PCB Antenna Reference Designs

PCB Antenna

Have you ever built a wireless project and weren’t sure how to make one of those awesome (and cheap!) PCB antennas? “What low-cost solutions does our Antenna Board #referencedesign contain?” said Texas Instruments (TI) recently via Twitter.  This older reference design contains some comprehensive designs for sub-1 GHz and 2.4 GHz antennas.

While TI’s documentation can be difficult to navigate, there are many hidden gems, and this is one of them. While TI created these designs for use with their wireless products, they will work on any device which utilizes the same wireless base frequency. For example, you could use any of the 2.4 GHz antennas with any Bluetooth, WiFi (2.4 GHz), or Bluetooth Low Energy chips. Simply open up their Antenna Selection Quick Guide document and navigate to the specific design for whichever antenna you would like to build.

For a more detailed overview of what goes into designing and testing a PCB antenna, check out this hack which we featured back in 2010. With the internet of things coming into its own, wireless projects will become more and more prolific, making PCB antennas more important than ever.

Wireless Charging… Have a Heart

wireless heart charger

[Gal Naim] recently finished off an awesome Valentine’s day present for special someone. It’s a wireless charging heart for your phone!

He already had the Qi wireless charger but wasn’t much of a fan as it “looks so boring”. So he took it apart to salvage the charging circuit for his new project. As luck would have it, the Qi is very simple on the inside — all he had to do was lengthen the power wires to the coil. He then designed his heart in SolidWorks — Don’t forget to check out our 3D Printering tutorials on this — and printed it out in a nice candy apple red. To maximize the charging current he’s left the inductive loop on the outside so it can be as close to the phone as possible — he spray painted it red and it actually looks pretty cool!

The next step was adding the wireless charging capability to the phone, we’ve covered how to add this to any phone before, but for [Gal] it was as simple as cutting down the Qi Receiver card to fit in the phone.

[Read more...]

Remote Controlled Lawn Mower Lets you Sit Back and Enjoy The Show

Lawn Mower

“Its hard to find people that actually WANT to mow their lawn.” A more true statement has never been made. [Kurt's] project turns an old lawn mower into a remote control lawn mower.

The first step of this build is to replace the front drive wheels with mini-bike tires which have built-in gear tooth sprockets. The rear wheels were then replaced with large caster wheels. The 12-24V DC motors and gear boxes used come from National Power Chair. While we have seen more complicated RC lawn mowers before, this project is a great way to get started. All that [Kurt] wanted was to make lawn mowing more fun, we believe that he has succeeded. This thing is very mobile and can turn on a dime. Check out the demo video after the break.

What’s next? Add a GPS, a Raspberry Pi, and a few other odds and ends. Tie it together with some clever programming and you will have your own autonomous lawn mower. Have you already created a completely autonomous lawn mower? Let us know!
[Read more...]

nrf24l01+ using 3 ATtiny85 pins


[Ralph] wasn’t satisfied with the required 5 control pins to drive his nrf24l01+ transceiver module, so he used this circuit needing just 3 pin using an ATtiny85.

One of the key components was to effectively drive the chip select (CSN) line from the clock (SCK) line. The nrf24l01+ needs the CSN line to transition from high to low on the beginning of a communication.  [Ralph] put the SCK line behind a diode, put a capacitor in parallel with the CSN line and altered the arduino-nrf24l01 library to encode extra delays for the clock line.  This allowed the CSN line to be driven by the SCK line. Subsequent line transitions during transmission happen too fast to charge the capacitor, leaving the CSN line in a low state.

After tying the chip enable line high and dropping the 5V power line to 1.9-3.6V across a red LED, [Ralph] had an ATtiny85 controlling a nrf24l01+ module.

Though deceptively simple, a very cool hack that opens up a couple more lines on the ATtiny85.

Router Robot a Promising Playground for Young Hacker


[Stephen Downward] has put together a very impressive Internet controlled robot. There are so many things about his video presentation (also embedded below) which we find delightful. Notably, it’s obvious that he knows what he’s talking about when discussing everything from the electronics chosen for the project, the mechanical assembly and the issues with its current state, as well as the software backend that gives him control of the rover.

The bulk of the rover is the Linksys WRT-54G router which he picked up at a thrift shop. This has been a popular model for building rovers for quite some time. [Stephen] is not driving directly from the router’s serial port, but that could be an adventure for him down the road. For now he’s using an Arduino Mega along with an Ethernet shield to connect the motors to his network. The IP camera on the front gives him the video feed to operate this completely over the Internet using his own program written in C#. He mentions that the CD wheels he has aren’t ideal because of their thin tread area (covered in masking tape) and the inaccurate mounting which leaves one of them at an angle. He’s hoping to design and print his own. He plans rent some time on a 3D printer at the local University when their 3D printing service comes back online.

We think the hardest part with robot building is getting your first platform up and running. Now that he’s got that it’s a matter of making improvements and add-ons. Since he’s got the I/O of the Mega at his disposal we’d like to see him implement a bunch of different sensor: line following, bump sensors, distance sensor, heck… maybe someday he’ll scavenge some Lidar for it!

[Read more...]

Are We Not Indestructible? We Are Quiz Buttons!

In what we hope is a new trend in interviewing, some of the people at [Anthony]‘s place of work asked him to make some wireless quiz buttons. He took the task quite seriously, making them extremely robust and low-power.

[Anthony] is experienced in the button arts, having made this party push button for a wedding reception. His design for the quiz buttons is a little different. Each button has an Arduino Pro mini and an nRF24L01 wireless RF module. On the receiver side is an Arduino Pro micro and an another RF module. A connected PC captures the serial data and  displays the pressed button’s ID. It also shows the order in which subsequent buttons were pressed and the time elapsed between them.

The really notable part of this build aside from the awesome laser-cut MDF Devo energy dome button housings is the extremely low power consumption of the transmitting Arduinos. [Anthony] has designed them to go into sleep mode which disables all on-board circuitry and only wakes on interrupt. He removed the power LED and the voltage regulator since they run on 2-AA batteries. The voltage regulator was drawing more than 25mA in sleep mode. Because of these mods, each button consumes < 1μA, which is less power than the batteries can self discharge over their lifetime.

[Thanks Jef]

Fail of the Week: Reverse Engineering a Wireless Energy Monitor


[Afonso] picked up a cheap energy use monitor a few years back. He really like the data it displays about his home’s electricity, using a sensor to gather this info and a display that communicates with it wirelessly. But there is no option to log or dump the data. He set out to reverse engineer the wireless protocol in order to extend the use of the system. As the name of this column implies, he failed to get this working.

The hardware above is a 433Mhz transceiver that he rigged up as test hardware. It sounds like he’s assuming the monitor works on this band, which could have been his first misstep (we really don’t know). The speaker is there to give audible confirmation that he’s receiving something from the transmitter. This is where things start to get pretty weird. White noise was coming from the speaker, but when he stepped away from the bench it stopped. He was able to measure a regular pattern to the noise, and proceeded to place the speaker next to his computer MIC so that he could record a sample for further analysis.

Fail of the Week always aims to be a positive experience. In this case we’d like to have a conversation about the process itself. We agree that connecting a speaker (or headphones) should help get your foot in the door because your ear will recognize a rhythmic pattern when it is received. But with this noise, measuring the timing and recording a sample we’re not so sure about. Given the situation, how would you have soldiered on for the best chance at successfully sniffing out the communication scheme used by this hardware? Leave a comment below!

2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story – or sending in links to fail write ups you find in your Internet travels.