream can and some metal wool. The video below shows the build, and the results are impressive, at least from a noise perspective. Whether it suits your shop depends on your application – it certainly won’t run an impact wrench, but it’ll blow chips off your mill or dust out of your computer.

Fridge compressors are a natural starting point for air compressor builds, like this fire extinguisher based design, or this high-pressure tandem compressor. But if you need high flow and don’t care about the racket, try ganging four HF compressors in parallel.

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There’s a Pi In Mike’s Fridge

How often have you stood in the supermarket wondering about the inventory level in the fridge at home? [Mike] asked himself this question one time too often and so he decided to install a webcam in his fridge along with a Raspberry Pi and a light sensor to take a picture every time the fridge is opened — uploading it to a webserver for easy remote access.

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