2014 Advent Calender of Circuits

Every day this month and until Christmas, [vk2zay] is (has already been!) posting a simple but useful hack in his 2nd sort-of-annual “Advent Calender of Circuits” that many of you will want to be bookmarking. For those already saturated with the season of holiday hacks, don’t worry – other than being festively generous of him to tutor and demo a new hack every day, the hacks themselves have nothing to do with Christmas. Though he missed the last couple years we here at Hackaday covered his first month of hacks back in 2011 (now in playlist).

The daily hacks posted so far cover a wide variety of useful projects (leaning towards HV) for the electronics hobbyist who might not have all the fancy tools in their shop: DIY high voltage probes, a 1-hour tesla coil from junk, measuring RF power, a stud detector, how to test an  unknown transformer’s saturation, and many others. We cannot predict what will be posted the rest of the calender (the author hints to be making them up as he goes), but by now it is safe to say that they will not disappoint.

We would be stealing his thunder to cover them all, so, we will just pick our favorite for now:

The 1-hour tesla coil is a delightful all-shortcuts-taken hack project. If one were to listen to aficionados, teslacoiling is a highly precise hobby to get into. It appears to require careful planning, much calculation, special-ordered or soviet-surplus parts, custom jigs, fine tuning, etc. [vk2zay] shows otherwise.

Every single component of the assembly is itself a hack.

No fancy tungsten-infused grade 8 copper being water-cooled via heat pump here – the spark gap is just the bent leg of a capacitor hovering near the start of the primary winding. The power supply is a backlight inverter with a chain of Cockcroft-Walton voltage doublers. The high voltage resistor is a bunch of series-chained resistors shoved into a silicone tube. The topload is a couple cheap pie tins masking-taped together to “resemble something like a sphere.” The primary is a loose, unsupported spring of copper wire. The secondary was calculated to be whatever the height of the tube he had handy and coiled only as smoothly as a first attempt would allow. He does not even bother using wires or a switch – the circuit is completed by clipping a couple of test leads.

After all this hodgepodgery the circuit was then carefully tuned to optimize how little time it took to build (additional time used: zero). Since the frequencies do not match (1.7 vs. 2.6 mhz – 35% apart) the only thing this circuit resonates with is a hacker’s appeal for making do. Does not matter, still works. The streamers easily reach 2 inches and the author claims double that in dark lighting.

In the just 6 minute video he also manages to explain roughly what is going on theory-wise and suggest the time-effective things to considering upgrading. Almost a dozen hacks in the bag and over a dozen more to come before Christmas.

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Christmas Lights And Ships In A Bottle

Thanksgiving was last week, and Christmas has been invading department stores for two or three months now, and that can only mean one thing: it’s time to kill a tree, set it up in your living room, and put a few hundred watts of lights on it. All those lights, though; it’s as if Christmas lights were specifically invented as fodder for standup comedians for two months out of the year. Why can’t someone invent wireless Christmas lights?

We don’t know if it’s been invented, but here’s a Kickstarter campaign that’s selling that same idea. It’s called Aura, and it’s exactly what it says on the tin: wireless Christmas lights, controllable with a smartphone. If it works, it’s a brilliant idea.

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Five Dollar RF Controlled Light Sockets

This is tens of thousands of dollars worth of market research I’m about to spill, so buckle up. I have a spreadsheet filled with hundreds of projects and products that are solutions to ‘home automation’ according to their creators. The only common theme? Relays. Home automation is just Internet connected relays tied to mains. You’re welcome.

[Todd] over at Fabricate.io found an interesting home automation appliance on Amazon; a four-pack of remote control light sockets for $20, or what we would call a microcontroller, an RF receiver, and a relay. These lamp sockets are remote-controlled, but each package is limited to four channels. Terrible if you’re trying to outfit a home, but a wonderful exploration into the world of reverse engineering.

After cracking one of these sockets open, [Todd] found the usual suspects and a tiny little 8-pin DIP EEPROM. This chip stores a few thousand bits, several of which are tied to the remote control. After dumping the contents of the EEPROM from the entire four-pack of light sockets, [Todd] noticed only one specific value changed. Obviously, this was the channel tied to the remote. No CRC or ‘nothin. It doesn’t get easier than this.

With the new-found knowledge of what each lamp socket was looking for, [Todd] set out to clone the transmitter. Tearing this device apart, he found a chip with HS1527 stamped on it. A quick Googling revealed this to be an encoder transmitter, with the datasheet showing an output format of a 20-bit code and four data bits. This was a four-channel transmitter, right? That’s where you put each channel. The 20-bit code was interesting but not surprising; you don’t want one remote being able to turn of every other 4-pack of lamp sockets.

With all the relevant documentation, [Todd] set out to do the obvious thing – an Arduino transmitter. This was simply an Arduino and a transmitter in the right frequency, loaded up with bit of carefully crafted code. [Todd] also figured out how to expand his setup to more than four lamp sockets – by changing the 20-bit code, he could make his Arduino pretend to be more than one transmitter.

