Tint Your Epoxy Resin With Toner Powder

September 4, 2015 by Dan Maloney 67 Comments

Epoxy resin is useful stuff. Whether for gluing stuff together or potting components, epoxy is a cheap and versatile polymer that finds its way into many hackish projects. But let’s face it – the stock color of most commercially available epoxies lacks a certain pizzazz. Luckily, [Rupert Hirst] at Tallman Labs shows us that epoxy is easily tinted with toner powder from a laser printer or copier.

Looking for a way to make his epoxy blend into a glue-up, [Rupert] also demonstrates that colored epoxy makes a professional looking potting compound. There’s just something about the silky, liquid look of a blob of cured black epoxy. [Rupert] harvested his toner powder from a depleted printer cartridge; only a smidgen is needed, so you should be able to recover plenty before recycling the cartridge. We’ve got to admit that seeing toner handled without gloves gives us the willies, though. And don’t forget that you can find cyan, magenta and yellow cartridges too if basic black isn’t your thing.

Sometimes it’s better to leave your epoxy somewhat clear, like when you’re potting an LED matrix for a pendant. But this neat trick might just spiff up your next project a bit.

[Thanks, Jake]

How To Build Anything Using Delrin And A Laser Cutter

September 3, 2015 by Sonya Vasquez 58 Comments

Need a simple fab process to go from a humble vector graphic to a final part — in a matter of minutes? The CO₂ laser cutter might be the right choice. As these tools open themselves up to widespread use through hackerspaces, I decided to give Delrin some well-deserved time under the spotlight.

The laser cutter yet-again proves itself a formidable tool with the construction of GameCube-Bot V2

This guide is a brief collection of tips and techniques that I’ve either learned from others or discovered on my own over the last couple years working with laser-cut Delrin (a.k.a Acetal) for functional prototypes. I hope this guide serves you well as we keep exploring the limits of the material.

As a disclaimer, keep in mind that in no way are these techniques unique or limited to Delrin. Many are not only years old but also common practice in either engineering design or the local machine shop. This article simply highlights the techniques shown here that perform both repeatably and predictably with Delrin and a couple hand-tools, and I hope to share them with a growing audience of laser cutter enthusiasts.

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Recycled Factory Recycles Soda Bottles

September 2, 2015 by Dan Maloney 32 Comments

All over the world, mountains of polyethylene terephthalate (PET) plastics are available for recycling in the form of soda bottles. And wherever there is enough cheap raw material, a market is sure to emerge for it. One brilliant inventor in Brazil has decided to capitalize on this market by building a magnificent factory to turn PET bottles into threads, rope, and other products.

Not a word of English is spoken in the video, and our Portuguese stops at obrigado, but you don’t really need to understand what’s being said to know what’s going on. Built from what looks to be the running gear of several bicycles and motors from various cast-off appliances, our nameless genius’ machines slit the PET bottles into fine threads, winds the thread onto spools, and braids the threads into heavier cords. We love the whole home-brew vibe of the machines; especially clever is the hacked desk calculator wired to a microswitch to count revolutions, and the salvaged auto jack used to build a press for forming the broom heads. All in all it’s a pretty amazing little factory cranking out useful products from zero-cost raw material.

We’d love to have more context about what’s being said in the video, so we’ll put this one out there for our Portuguese-speaking readers. Maybe we can get a partial translation in the comments? If so, then obrigado.

[Thanks W4RIS]

Shift Register Powered Realistic Candle Flicker

August 29, 2015 by George Graves 54 Comments

[Kevin Darrah] recently went out to dinner at a restaurant that was using some cheap LED candles (yuck) instead of the real thing. And in the true spirit of a hacker, he started to notice the patterns programmed into the fake flame repeat over and over again. And like any hacker might, his mind started to devise a better way.

Now’s the time where some of us lazy hackers might grab a microcontroller, and copy and paste in some pseudo-random number generating code you found on the Internet, but not [Kevin]. The basics of his hack uses two shift registers tied together that are fed a single clock signal, and also a latch signal that is slightly delayed version of the same signal made by a RC-time circuit.

The randomness of the output is created is by feeding back the outputs of the shift registers to an XOR gate. If you want to learn more about this, the technique it’s called a “linear feedback shift register“. It’s commonly used as a poor-man’s random number generator, although it’s not technically truly random, statistically it does a very good job. You can see the results in the video after the break where [Kevin] describes the circuit. He wraps up the hack with a battery and solar charging circuit as well to make a completed project.

