FruitNanny: The Raspberry Pi Baby Monitor For Geeks

October 21, 2017 by Tom Nardi 14 Comments

Having a child is perhaps the greatest “hack” a human can perform. There’s no soldering iron, no Arduino (we hope), but in the end, you’ve managed to help create the most complex piece of machinery in the known galaxy. The joys of having a child are of course not lost on the geekier of our citizens, for they wonder the same things that all new parents do: how do we make sure the baby is comfortable, how many IR LEDs do we need to see her in the dark, and of course the age old question, should we do this with a web app or go native?

If you’re the kind of person who was frustrated to see that “What to Expect When You’re Expecting” didn’t even bother to mention streaming video codecs, then you’ll love FruitNanny, the wonderfully over-engineered baby monitor created by [Dmitry Ivanov]. The product of nearly two years of development, FruitNanny started as little more than a Raspberry Pi 1n a plastic lunch box. But as [Dmitry] details in his extensive write-up, the latest iteration could easily go head-to-head with products on the commercial market.

[Dmitry] gives a full bill of materials on his page, but all the usual suspects are here. A Raspberry Pi 3 paired with the official NoIR camera make up the heart of the system, and the extremely popular DHT22 handles the environmental monitoring. A very nice 3D printed case, a lens intended for the iPhone, and a dozen IR LEDs round out the build.

The software side is where the project really kicks into high gear. Reading through the setup instructions [Dmitry] has provided is basically a crash course in platform-agnostic video streaming. Even if a little bundle of joy isn’t on your development roadmap, there’s probably a tip or two you can pick up for your next project that requires remote monitoring.

It probably won’t surprise you that geeky parents have been coming up with ways to spy on their kids for some time now, and if you can believe it, some don’t even include a Raspberry Pi.

Look What Came Out Of My USB Charger !

October 21, 2017 by Anool Mahidharia 6 Comments

Quick Charge, Qualcomm’s power delivery over USB technology, was introduced in 2013 and has evolved over several versions offering increasing levels of power transfer. The current version — QCv3.0 — offers 18 W power at voltage levels between 3.6 V to 20 V. Moreover, connected devices can negotiate and request any voltage between these two limits in 200 mV steps. After some tinkering, [Vincent Deconinck] succeeded in turning a Quick Charge 3.0 charger into a variable voltage power supply.

His blog post is a great introduction and walk through of the Quick Charge ecosystem. [Vincent] was motivated after reading about [Septillion] and [Hugatry]’s work on coaxing a QCv2.0 charger into a variable voltage source which could output either 5 V, 9 V or 12 V. He built upon their work and added QCv3.0 features to create a new QC3Control library.

To come to grips with what happens under the hood, he first obtained several QC2 and QC3 chargers, hooked them up to an Arduino, and ran the QC2Control library to see how they respond. There were some unexpected results; every time a 5 V handshake request was exchanged during QC mode, the chargers reset, their outputs dropped to 0 V and then settled back to a fixed 5 V output. After that, a fresh handshake was needed to revert to QC mode. Digging deeper, he learned that the Quick Charge system relies on specific control voltages being detected on the D+ and D- terminals of the USB port to determine mode and output voltage. These control voltages are generated using resistor networks connected to the microcontroller GPIO pins. After building a fresh resistor network designed to more closely produce the recommended control voltages, and then optimizing it further to use just two micro-controller pins, he was able to get it to work as expected. Armed with all of this information, he then proceeded to design the QC3Control library, available for download on GitHub.

Thanks to his new library and a dual output QC3 charger, he was able to generate the Jolly Wrencher on his Rigol, by getting the Arduino to quickly make voltage change requests.

