DIY KVM Switch Lets You Use One Keyboard and Mouse With Multiple Computers

Here’s a quick DIY hack if you happen to have multiple computers at home or at the office and are tired of juggling mice and keyboards. [Kedar Nimbalkar] — striving for a solution — put together a keyboard, video and mouse switcher that allows one set to control two computers.

A DPDT switch is connected to a female USB port, and two male USB cables — with the ground and 5V wires twisted together and connected to the switch — each running to a PC. [Nimbalkar] suggests ensuring that the data lines are correctly wired, and testing that the 5V and ground are connected properly. He then covered the connections with some hot glue to make it a little more robust since it’s about to see a lot of use.

Now all that’s needed is a quick press of the button to change which PC you are working on, streamlining what can be a tedious changeover — especially useful if you have a custom keyboard you want to use all the time.

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How Hot is Your Faucet? What Color is the Water?

How hot is the water coming out of your tap? Knowing that the water in their apartment gets “crazy hot,” redditor [AEvans28] opted to whip up a visual water temperature display to warn them off when things get a bit spicy.

This neat little device is sequestered away inside an Altoids mint tin — an oft-used, multi-purpose case for makers. Inside sits an ATtiny85 microcontroller  — re-calibrated using an Arduino UNO to a more household temperature scale ranging from dark blue to flashing red — with additional room for a switch, while the 10k ohm NTC thermristor and RGB LED are functionally strapped to the kitchen faucet using electrical tape. The setup is responsive and clearly shows how quickly [AEvans28]’s water heats up.

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Slow Dance Appears to Make Time Run In Slow Motion

Rendering something in slow-motion is an often-used technique that attempts to add some ‘wow’ or ‘cool’ factor. Seeing something out in the world move in slow motion is marginally rarer — rarer still if it’s in your own home. But do it right and that kind of novelty turns a lot of heads. Enough to go 8x on a Kickstarter goal.

Slow Dance, a picture frame ringed with strobe lights, generates the surreal effect of turning small, everyday objects into languid kinetic sculptures. It’s an intriguing example of kinetic art done in a novel way.

[Jeff Lieberman], a veteran of high-speed photography, takes advantage of ‘persistence of vision’ by synchronizing the vibrations of an object — say, a feather — with a strobe light blinking 80 times per second. An electromagnet inside the frame is used to vibrate the objects, while the strobe lights are housed inside the thick frame.

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Laser Pointer Clock Makes Timekeeping A Drawn-Out Affair

Designing a unique clock to flex your technical skills can be a rewarding experience and result in an admirable showpiece for your home. [Andres Robam] saw an opportunity to make a laser-pointer clock that draws the current time onto a glow-in-the-dark sticker.

A pair of stepper motors tilt and pan the laser’s mount — designed in SolidWorks and 3D printed. There was an issue with the motor’s shaft having some slack in it — enough to affect the accuracy of the laser. [Andres] cleverly solved the issue by using a pen’s spring to generate enough tension in the system, correcting it. A NODEmcu v2 is the brains of the clock — chosen because of its built-in WiFi capacity and compatibility with the Arduino IDE — and a 5mW laser sketches the time onto the sticker.

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Wii U RetroPie Console Looks Gorgeous

What to do with your broken gaming consoles? Gut it and turn it into a different gaming console! Sudomod forum user [banjokazooie] has concocted his own RetroPie console from the husk of a WiiU controller — an ingenious demonstration of how one can recycle hardware to a perfectly suited purpose.

[banjokazooie] actually used an original shell for this build, but if you happen to have a broken controller around — or know someone who does — this is a great use for it. A Raspberry Pi 3 is the brains of this operation (not counting [banjokazooie]), and it features a 6.5″ HDMI display, a Teensy 2.0 setup for the inputs, a headphone jack with automatic speaker disconnection, dual 3400 mAh batteries, an external SD card slot, and a lot of hard work on the power supply circuit — although [banjokazooie] reports that the hardest part was cutting to size a custom PCB to mount it all on. The original plan was to see if the idea was possible, and after a three month effort, it appears to work beautifully.

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Pi Cart: 2,400 Games In One

What’s the quickest way to turn one game into 2,400? Cram a Raspberry Pi Zero running RetroPie into an NES cartridge and call it Pi Cart.

This elegant little build requires no soldering — provided you have good cable management skills and the right parts. To this end, [Zach] remarks that finding a USB adapter — the other main component — small enough to fit inside the cartridge required tedious trial and error, so he’s helpfully linked one he assures will work. One could skip this step, but the potential for couch co-op is probably worth the effort.

Another sticking point might be Nintendo’s use of security screws; if you have the appropriate bit or screwdriver, awesome, otherwise you might have to improvise. Cutting back some of the plastic to widen the cartridge opening creates enough room to hot glue in the USB hub, a micro USB port for power, and an HDMI port in the resulting gap. If you opted to shorten the cables, fitting it all inside should be simple, but you may have to play a bit of Tetris with the layout to ensure everything fits.

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The Potowitzer: A Rapid Fire Potato Cannon

If you’ve ever fired a potato cannon, you’ll know that they are a raucous good time, but are somewhat clumsy to reload after each shot. Seeing an opportunity to improve on the design and minimize the delay between launches, [Danger First] have concocted a fast reloading potato cannon — or should I say — Potowitzer.

The key here is that they’ve gone through the extra effort of designing and building honest-to-goodness artillery rounds for their Potowitzer’s manual breech-loading mechanism. Foregoing the inconsistency of potatoes, they’ve 3D printed a bevy of bullets and sealed them with propane gas into PVC pipe cartridges. Metal contacts around the base to carry current from a BBQ lighter to the inside of the cartridge to ignite the propellant. Seeing it fire at about 18 rounds per minute is something special.

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