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Cheap Function Generator Teardown And Improvement

August 28, 2015 by Dan Maloney 19 Comments

In general, you get what you pay for, and when [Craig] picked up a cheap function generator off eBay, he didn’t expect much from it. But as he shows us in his blog post and a series of videos below, while the instrument lived down to his expectations, he was able to fix it up a bit.

Having spent only $100USD for the MHS-5200A, [Craig]’s adventure is a complete teardown and analysis of the function generator. While it sort of lives up to its specs, it’s pretty clear that some design decisions resulted in suboptimal performance. At higher frequencies and higher amplitudes, the sine wave output took on a markedly non-sinusoidal character, approaching more of a triangle waveform. The spectrum analyzer told the tale of multiple harmonics across the spectrum. With a reverse-engineered schematic in hand, he traced the signal generation and conditioning circuits and finally nailed the culprit – an AD812 op-amp used as the final amplifier. An in-depth discussion of slew rate follows in part 2, and part 3 covers replacement of the dodgy chip with a better selection that improves the output signal. We’re also treated to improvements to a low-pass filter that fixed a nasty overshoot and ringing problem with the unit’s square wave function.

If hacking the MHS-5200A seems a bit familiar to you, that’s because we covered another reverse-engineering exploit of it recently. That hack of the serial protocol of the instrument was by [WD5GNR], also known as Hackaday’s own [Al Williams]. Cheers to both [Craig] and [Al] for showing us what you can do with a hundred bucks and a little know-how.

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Hackaday Prize Entry: Feral Cats Phone Home With Das Katzetelegraf

August 23, 2015 by Dan Maloney 41 Comments

Feral cats are a huge problem in some areas. Roaming freely in cities and in rural settings and reproducing with reckless abandon, colonies of feral cats can exhibit nuisance behavior that often results in unpleasant measures being taken to control their population. More humane programs, such as trap-neuter-return (TNR), seek to safely trap cats, give them basic vaccinations and neuter them, and either return them to their colony or, for a lucky few, ready them for adoption. Such programs are proving successful, but are not without issues. Enter Das Katzetelegraf.

You don’t need to understand a lick of German to figure out exactly what Das Katzetelegraf does from its name. Consisting of an Arduino, a GSM module, and a simple magnetic reed switch attached to the door of a humane cat trap, Das Katzetelegraf sends a text message to a TNR program volunteer when a cat has been trapped. Instead of waiting in the trap for the TNR workers to make daily rounds, the cats are quickly retrieved and the trap is reset for the next cycle. This reduces the time the cat spends in the trap, stressed and without access to food or water, and improves the animal’s outcome. As a bonus, each trap’s throughput is increased, so more animals can be cycled through the TNR program.

TNR can really help reduce feral cat populations, and Das Katzetelegraf can make them even more effective. But if you just have a stray cat pooping up your garden, a Raspberry Pi cat-deterring sprinkler might be a better choice.

The 2015 Hackaday Prize is sponsored by:

Fight Frost With An Internet Of Things Fridge Alarm

August 23, 2015 by Dan Maloney 12 Comments

It has been incredibly humid around these parts over the last week, and there seems to be something about these dog days that makes you leave the fridge or freezer door open by mistake. [pnjensen] found this happening all too often to the family chill chest, with the predictable accretion of frost on the coils as the water vapor condensed out of the entrained humid air and froze. The WiFi-enabled fridge alarm he built to fight this is a pretty neat hack with lots of potential for expansion.

Based on a Sparkfun ESP8266 Thing and home-brew door sensors built from copper tape, the alarm is rigged to sound after 120 seconds of the door being open. From the description it seems like the on-board buzzer provides a periodic reminder pip while the door is open before going into constant alarm and sending an SMS message or email; that’s a nice touch, and having the local alarm in addition to the text or email is good practice. As a bonus, [pjensen] also gets a log of each opening and closing of the fridge and freezer. As for expansion, the I2C header is just waiting for more sensors to be added, and the built-in LiPo charger would provide redundancy in a power failure.

If frost buildup is less a problem for you than midnight snack runs causing another kind of buildup, you might want to check out this willpower-enhancing IoT fridge alarm.