Teardown: Catel CTP300 Restaurant Pager

I have a problem. If I go to a swap meet , or even a particularly well stocked yard sale, I feel compelled to buy something. Especially if that something happens to be an oddball piece of electronics. While on the whole I’m a man of few vices, I simply can’t walk away from a good deal; doubly so if it has a bunch of buttons, LEDs, and antennas on it.

Table for one, by the window.

Which is exactly how I came into the possession of a Catel CPT300 restaurant paging system for just $20 a few months ago. I do not, as you may have guessed, operate a restaurant. In fact, as many of my meals take the form of military rations eaten in front of my computer, I’m about as far away from a restaurateur as is humanly possible. But I was so enamored with the rows of little plastic pagers neatly lined up in their combination charging dock and base station that I had to have it.

The man selling it swore the system worked perfectly. Even more so after he plugged it in and it didn’t do anything. But appearances can be deceiving, and his assurance that all the pagers needed was a good charge before they’d burst back to life seemed reasonable enough to me. Of course, it hardly mattered. The regular Hackaday reader at this point knows the fate of the CPT300 was to be the same whether or not it worked.

Incidentally, those cute little pagers would not burst back to life with a good charge. They may well have burst into something, but we’ll get to that in a moment. For now, let’s take a look at a gadget that most of us have used at one time or another, but few have had the opportunity to dissect.

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Sonic Screwdriver Shuts Off Mains

In the world of Doctor Who, the sonic screwdriver is a versatile tool with a wide range of capabilities. [Hartley] wanted some of that action for himself, and built a device of his own.

Unable to recreate the broad swathe of features from the show, he settled on something easier. The device is fitted with an ATTiny85, and a 433MHz transmitter. It’s programmed to switch wirelessly controlled mains sockets on and off. This lets him control appliances in his house with a flick of a screwdriver. Power is supplied by the classic AA battery, with a boost converter stepping it up to 5V to run the electronics.

It’s all wrapped up in a 3D printed case, that was carefully designed to fit all the parts inside. A paper mockup of the PCB layout was also used in the design phase. [Hartley] took full advantage of CAD software, to ensure everything fit correctly first time.

It’s a fun project, as sonic screwdrivers often are. Video after the break.

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3D Printed Weather Station Gets A Wireless Upgrade

A weather station can be anything from a fun home science exercise, all the way up to a useful tool for planning and weather prediction. [Rob Ward] is one such person who has developed their own weather station, and it recently got a wireless upgrade.

We first featured [Rob]’s work back in 2018, noting that a largely 3D-printed weather station was a particularly useful tool for the home experimenter. The utility of this is now improved, with the addition of a 433 MHz wireless link from the weather sensors back to the base station. Over on Github, [Rob] does a great job of explaining the basics of the Manchester encoding scheme used, and has developed a system that can decode signals from Oregon Scientific weather stations, too.

[Rob] uses the weather station to report weather conditions at Lake Tyers Beach, providing useful information for anyone in the area who might be considering a visit to the coast. It’s not quite as fun as asking whoever’s around on the CB road channel, but it’s a darn sight more accurate for your trouble. Video after the break.

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A New Digital Mode For Radio Amateurs

There used to be a time when amateur radio was a fairly static pursuit. There was a lot of fascination to be had with building radios, but what you did with them remained constant year on year. Morse code was sent by hand with a key, voice was on FM or SSB with a few old-timers using AM, and you’d hear the warbling tones of RTTY traffic generated by mechanical teletypes.

By contrast the radio amateur of today lives in a fast-paced world of ever-evolving digital modes, in which much of the excitement comes in pushing the boundaries of what is possible when a radio is connected to a computer. A new contender in one part of the hobby has come our way from [Guillaume, F4HDK], in the form of his NPR, or New Packet Radio mode.

NPR is intended to bring high bandwidth IP networking to radio amateurs in the 70 cm band, and it does this rather cleverly with a modem that contains a single-chip FSK transceiver intended for use in licence-free ISM band applications. There is an Ethernet module and an Mbed microcontroller board on a custom PCB, which when assembled produces a few hundred milliwatts of RF that can be fed to an off-the-shelf DMR power amplifier.

Each network is configured around a master node intended to use an omnidirectional antenna, to which individual nodes connect. Time-division multiplexing is enforced by the master so there should be no collisions, and this coupled with the relatively wide radio bandwidth of the ISM transceiver gives the system a high usable data bandwidth.