With Arduino-controlled lamp sockets, the world is [Todd]’s oyster. He can add Ethernet, WiFi, Bluetooth LE, and whatever trendy web front end he wants to have a perfect home automation setup. It’s actually a pretty impressive build with some great documentation, and is probably the cheapest way to add Arduino/Internet-enabled relays we’ve ever seen.


Retrotechtacular: How to Teletypewriter

This week, you’re going to learn the ins and outs of the AN/GRC-46 thanks to this army training film from 1963. What is the AN/GRC-46, you ask? Why it’s a complete mobile-tactical sheltered radio-teletypewriter rig capable of CW, voice, and teletype transmission.

The film covers the components that make up the AN/GRC-46, their functions, the capabilities of the system, and proper operation procedures. There’s a lot going on in the tiny 1400lb. steel shelter, so each piece will be introduced from the ground up.

You’ll become familiar with the voltage distribution system and the AN/GRC-46’s included accessories. This introduction will be followed by a short course in RF signal transmission and the Frequency-Shift Keying (FSK) that is performed by the modulator. The ranges of both the transmitter and receiver are discussed, along with the capabilities mentioned before: CW operation using the keyer, voice operation, teletype operation, and reperforation of teletype tape.

Finally, you’ll observe a seasoned operator make contact and send a teletype message with movements so careful and deliberate that they border on mesmerizing. When he’s not sending messages or taking long walks on the beach, he can usually be found cleaning and/or lubricating the transmitter filter.

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THP Quarterfinalist: 3GHz Spectrum Analyzer

Radio seems to be an unofficial theme for The Hackaday Prize, with a few wireless frameworks for microcontrollers and software defined radios making their way into the quarterfinal selection. [roelh]’s project is a little different from most of the other radio builds. It’s a simple spectrum analyzer, but one that works up to 3GHz.

The hardware is a mishmash of chips including an ADL5519 power detector, an Si4012 for the local oscillator, and a MAX2680 mixer. An Atmel XMega takes care of all the on board processing, displaying the spectrum on a small LCD, writing data to an SD card, and sending data over a 3.5mm jack that doubles as either an analog input or a half duplex RS232 port.

Seen in the video below, [roelh]’s spectrum analyzer is more or less finished, complete with a nice looking enclosure. Now [roelh] is working on documentation, porting his source to English, and getting all the files ready to be judged by our real judges.

SpaceWrencherThe project featured in this post is a quarterfinalist in The Hackaday Prize.

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How To: Hack Your Way Into Your Own Gated Community

RF Signal Decryption and Emulation

Does your Gated Community make you feel secure due to the remote-controlled gate keeping the riffraff out? Residents of such Gated Communities in Poland are now shaking in fear since [Tomasz] has hacked into his own neighborhood by emulating the signal that opens the entrance gate. Shockingly, this only took about 4 hours from start to finish and only about $20 in parts.

Most of these type of systems use RF communication and [Tomasz’s] is no difference. The first step was to record the signal sent out by his remote. A USB Software Defined Radio transmitter/receiver coupled with a program called SDR# read and recorded the signal without a hitch. [Tomasz] was expecting a serialized communication but after recording and analyzing the signal from several people entering the community it became clear that there was only one code transmitted by everyone’s remote.

Now that he knows the code, [Tomasz] has to figure out a way to send that signal to the receiver. He has done this by making an RF transmitter from just a handful of parts, the meat and potatoes being a Colpitts oscillator and a power amplifier. This simple transmitter is connected to a DISCOVERY board that is responsible for the modulation tasks. [Tomasz] was nice enough to make his code available on his site for anyone that is interested in stopping by for a visit.

A Modular 1GHz Spectrum Analyzer


[MrCircuitMatt] has been doing a lot of radio repair recently, quickly realized having a spectrum analyzer would be a useful thing to have. Why buy one when you can build one, he thought, and he quickly began brushing up on his RF and planning out the design of a 1000 MHz spectrum analyzer

The project is based on Scotty’s Spectrum Analyzer, a sweep-mode, modular 1GHz spectrum analyzer that is, unfortunately, designed entirely in ExpressPCB. [Matt] didn’t like this proprietary design software tied to a single board house. The basic building blocks of [Scotty]’s spectrum analyzer were transferred over to KiCAD, the boards sent off to a normal, Chinese board house.

In the second video, [Matt] goes over the design of the control board, a small module that connects the spectrum analyzer to the parallel port of a PC. There’s a lot of well thought out design in this small board, a good thing, too, since he’s powering his VCO with a switched mode supply. The control board has a 32-bit I/O, so how’s he doing that with a parallel port, what is ultimately an 8-bit port? A quartet of 74ACT573, a quad buffer with latch enable. Using the eight data lines on the parallel port allows him to toggle some pins while the ancient pins on the parallel bus – Strobe, Select Printer, and Line Feed control the latches on each of the buffers. This gives him the ability to write to 32 different pins in his spectrum analyzer with a parallel port.

Right now, [Matt] is wrapping up the construction of his control board, with the rest of the modules following shortly. He thinks the completed analyzer might even be cheaper than a professional, commercial offering, and we can’t wait to see another update video.

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