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3D Printed Gear Serves Seven Months Hard Labor

October 20, 2017 by Tom Nardi 32 Comments

Even the staunchest 3D printing supporter would have to concede that in general, the greatest strength of 3D printing is not in the production of final parts, but in prototyping. Sure you can make functional prints, as the pages of this site will attest; but few would argue that you wouldn’t be better off getting your design cut out of metal or injection molded if you planned on putting the part into service over the long term. Especially if the part was to be subjected to rough service in an industrial setting.

While that’s valid advice, it certainly isn’t the definitive word on the issue. Just because a part is printed in plastic on a desktop 3D printer doesn’t necessarily mean it can’t be put into real service, at least for as long as it takes to get proper replacement parts. A recent success story from [bloomautomatic] serves as a perfect example, when one of the gears in his MIG welder split, he decided to try and print up a replacement in PLA while he waited for the nylon gear to get shipped out to him. Fast forward seven months and approximately 80,000 welds later, and [bloomautomatic] reports it’s finally time to install those replacement gears he ordered.

In the pictures [bloomautomatic] posted you can see the printed gear finally wore down to the point the teeth were essentially gone where they meshed with their metal counterparts. To those wondering why the gear was plastic to begin with, [bloomautomatic] explains that it’s intended to be a sacrificial gear that will give way instead of destroying the entire gearbox in the event of a jam. According to the original post he made when he installed the replacement gear, the part was printed in Folgertech PLA on a Monoprice Select Mini. There’s no mention of infill percentage, but with such a small part most slicers would likely have made it essentially solid to begin with.

While surviving seven tortuous months inside of the welder is no small feat, we wonder if hardier PLA formulations, treatment of the part post-printing, or even casting it in a different material couldn’t have turned this temporary part into a permanent replacement.

Supercon Badge Hacking Quick-Start

October 20, 2017 by Mike Szczys 8 Comments

The hardware badge Mike Harrison designed for this year’s Hackaday Superconference is begging to be hacked. Today, I wanted to help get you up and running quickly.

The Hacker Village atmosphere of Supercon is starting up a day early this year. On Friday, November 10th badge pick-up starts at noon and badge hacking continues throughout the afternoon, followed by a party at Supplyframe HQ that evening. Plan to get to town on Friday and join in the fun. Of course, you need to grab a Supercon ticket if you haven’t already.

Check out the 2017 Superconference Badge project page for full documentation that Mike has put together during his development process.

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Cheap RC Truck Mod Is Slightly Risky Fun

October 19, 2017 by Tom Nardi 32 Comments

The world of RC can be neatly split into two separate groups: models and toys. The RC models are generally big, complex, and as you’d imagine, more expensive. On the other hand, the RC toys are cheap and readily available. While not as powerful or capable as their more expensive siblings, they can often be a lot of fun; especially since the lower costs means a crash doesn’t put too big of a ding into to your wallet.

With his latest mod, [PoppaFixIt] has attempted to bridge the gap between toy and model by sticking a considerably overpowered battery into a $10 RC truck from Amazon. He reports greatly improved performance from his hacked together truck, but anyone looking to replicate his work should understand the risks before attempting to hack up their own version.

The principle is pretty simple; the truck is designed to run on two AA batteries, providing 3 volts. But by swapping the AAs out for a 3.7 volt 1S LiPo of the type that’s used in small airplanes and quadcopters, you can get an instant boost in power. As a happy side effect, the LiPo batteries are also rechargeable and fairly cheap, so you won’t have to keep burning through alkaline AAs.

The mod itself is a basic job that only requires a few bucks in parts, and for which [PoppaFixIt] has helpfully provided Amazon links. Essentially you just crack open the truck, solder a JST connector pigtail to the positive and negative traces on the PCB, and then pop a hole in the roof to run the new battery wires out.

Right about now the RC purists are probably screaming obscenities at their displays, and not without reason. As fun as these supercharged little trucks are to drive, there are a number of real issues here which need to be mentioned.

