If you buy a used heat pump that was made in China and try to use it in Northern Europe, there are bound to be issues. If said heat pump ends up encased in a block of ice that renders it ineffective, you’ve got two choices: give up and buy a proper heater, or hack a new ice-busting brain board into the heat pump and get back to life.
[Evalds] chose the latter course, obviously, and in the process he gives us a pretty good look at how heat pumps work and how to overcome their deficiencies. In [Evalds]’ Latvia, winters can be both cold and humid, which can worsen an inherent problem with air-coupled heat pumps: they tend to ice up. As the outside coil is cooled to pick up as much heat as possible from the outside air, water vapor condenses out on the coils and freezes. Most heat pumps account for this by occasionally running in reverse, heating the outdoor coils to clear the ice buildup. [Evalds]’ had nothing more than a simple timer to kick off the defrost cycle, and it wasn’t keeping up with the Latvian winter. An Arduino replaced the OEM controller, and wired up to temperature sensors and an IR sensor that watches for ice buildup on the lower part of the coil, the heat pump is now much better behaved.
Of course it wasn’t as smooth as all that — [Evalds] has some hoops to jump through, including EMI problems and a dodgy Arduino clone. But he stuck with it and brought the heat pump back online, likely at far less expense than HVAC techs would charge for a service call.
Building a software defined radio (SDR) involves many trades offs. But one of the most fundamental is should you use an FPGA or a CPU to do the processing. Of course, if you are piping data to a PC, the answer is probably a CPU. But if you are doing the whole system, it is a vexing choice. The FPGA can handle lots of data all at one time but is somewhat more difficult to develop and modify. CPUs using software are flexible–especially for coding user interfaces, networking connections, and the like) but don’t always have enough horsepower to cope with signal processing tasks (and, yes, it depends on the CPU).
[Eric Brombaugh] sidestepped that trade off. He used a board with both an ARM processor and an ICE FPGA at the heart of his SDR design. He uses three custom boards: one is the CPU/FPGA board, another is a 10-bit converter that can sample at 40 MSPS (sufficient to decode to 20 MHz), and an I2S DAC to produce audio. Each board has its own page linked from the main project.
When life gives you lemons, you make lemonade. When life gives you freezing cold temperatures and a yard full of snow, you make binary clocks out of ice. At least that’s what [Dennis] does, anyway.
[Dennis’] clock is made from several cylindrical blocks of ice stacked on top of one another. There are six columns of ice blocks. The blocks were made by pouring water into empty margarine containers and freezing them. Once they were frozen, [Dennis] bore a 5/16″ hole into the bottom of each block to house an LED. Wires ran from the LEDs back into the drainage port of a cooler.
The cooler housed the main electronics. The LED controller board is of [Dennis’] own design. It contains six TLC59282 chips allowing for control of up to 96 LEDs. Each chip has its output lines running to two RJ45 connectors. [Dennis] couldn’t just use one because one of the eight wires in the connector was used as a common power line. The main CPU is an Arduino. It’s hooked up to a DS3234 Real Time Clock in order to keep accurate time. The oscillator monitors temperature in order to keep accurate time even in the dead of winter. Continue reading “Binary Clock Fit For Queen Elsa’s Ice palace”→
This delightful marketing ploy requires the listener to fabricate their own record out of ice. The band Shout Out Louds wanted to make a splash with their newest single. So they figured out how to make a playable record out of ice. The main problem with this is the grooves start to degrade immediately when the ice begins to melt. So they shipped a mold of the record and a bottle of water to a select few listeners (just ten in all). Hear the result in the video after the break.
Now if you want to make something like this for yourself we can help you out just a bit. The mold is made of silicone and it wasn’t so long ago that we saw a guide for those new to mold making. The raw material isn’t that hard to find either. The project above tried several different approaches and found the best results can be attained with plain old distilled water. No, the one hard part is figuring out how to make your own master. If you’ve got a way of doing this in the home lab, please tells us about it!
The project started off with a theater-style fog machine. The problem is that this fills a room with a thin foggy-haze that doesn’t take shape outdoors. He wanted that ankle-deep graveyard effect and had seen several examples online that use a fog-machine with a bucked of dry ice. He though he’d just use his own bucket full of regular ice and salt water. Inside the bucket seen above there is a 15′ coil of copper tubing through which the fog machine’s output is passed. On the other side of the bucket there’s a plastic tube that goes to a sheet of plastic meant to distribute the cooled fog.
The problem here is that the fog machine puts out a hot mist. When it hits the ice bath the mist condenses into liquid form and that’s the end of the fog. As he attests in the video after the break, the dry-ice fog hack isn’t pumping out fog. It’s just using the heated steam to pump out carbon-dioxide vapor boiling off of the dry ice.
Want some fancy ice for your next cocktail party? You can try to find spherical ice-cube trays but you won’t get the kind of results seen here. It turns out the trick to this isn’t how you freeze the water, it’s how you melt the ice.
[Brendan O’Connor] started this project after seeing an ice mold that could make beautiful shapes rather than just cubes. But the price tag was $1400. If he could make his own at a hackerspace we’d bet that would pay his membership for an entire year!
The concept is pretty simple. The video after the break shows the mold he was trying to recreate. It’s two hunks of metal with a shape milled into them. The mold is pre-heated, then an oversized hunk of ice is placed between the blocks. The heat melts away the parts you don’t want, and leaves a perfectly shaped ice orb in between. Gravity is responsible for pulling the mold halves together as they slide along some machined rods.
With a big hunk of scrap aluminum he milled two halves of a sphere. They can be sufficiently heated if held under running water, and a some leftover printer rails keep the two parts aligned as the ice orb is formed. Now [Brendan] just needs to work on his method of creating a crystal-clear ice block as a starter and he’ll have achieved total win.
The Electronic Frontier Foundation, long-time defenders of the common man’s rights in the electronic realm, has published a guide to keeping your digital devices private when entering the United States. It seems the defenders of freedom and liberty (ICE, DHS, TSA, and CBP) are able to take a few freedoms with your liberty at a border crossing by seizing your devices and copies of the data they store for up to five days. This requires no suspicion of wrongdoing, and copies of this data may be shared with other agencies thereby negating the five day limit.
Do you have a reason to protect your digital property? This is discussed in the paper. It may be confidential information, by way of a business contract or professional relationship (Doctors, Lawyers, Journalists, etc.). Or you may just want to keep your privacy on principle. No matter what your stance, the EFF has covered all the bases in this intriguing read. We think the best advice they give is to make an encrypted backup of your data on the internet, blank your computer before the border crossing, and restore it when you get to your destination. If you don’t have the data with you, it can’t be compromised. It that’s not an option, they have plenty of guidelines on cryptographic techniques.