Whether or not the mode is taken up and becomes a success depends upon the will of individual radio amateurs. But it does hold the interesting feature of relying upon relatively inexpensive parts, so the barrier to entry is lower than it might be otherwise. If you are wondering where you might have seen [F4HDK] before, we’ve previously brought you his FPGA computer.

RTL-SDR Paves Way To Alexa Controlled Blinds

You’d be forgiven for occasionally looking at a project, especially one that involves reverse engineering an unknown communication protocol, and thinking it might be out of your league. We’ve all been there. But as more and more of the devices that we use are becoming wireless black boxes, we’re all going to have to get a bit more comfortable with jumping into the deep end from time to time. Luckily, there are no shortage of success stories out there that we can look at for inspiration.

A case in point are the wireless blinds that [Stuart Hinson] decided would be a lot more useful if he could control them with his Amazon Alexa. There’s plenty of documentation on how to get Alexa to do your bidding, so he wasn’t worried about that. The tricky part was commanding the wireless blinds, as all he had to go on was the frequency printed on the back of the remote.

Luckily, in the era of cheap RTL-SDR devices, that’s often all you need. [Stuart] plugged in his receiver and fired up the incredibly handy Universal Radio Hacker. Since he knew the frequency, it was just a matter of tuning in and hitting the button on the remote a couple times to get a good capture. The software then broke it down to the binary sequence the remote was sending out.

Now here’s where [Stuart] lucked out. The manufacturers took the easy way out and didn’t include any sort of security features, or even bother with acknowledging that the signal had been received. All he needed to do was parrot out the binary sequence with a standard 433MHz transmitter hooked up to an ESP8266, and the blinds took the bait. This does mean that anyone close enough can take control of these particular blinds, but that’s a story for another time.

We took a look at the Universal Radio Hacker a year or so back, and it’s good to see it picking up steam. We’ve also covered the ins and outs of creating your own Alexa skills, if you want to get a jump on that side of the project.

Speaking The Same Language As A Wireless Thermometer

Temperature is a delicate thing. Our bodies have acclimated to a tight comfort band, so it is no wonder that we want to measure and control it accurately. Plus, heating and cooling are expensive. Measuring a single point in a dwelling may not be enough, especially if there are multiple controlled environments like a terrarium, pet enclosure, food storage, or just the garage in case the car needs to warm up. [Tim Leland] wanted to monitor commercially available sensors in several rooms of his house to track and send alerts.

The sensors of choice in this project are weather resistant and linked in his project page. Instead of connecting them to a black box, they are linked to a Raspberry Pi so your elaborate home automation schemes can commence. [Tim] learned how to speak the thermometer’s language from [Ray] who posted about it a few years ago.

The system worked well, but range from the receiver was only 10 feet. Thanks to some suggestions from his comments section, [Tim] switched the original 433MHz receiver for a superheterodyne version. Now the sensors can be a hundred feet from the hub. The upgraded receiver is also linked on his page.

We’ve delved into thermocouple reading recently, and we’ve featured [Tim Leland] and his 433MHz radios before.

Radio Decoding Swiss Army Knife In A NES Controller

If you wanted to name a few things that hackers love, you couldn’t go wrong by listing off vintage console controllers, the ESP system-on-chip platform, and pocket tools for signal capture and analysis. Combine all of these, and you get the ESP32Thang.

At its heart, the ESP32Thang is based around a simple concept – take an ESP32, wire up a bunch of interesting sensors and modules, add an LCD, and cram it all in a NES controller which helpfully provides some buttons for input. [Mighty Breadboard] shows off the device’s basic functionality by using an RFM69HW module to allow the recording and replay of simple OOK signals on the 433 MHz band. This is a band typically used by all sorts of unlicenced radio gear – think home IoT devices, wireless doorbells and the like. If you want to debug these systems when you’re out and about, this is the tool for you.

This is a fairly straightforward build at the lower end of complexity, but it gets the job done with style. The next natural step up is a Raspberry Pi with a full software defined radio attached, built into a Nintendo DS. If you build one, be sure to let us know. This project might serve as some inspiration.

With the wide availability of SPI and I2C modules these days, combined with the ease of programming provided by the Arduino environment, this is a project that just about any hacker could tackle after passing the blinking LED stage. The fact that integrating such hardware is so simple these days is truly a testament to the fact that we are standing on the shoulders of giants.