Clever Battery Holder Hack Makes Brilliant Earrings

A ‘googly eye’ with hole for LED leads on one side, slot for coin cell on the other. Black disk for pupil removed.

We love seeing a thing get used effectively for other than its intended purpose, and this DIY LED Earrings project is a great example. [IdunnGoddess] liked the idea of making light-up LED earrings powered by a small coin cell, but an enclosure and power connection for the battery were sticking points. The solution? A googly eye after a few minor modifications turned out to be perfect.

A googly eye resembles a thin, flat, hollow plastic bulb. Choose one that’s just a bit bigger than the coin cell, and cut a slot in one end and a small hole in the other. The LED leads go into the hole, and the coin cell slides into the slot. The result? A lightweight battery holder for an attached LED, and as a bonus the hacked googly eye is a clean and super smooth surface that can easily be painted or decorated to make it part of the design. The video embedded below demonstrates the process and showcases a few sample designs.

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Edge-lit Pendants Show Two Layers are Better Than One

Engraved acrylic lights up nicely with LED lighting. Simply engrave clear acrylic with a laser engraver, then edge-light the acrylic and watch the engraving light up. This badge made by [Solarbotics] shows how they used this principle when creating some pendants for an event that performed particularly well in the dark.

The pendants they created have two engraved acrylic panels each, and that’s about it. Two LEDs and a CR2032 battery nestle into pre-cut holes, and the engraved sides are placed face-to-face, so the outer surfaces of the pendant are smooth. By using some color-cycling RGB LEDs on one panel and blue LEDs on the other panel, the effect is that of an edge-lit outer design with a central element that slowly changes color separately from the rest of the pendant.

The design stacks the LED leads and coin cells in such a way that a simple wrap of tape not only secures things physically, but also takes care of making a good electrical connection. No soldering or connectors of any kind required. [Solarbotics] found that CR2032 cells would last anywhere between a couple of days to a week, depending on the supplier.

This design is great for using a minimum of materials, but if that’s not a priority it’s possible to go much further with the concept. Multiple layers of edge-lit acrylic were used to make numeric 0-9 display modules as well as a full-color image.

 

Mitosis: Anatomy of a Custom Keyboard

Ergonomic. Wireless. Low-latency. Minimalist. Efficient. How far do you go when you design your own open-source keyboard? Checking off these boxes and providing the means for others to do so, Redditor [reverse_bias] presents the Mitosis keyboard, and this thing is cool.

The custom, split– as the namesake implies — mechanical keyboard has 23 keys on each 10 cm x 10 cm half, and, naturally, a custom keymapping for optimal personal use.

Upper and lower PCBs host the keys and electronic circuits respectively, contributing to the sleek finished look. Key caps and mechanical switches were ripped from sacrificial boards: two Waveshare core51822 Bluetooth modules are used for communication, with a third module paired with a Pro Micro make up the receiver. Continue reading “Mitosis: Anatomy of a Custom Keyboard”

Chronio DIY Watch: Slick and Low Power

[Max K] has been testing the battery life of his self-designed watch under real-world conditions. Six months later, the nominally 3 V, 160 mAh CR2025 cell is reading 2.85 V, so the end is near, but that’s quite a feat for a home-engineered smart watch.

We’ve tipped our hats to the Chronio before in this Hacklet, but now that the code is available, as well as the sweet 3D-printed case files, it’s time to make your own. Why? It looks sweet, it plays a limited version of Flappy Bird (embedded below), and six month’s on a button cell is a pretty great accomplishment, considering that it’s driving a 96×96 pixel LCD display.

The Chronio is more than inspired by the Pebble watch — he based his 3D model directly on theirs — so that’s bound to draw comparisons. The Pebble is color, and has Bluetooth and everything else under the sun. But after a few weeks away from a power socket, ask a Pebble wearer what time it is. Bazinga!

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PSA: Don’t Let Kids Eat Lithium Batteries

We get a lot of press releases at Hackaday, but this one was horrific enough that we thought it was worth sharing. Apparently, some kids are accidentally eating lithium coin cell batteries. When this happens with bigger cells, usually greater than 20 millimeters (CR2032, CR2025, and CR2016) really bad things happen. Like burning esophaguses, and even death.

The National Capital Poison Center has done some research on this, and found that 14% of batteries swallowed over the past two years came from flameless candles like the ones above. We know some of our readers also deal with batteries in open trays, which are apparently pretty dangerous for children.

The National Capital Poison Center’s website has an entire page dedicated to battery safety, which is probably worth a read if you deal with batteries and small children on a regular basis. Should an incident occur, there’s even a hotline to call for assistance.

So, please, don’t swallow batteries, or let children put them in their mouths. After the break, a Canadian PSA song about not putting things in your mouth.

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What is the Matrix…Clock?

We’re surprised we haven’t seen this kind of clock before, or maybe we have, but forgot about it in the dark filing cabinets of our minds. The above picture of [danjhamer’s] Matrix Clock doesn’t quite do it justice, because this is a clock that doesn’t just tick away and idly update the minutes/hours.

matrix clock

Instead, a familiar Matrix-esque rain animation swoops in from above, exchanging old numbers for new. For the most part, the build is what you would expect: a 16×8 LED Matrix display driven by a TLC5920 LED driver, with an Arduino that uses a DS1307 RTC (real-time clock) with a coin cell battery to keep track of time when not powered through USB. [danjhamer] has also created a 3D-printed enclosure as well as added a piezo speaker to allow the clock to chime off customizable musical alarms.

You can find schematics and other details on his Hackaday.io project page, but first, swing down below the jump to see more of the clock’s simple but awesome animations.

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A Vibrating Timepiece

vibratingWatch

It may not look like much, but the above pictured device is [qquuiinn’s] handy little watch that indicates time through pulsed vibrations. Perhaps we should refrain from labeling it as a “watch,” however, considering it’s [qquuiinn’s] intention to remove the need to actually look at the thing. Vibrations occur in grandfather clock format, with one long vibration for each hour, accompanied by one, two, or three short pulses for the quarter-hour increments.

The design is straightforward, using an ATTiny85 for the brains along with a few analog components. The vibration motor sticks to the protoboard with some glue, joining the microcontroller, a coin cell battery, and a pushbutton on a small protoboard. The button allows for manual time requests; one press responds with the current time (approximated, probably) in vibrations. The build is a work in progress, and [qquuiinn] acknowledges the lack of an RTC (real-time clock) causes some drift in the timepiece’s accuracy. We suspect, however, that you’d address that problem—twice daily—when you replace the battery: it only lasts ten hours.