Not Your Typical POV Clock

Persistence of vision displays are fun, and a natural for clocks, but they’re getting a little Nixie-ish, aren’t they? There are only so many ways to rotate LEDs and light them up, after all. But here’s something a little different: a POP, or “persistence of phosphorescence” clock.

[Chris Mitchell] turned the POV model around for this clock and made the LEDs stationary, built into the tower that holds the slowly rotated display disk. Printed from glow-in-the-dark PLA, the disk gets charged by the strip of UV LEDs as it spins, leaving behind a ghostly dot matrix impression of the time. The disk rotates on a stepper, and the clock runs on a Nano with an RTC. The characters almost completely fade out by the time they get back to the “write head” again, making an interesting visual effect. Check it out in the video after the break.

Our only quibble is the choice to print the disk rather than cut it from sheet stock. Seems like there has to be commercially available phosphorescent plastic, or even the glow-in-the-dark paper used for this faux LED scrolling sign. But if you’ve got glowy PLA, why not use it?

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Optical Tach Addresses the Need for Spindle Speed Control

With CNC machines, getting the best results depends on knowing how fast your tool is moving relative to the workpiece. But entry-level CNC routers don’t often include a spindle tachometer, forcing the operator to basically guess at the speed. This DIY optical spindle tach aims to fix that, and has a few nice construction tips to boot.

The CNC router in question is the popular Sienci, and the 3D-printed brackets for the photodiode and LED are somewhat specific for that machine. But [tmbarbour] has included STL files in his exhaustively detailed write-up, so modifying them to fit another machine should be easy. The sensor hangs down just far enough to watch a reflector on one of the flats of the collet nut; we’d worry about the reflector surviving tool changes, but it’s just a piece of shiny tape that’s easily replaced.  The sensor feeds into a DIO pin on a Nano, and a small OLED display shows a digital readout along with an analog gauge. The display update speed is decent — not too laggy. Impressive build overall, and we like the idea of using a piece of PLA filament as a rivet to hold the diodes into the sensor arm.

Want to measure machine speed but don’t have a 3D printer? No worries — a 2D-printed color-shifting tach can work too.

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Man-in-the-Middle Jog Pendant: Two Parts Make Easier Dev Work

In a project, repetitive tasks that break the flow of development work are incredibly tiresome and even simple automation can make a world of difference. [Simon Merrett] ran into exactly this while testing different stepper motors in a strain-wave gear project. The system that drives the motor accepts G-Code, but he got fed up with the overhead needed just to make a stepper rotate for a bit on demand. His solution? A grbl man-in-the-middle jog pendant that consists of not much more than a rotary encoder and an Arduino Nano. The unit dutifully passes through any commands received from a host controller, but if the encoder knob is turned it sends custom G-Code allowing [Simon] to dial in a bit acceleration-controlled motor rotation on demand. A brief demo video is below, which gives an idea of how much easier it is to focus on the nuts-and-bolts end of hardware when some simple motor movement is just a knob twist away.

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Automate Wire Prep with a Robot Wire Cutter

When you move from one-off builds to production scale, perhaps to meet that Kickstarter commitment or to keep your Tindie store stocked, you’re going to need to tool up. Jobs like building wiring harnesses can be tedious and time-consuming, so outsourcing them to this robot wire cutter might be a good idea.

The video below tells the whole tale of this build, which despite the fact that [Maclsk] seems to have put it together quickly from scrap bin parts still looks pretty professional. The business end of the machine is a 3D printer extruder, minus the hot end, of course. A Nano controls the extruder’s stepper to shoot out the right length of wire, as well as the servo that squeezes the snippers. An LCD display and some pushbuttons provide the UI that rounds out the build. Tell it how long and how many, and you’ll be ready to build. We can see how this might be upgraded to strip the wires as well, although getting both ends stripped might be tricky.

Might this component tape-cutting robot from a few weeks back have inspired [Maclsk]’s build? Perhaps, but in any case, both are fun to watch.

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Mouse Mis-Clicking? We Got You.

A mouse with malfunctioning buttons can be a frustrating to deal with — and usually a short leap to percussive maintenance. Standard fixes may not always last due to inferior build quality of the components, or when the microswitch won’t close at all. But, for mice that double/triple-click, will release when dragging, or mis-click on release, this Arduino-based hack may be the good medicine you’re after.

Instructables user [themoreyouknow]’s method cancels click malfunctions by latching the mouse’s controller switch trace to ‘on’ when pressed, keeping it there until the button normally closed contact closes again completely. Due to the confined spaces, you’ll want to use the smallest Arduino you can find, some insulating tape to prevent any shorts, and care to prevent damaging the wires this process adds to the mouse when you cram it all back together.

Before you take [themoreyouknow]’s guide as dogma, the are a few caveats to this hack; they are quick to point out that this won’t work on mice that share two pins between three buttons — without doing it the extra hard way, and that this might be trickier on gaming or other high-end mice, so attempt at your own peril.

Speaking of gaming mice, we recently featured a way to add some extra functionality to your mouse — cheating optional — as well as how to stash a PC inside an old Logitech model.

Touchless MIDI: The Secret’s In the Mitten

MIDI is a great tool for virtually any musician. Unless you’re a keyboard player, though, it might be hard to use it live. [Evan] recently came up with a great solution for all of the wistful guitar players out there who have been dreaming of having a MIDI interface as useful as their pianist brethren, though. He created a touchless MIDI controller that interfaces directly with a guitar.

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Bring Doping, Microfluidics, Photovoltaics, and More Into the Home

Can you make a spectrometer for your home lab all from materials you have sitting around? We might not believe it from a less credible source, but this MIT course does indeed build a spectrometer from foam board using two razor blades as the silt cover and a writable CD as the diffraction grating. The coolest part is removing the metal backing of the CD.

mit_experiments_thumbHackaday reader [gratian] tipped us off about the course available from MIT courseware called Nanomaker. It boils down some fairly complicated experiments to the kind one can do in the home lab without involving thousands of dollars of lab equipment. The whole point is to demystify what we think of as complicated devices and topics surrounding photovoltaics, organic photovoltaics, piezoelectricity and thermoelectricity.

 

Spectrometers are used to analyze the wavelengths of a light source. Now that you have a measurement tool in hand it’s time to build and experiment with some light sources of your own. Here you can see an LED that is the topic of one of the course labs.

If you have a bit of background in chemistry this is a good step-by-step guide for getting into these types of experiments at home. It reminds us of some of the really cool stuff [Jeri Ellsworth] was doing in her garage lab, like making her own EL panels.

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