First, while the motor will probably be alright with a bit higher voltage running through them, the gears won’t be liking it one bit. In fact, [PoppaFixIt] even mentions they shredded a few gears when they tried to take one off-road. The second issue is that since these vehicles were not designed with LiPo batteries in mind, there’s no low voltage cutoff to prevent over discharge. If you aren’t careful, a setup like this will cook those cute little batteries in short order. But hey, at least it’s all cheap.

If you are more interested in control than power, you may want to check out the previous hacks we’ve featured. Seems like these little RC trucks are the platform of choice for hackers who want to get stuff moving on the cheap.

Why Not Expose Your PCBs Through An LCD?

October 16, 2017 by Jenny List 67 Comments

Most people who have dabbled in the world of electronic construction will be familiar in some form with the process of producing a printed circuit board by exposing a UV sensitive coating through a transparent mask, before moving on to etching. Older readers will have created their masks by hand with crêpe paper tape on acetate, while perhaps younger ones started by laser-printing from their CAD package.

How about a refinement of the process, one which does away with the acetate mask entirely? [Ionel Ciobanuc] may have the answer, in the form of an exposure through an LCD screen. The video below the break shows how it’s done, starting with a (probably a bit too lengthy) sequence on applying the photo-resist coating to the board, and then sitting LCD on top of UV lamp with the board positioned at the top of the pile.

It’s an interesting demonstration, and one that certainly removes a step in the process of PCB creation as it brings the pattern direct from computer to board without an intermediate. Whether or not it’s worth the expenditure on an LCD is up to you, after all a sheet of acetate is pretty cheap and if you already have a laser printer you’re good to go. We’re curious to know whether or not any plastic components in the LCD itself might be damaged by long-term exposure to intense UV light.

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Xerox Alto CRTs Needed A Tiny Lightbulb To Function

October 15, 2017 by Al Williams 61 Comments

In the real world, components don’t work like we imagine they do. Wires have resistance, resistors have inductance, and capacitors have resistance. However, some designers like to take advantage of those imperfections, something our old friend [Ken Shirriff] noted when he was restoring the CRT of a Xerox Alto.

[Ken] tried to connect a Xerox monitor to the Alto and — since it was almost as old as the Alto — he wasn’t surprised that it didn’t work. What did surprise him, though, is that when he turned the monitor off, a perfect picture appeared for just a split second as the unit powered off. What could that mean?

Keep in mind this is a CRT device. So a perfect picture means you have vertical and horizontal sweep all at the right frequency. It also means you have high voltage and drive on the electron guns. If you are too young to remember all that, [Ken] covers the details in his post.

He found that the CRT grid voltage wasn’t present during operation. The voltage derived from the high voltage supply but, mysteriously, the high voltage was fine. There was a small lightbulb in the grid voltage circuit. A 28V device about like a flashlight bulb. It measured open and that turned out to be due to a broken lead. Repairing the broken lead to the bulb put the monitor back in operation.

On paper, a light bulb lights up when you put current through it. In real life, it is a bit more complicated. An incandescent filament starts off as almost a dead short and draws a lot of current for a very brief time. As the current flows, the filament gets hot and the resistance goes up. That reduces the current draw. This effect — known as inrush current — is the scourge of designers trying to turn on light bulbs with transistors or other electronic switches.

However, the unknown Xerox power supply designer used that effect as a current limiter. The short 600V pulses would hardly notice the light bulb but if too much current or time elapsed, the resistance of the bulb would rise preventing too much current from flowing for too long. With the bulb open, the negative brightness grid provided an impassible barrier to the electrons. Apparently, the brightness grid lost power a bit earlier than the rest of the circuit and with it out of the way — or perhaps, partially out of the way — the picture was fine until the rest of the circuit also lost power.

We looked at [Ken’s] efforts on this machine earlier this year. Light bulbs, by the way, aren’t the only thing that changes resistance in response to some stimulus. You might enjoy the 1972 commercial from Xerox touting the Alto’s ability to do advanced tasks like e-mail and printing.

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