[Mike Worth] wanted the option to run his Microwave Oven Transformer welding rig at less that full power. After being inspired by some of the other MOT hacks we’ve featured he figured there must be a lot of ways to do this. But his searches on the topic didn’t turn up anything. So he just designed and built his own adjustable current limiter for the welder.
At the beginning of his write-up he details what we would call a bootstrap procedure for the welder. Go back and check out his original build post to see that he had been holding the framework for the cores together using clamps. To make the setup more robust he needed to weld them, but this is the only welder he has access to. So he taped some wood shielding over the coils and fired it up.
The current limiter itself is built from a third MOT. Adjustment is made to the cores by changing out the E and I shaped pieces. This allows for current limiting without altering the windings. [Mike] holds it all in place with a couple of bicycle wheel quick connect skewers.
It just goes to show that you should never get rid of a microwave without pulling the transformer. Even if you don’t need a welder wouldn’t you love a high-voltage bug zapper?
Voice activation, one-touch cooking, web controls, cooking settings based on UPC… have you ever seen a microwave with all of these features? We sure haven’t. We thought it was nice that ours have a reheat button with three different settings. But holy crap, what if you could actually program your microwave to the exact settings of your choice? You can, if you let a Raspberry Pi do the cooking.
This hack run deep and results in a final product with a high WAF. Nathan started by taking apart his old microwave. He took pictures of the flexible sheets that make up the control button matrix in order to reverse engineer their design. This led him to etch his own circuit board to hook the inputs up to a Raspberry Pi board and take command of all the appliance’s other hardware. Because it also drives the seven segment display you’ll never see the wrong time on this appliance again. It’s set based on NTP.
We mentioned you can tweak settings for a specific food. The best way of doing this is shown in the demo video. The web interface is used to program the settings. Recalling them is as simple as using the barcode reader to scan the UPC. Amazing.
Now you can keep that old microwave working, rather than just scraping it for parts.
Continue reading “The most advanced microwave you’ll ever own”
This is the biggest bug zapper we’ve ever seen. It’s called the Megazap as its zapping area is 1 square meter. [Eighdot] and [Sa007] combined their talents for the build in order to help reduce the insect population around the Eth0 2012 Summer festival.
You may recall from our bug zapping light saber build that these devices work by providing two energized grids. When an insect flies between the grids it allows the potential energy to overcome the air resistance by travelling through the insect’s body. The Megazap uses a transformer from a microwave oven to source that potential. The transformer produces 2.4 kV and the current is limited by a floodlight fitted inside the microwave. The side effect of using the lamp as a limiter is that it lights up with each bug zapped, providing a bit of a light show. Don’t miss the video after the break to see some flying foes get the life shocked out of them.
Continue reading “A huge microwave-powered bug zapper”
Transformers certainly have a tendency to increase the cost of any project, especially if you need a large transformer to get the job done. Microwave ovens are great sources of free transformers, though they are not always in the shape required for your next build.
[Matt] put together three great tutorial videos covering the basics of salvaging Microwave Oven Transformers (MOTs), that anyone new to the process should watch before giving it a go. The first video covers MOT removal and disassembly, which is a time consuming yet easy process providing you follow [Matt’s] pointers.
The second video delves into transformer theory, and discusses how to achieve optimal performance when rebuilding an MOT or hand wrapping coils to fit your project specs. The third video in the series follows [Matt] as he rebuilds one of the salvaged transformers, documenting his pitfalls and successes along the way.
If you haven’t given much thought to salvaging MOTs, we definitely recommend taking a bit of time to watch the video series in full – it’s definitely worth it.
You can see the first video in the series after the jump – the rest can be found via the YouTube link above.
Continue reading “Tutorial series shows you everything you need to salvage transformers from microwaves”
[Shahriar] is back with a new “The Signal Path” video. It has been a few months but it is okay because his videos are always packed full of good information. Some new equipment has been added to his lab and as an added bonus a quick tour of the equipment is included at the start, which is great if you like drooling over sweet machines.
The real focus of the video is high speed data communications, getting up into the GHz per second range. [Shahriar] covers filtering techniques from simple RC low pass filters to pretty complex microwave filters. Explaining frequency and time domain measurements of a 1.5Gbps signal through a low bandwidth channel. He also shows how equalization can be used to overcome low bandwidth limitations.
It is an hour long video jam packed with information, so you might want to set aside some time and have a pencil on hand before going in. It is well worth it though, so join us after the break.
Continue reading “Passive Filters, Data Transmission and Equalization Oh My!”
Behold the uWave, a microwave oven that plays YouTube videos while it cooks. [Kevin] and three classmates at the University of Pennsylvania developed the project for the 2011 PennApps hackathon. It uses a tablet computer to replace the boring old spinning food display microwaves are known for. Now, an Arduino reads the cook time and sends that information to a server via its Ethernet shield. The server then searches YouTube for a video that approximately matches the cooking time, then pushed that video to the tablet to start playing. The video demonstration embedded after the break shows this, as well as the tweet that the machine sends at the beginning of the process.
It’s an interesting concept, and we think the code used to push a video to the tablet has a lot of other applications (we’re keeping this one bookmarked). On the other hand, we wonder how long it will take for public microwaves to become ad-supported? We’re thinking it’s hard for companies selling antacids, acid reflux medicine, Cup ‘o Soup, and Hot Pockets to resist this opportunity.
Continue reading “Kitchen Hacks: Microwave plays YouTube videos matched to your cooking time”
Instructables user [Rohit] had an out-of-warranty microwave with a broken membrane keypad. Much like our friend [Alexandre] from Brazil, he found the cost of replacement parts beyond reasonable, so he had to find a way to repair it instead.
He disassembled the front cover of his microwave to get at the main controller board. Once it was detached, he removed the keypad’s cover to get a closer look at the matrix underneath. While taking notes on how the matrix was wired, he found that some keypad traces connected to other traces rather than buttons. He says that they are likely used by the microwave to detect that the keypad is present, so he made sure to short those traces out on the controller board when he wired everything back together.
He replaced the aging keypad with microswitches, but rather than mount them on the front panel of the microwave, he drilled holes for each switch so that he could mount them inside the face plate. Once everything was wired and glued in place, he re-mounted the keypad’s cover. Now the microwave looks stock but has firm, reliable, user-serviceable buttons that are sure to last quite a while.