You’ve got several devices which communicate via the I2C protocol, but some of them can only operate at 3.3V while the rest are hungry for a 5V connection. What to do? [Linux-works] built this I2C level converter to solve the problem. The circuit comes from an NXP app note (PDF) on the issue. You can [...]

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[Afroman's] latest video shows you how to add reverse voltage protection with minimal power loss. At some point, one of your electronic concoctions will turn out to be very useful. You want to make sure that a battery plugged in the wrong way, or a polarity mistake with your bench PSU doesn’t damage that hardware. [...]

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[Dmitry Grinberg] has to walk all the way across his bedroom to switch the lamp on and off. The drudgery of this finally became too much, so he built a remote control and added dimming for good measure. Above you can see the circuitry for the remote and the receiver, as well as the finished [...]

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[Dino] is an auto mechanic and needed a way to test out fuel injectors. Commercially available tools start well over $100 and go up from there, but he built his own for about $20. The injectors have a coil in them that needs to be tested. His design calls for a series of 0.008 millisecond [...]

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Learn to manufacture your own solenoids and then use them to play the xylophone by watching the tutorial video after the break. [Humberto Evans] and the team at Nerd Kits do a great job of not only manufacturing the coils, but the xylophone itself. The bars are machined from some aluminum stock and they take [...]

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[Isaac] grabbed the motor from an old printer and used it to make a spider run up and down the wall for Halloween. A PIC 12F683 uses a MOSFET to drive the motor. The program loop has a little bit of dramatic flare to it, raising the arachnid with a bit of a jerky motion [...]

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Radio communications depend on stable oscillator frequencies and with that in mind, [Scott Harden] built a module to regulate temperature of a crystal oscillator. The process is outlined in the video after the break but it goes something like this: A small square of double-sided copper-clad board is used as a base. The body of [...]

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In [Dave's] latest episode of the EEVblog he takes a look at constant current dummy loads. These are used to test power supply designs and instead of just chaining resistive loads together every time he’s decided to look into building a tool for the job. What he ends up with is a reliable constant current [...]

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[Chris] is getting his feet wet with Computer Numerical Control starting with an Etch-a-Sketch interface. This is a great way to start out because the really tough parts of the project are already inside of the toy. He’s replaced the two white knobs with stepper motors and connected them through a mosfet network to a [...]

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