Reverse Geocache box looks great and packed with features

[Ranger Bob] crafted this great looking Reverse Geocache box. Our favorite feature is the black piece of acrylic on top. It’s laser cut (not sure if the letters are engraved or not) and gives a great finished look while hiding a couple of things at the same time.

The orange box is a metal cash box, and there’s a smooth indentation in the lid where the handle resides when not being carried. [Bob] removed the handle and mounted the GPS module in that void. But there’s also an OLED display mounted next to it. As you can see in the demo video after the break, the screen is bright enough to be seen clearly through the smoky acrylic covering that depression.

This project gave [Bob] the chance to order his first professionally made circuit board. He did the design in Eagle, managing to keep within the 5cmx5cm limits of Seeed Studio’s least expensive Fusion PCB option. The board hosts the PIC 18F87J50 responsible for handing the screen, GPS module, input button, and USB port. Power comes from an internal Lithium battery.

We’ve featured a lot of Reverse Geocache boxes and they’re still one of our favorite projects because so much love goes into the design and build process. Here’s another one that we chose randomly for your amusement.

[Read more...]

Doom for your calculator gets a color upgrade

You’re not still playing nDoom in black and white, are you? What decade do live in? Thankfully, the Doom port for TI-nspire calculators has been upgraded to support color. That is if you’ve got the hardware to run it.

The video after the break (and the image above) shows a TI-nspire CX running the popular first-person-shooter. It’s seen several upgrades since the beta version which we saw piggy-backed with a different TI-83 hack a year ago. The control scheme has been tweaked, and a menu system was added. It’s not the same on-screen menu that you would see with the DOS version of the game, but it accomplishes that same thing. This port is packaged with the Ndless program that unlocks the hardware so that you can perform your own hacks.

Unfortunately there is still no sound available for the game but that is a project for a different time. We know it must be possible because we’ve seen a TI-84+ used to play music stored on a thumb drive. [Read more...]

Building a Variable Frequency Drive for a three-phase motor

Here are the power and driver boards that [Miceuz] designed to control a three-phase induction motor. This is his first time building such a setup and he learned a lot along the way. He admits it’s not an industrial quality driver, but it will work for motors that need 200 watts or less of power.

The motor control board uses an MC3PHAC driver IC and an IRAMS06UP60A handles the power side of things. The majority of the board design came from studying the recommended application schematics for these two parts. But that’s far from all that goes into the setup. Motor drivers always include levels of protection (the whole reason to have a driver in the first place) and that comes in several different forms. [Miceuz] made sure to add EMI, over voltage, and over current protection. He discusses all of these, sharing links that explain the concepts of each.

Reusing an old pacemaker as a flash timer


Most people use pacemakers to, you know, keep their heart pumping at a steady rhythm. [David Prutchi] on the other hand has found a pretty novel use for some of the old pacemakers he has in his collection.

We really had no idea that pacemakers had uses outside the world of medicine, but [David] has taken advantage of their reliability in one of his favorite hobbies – high speed photography. In a darkened room, he set up an infrared barrier which feeds its signal to the atrium input of an old pacemaker. The signal is relayed through the ventricular output, which then fires his camera’s flash.

The pacemaker allows [David] to set an “AV” delay, which is the interval between when the atrium input receives an electrical impulse and when that signal is repeated from the ventricular output. This allows him to finely tune how much time elapses from when a drop of milk breaks the IR barrier to when his flash actuates.

We think this is a pretty cool way to reuse an old pacemaker, but check out the shots he has captured and judge for yourself.