$100 hot water bottle pendulum rebreather


Humans exhale a lot of oxygen along with their waste carbon dioxide. Instead of throwing out this oxygen, a rebreather uses a scrubber to remove the CO2 and replace it with pure oxygen from a bottle. Tom Rose built this rebreather for $100. When you exhale air passes through the scrubbing material and is stored in hot water bottle counterlung until you inhale. The system is only 15 pounds; a great savings compared to most dive equipment. You are definitely putting your life in your own hands so this should not be used without plenty of “couch-diving” tests. Tom has a ton of other diving related projects on his site.

[via Divester]

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UV box for PCB exposure

uv box

Hack-A-Day reader [Mindaugasu] built this box for exposing copper boards to ultraviolet light before etching them. It has two banks of four 20W UV lamps. The box is lined with reflective foil. The banks can be controlled separately and the exposure time is set by an Atmel AT90. You can change the time using button panel and LCD. He’s got some example boards in his ARM development section.

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Commercial-grade TIG welder

tig welder

I use the qualifier “commercial-grade” here because this TIG welder project goes far beyond our junkyard TIG welder. The welder has a 180 amp capacity and has most (if not all) of the features of a modern welder. Instead of using a microprocessor, Dave Barrett decided to use discrete TTL and CMOS logic. That decision should make the design a lot easier to troubleshoot. Schematics and board layouts are on his site.

[UPDATE: I forgot to thank demmion for the tip]

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sCrAmBlEd? HaCkZ!

scrambled hackz

This story as appeared many different places [via Music thing], but I wanted to make sure you guys didn’t miss out on the fun. sCrAmBlEd? HaCkZ! by Sven K? is an amazing piece of video remixing software. It’s built using C++, Python and PureData. It takes music videos, chops them up by beats and indexes the samples by sound signature in a database. You then beatbox into a microphone to describe the music you want to hear. The software builds the music you want out of the sample database. Sven has put together an excellent video that describes the program and has example performances. It’s a must watch. Get it either directly from his site or watch it on YouTube.

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Laser listening device

laser listener

Laser based listening devices work by bouncing the beam off of a window. Sounds in the room cause minute vibrations in the window. These vibrations modulate the laser beam. The laser beam is then converted back into sound at the receiver. Hack-A-Day reader [Aaron v] decided to build one of these devices. It worked, but needs some improvement. He followed plans found here (Coral CDN cache). I’ve also got a local copy of the receiver schematic since there doesn’t seem to be too many of these projects with decent hosting. Williamson Labs has a good discussion of the problems these systems can run into and more advanced setups like interferometry.

Shacktopus, the next step in technomadics


Steve Roberts has been doing technomadics since 1983. You’ll probably remember him from his 580-pound BEHEMOTH bicycle which he was checking his email on in 1991 over satellite. Shacktopus is his latest project. His previous vehicles all had heavily integrated systems, but because of that you couldn’t just grab the communication system and run. Shacktopus is an easy to pack communications platform that contains multiple RF and sensing technology into one device. HF, VHF, UHF, Bluetooth, WiFi, cellular communication are all there plus GPS and environmental sensors. Here’s a block diagram of the device. Now, no matter what vehicle you choose to head off into the wild with you’ll be able to communicate with the rest of the world using one device.

[thanks fbz]
[UPDATE: fixed name]

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