Feline Genetics And Why Orange Cats Are The Most Special

June 9, 2025 by Maya Posch 43 Comments

Recently, butlers to orange-colored cats got a bit of a shock when reading the news, as headlines began to call out their fuzzy feline friends as ‘freaks of nature’ and using similarly uncouth terms. Despite the name-calling, the actual reason for this flurry of feline fascination was more benign — with two teams of scientists independently figuring out the reason why some cats have fur that is orange. Tracking down the reason for this turned out to be far more complicated than assumed, with the fact that about 80% of orange cats are male being only the tip of the cat-shaped iceberg.

It was known to be an X chromosome-linked mutation, but rather than the fur coloring being affected directly, instead the mechanism was deduced to be a suppression of the black-brownish pigmentation (eumelanin) in favor of the orange coloration (pheomelanin). Finding the exact locus of the responsible ‘O gene’ (for orange) in the cat genome has been the challenge for years, which turned out to be a mutation related to the X-linked ARHGAP36 gene, whose altered expression results in the suppression of many melanogenesis genes.

Interestingly, this particular mutation appears to be of a singular origin that apparently persisted over millennia courtesy of the domestication of humans (H. sapiens) by Felis catus.

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2025 Pet Hacks Contest: A Water Fountain For Your Cat

May 25, 2025 by Jenny List 5 Comments

Part of the charm of having a cat in your life is that by their nature these animals are very interactive. They will tell you in no uncertain terms when something in their lives needs attention, for example when their water dish is empty. But why not give them a drinking fountain all of their own? It’s what [supermarioprof] did for their adorable ginger cat [Piki Piki], providing a cat-operated trickle of water on demand.

It’s a simple enough device in its operation, but very well constructed. There’s a small basin with a drain, and a water cistern valve operated by the cat placing a paw on a lever. This starts a trickle of water, from which they can lap as much as they like.

The physical construction comes courtesy of some laser-cut ply, and what looks like some 3D print work. It’s certainly easy to operate for the cat, and has worked reliably for a few years now.

This project is part of the 2025 Pet Hacks contest, so expect to see more in the same vein. If your cat’s life is improved by one of your projects, consider making an entry yourself!

RFID From First Principles And Saving A Cat

November 23, 2024 by Dan Maloney 5 Comments

[Dale Cook] has cats, and as he readily admits, cats are jerks. We’d use stronger language than that, but either way it became a significant impediment to making progress with an RFID-based sensor to allow his cats access to their litterbox. Luckily, though, he was able to salvage the project enough to give a great talk on RFID from first principles and learn about a potentially tragic mistake.

If you don’t have 20 minutes to spare for the video below, the quick summary is that [Dale]’s cats are each chipped with an RFID tag using the FDX-B protocol. He figured he’d be able to build a scanner to open the door to their ~~playpen~~ litterbox, but alas, the read range on the chip and the aforementioned attitude problems foiled that plan. He kept plugging away, though, to better understand RFID and the electronics that make it work.

To that end, [Dale] rolled his own RFID reader pretty much from scratch. He used an Arduino to generate the 134.2-kHz clock signal for the FDX-B chips and to parse the returned data. In between, he built a push-pull driver for the antenna coil and an envelope detector to pull the modulated data off the carrier. He also added a low-pass filter and a comparator to clean up the signal into a nice square wave, which was fed into the Arduino to parse the Differential Manchester-encoded data.

Although he was able to read his cats’ chips with this setup, [Dale] admits it was a long road compared to just buying a Flipper Zero or visiting the vet. But it provided him a look under the covers of RFID, which is worth a lot all by itself. But more importantly, he also discovered that one cat had a chip that returned a code different than what was recorded in the national database. That could have resulted in heartache, and avoiding that is certainly worth the effort too.

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CATS mobile transceiver in a 3d-printed case

CATS: A New Communication And Telemetry System

March 15, 2024 by Dave Rowntree 29 Comments

CATS is a new communication and telemetry standard intended to surpass the current Automatic Packet Reporting System (APRS) standard by leveraging modern, super-cheap Frequency Shift Keying (FSK) transceivers rather than standard FM units. The project is in the early stages, but as of this writing, there is a full open source software stack and reference hardware for both Raspberry Pi-based gateway devices and an STM32-based mobile device.

CATS packets are called ‘whiskers!’

From a radio perspective, CATS uses raw FSK rather than the inefficient AFSK used by APRS. A real killer for channel utilization is the PTT time; this is the dead time around a packet APRS requires for ‘keying up’ and ‘keying down.’ The CATS standard is aggressive with PTT timing, enabling the channel to get going on sending the data sooner.

Additionally, compared to APRS, the packet baud rate increases from 1200 baud to 9600 baud. Other key points are using LDPC encoding for forward error correction and data whitening (a useful PDF guide from Ti) to smooth over any burst errors.

One of the neat concepts of APRS is the APRS-IS (APRS Internet service). This enables amateur radio services to be connected over the Internet, vastly improving range. The CATS equivalent is called FELINET (if you’re not spotting all the ‘cat’ references by now, go and get another coffee). Together with the I-gate hardware, FELINET bridges the CATS radio side with the current APRS network. As FELINET expands to more than the current few dozen nodes, APRS services will no longer be required, and FELINET may well replace it. Interestingly, all software for FELINET, the APRS relay, and the I-Gate firmware are written in Rust. We told you learning Rust was going to be worth the effort!

On the reference hardware side of things, the CATS project has delivered a Raspberry Pi hat, which uses a 1 watt RF4463 transceiver and supporting passives. The design is about as simple as it can be. A mobile transceiver version uses an STM32 micro to drive the same RF4463 but with supporting power supplies intended to run from a typical automotive outlet. Both designs are complete KiCAD projects. Finally, once you’ve got some hardware in place and the software installed, you will want to be able to debug it. CATS has you covered with an RTL-SDR I-Gate module, giving you an independent packet log.

APRS is quite mature, and we’ve seen many hacks on these pages. Here’s an earlier APRS IGate build using a Raspberry Pi. Need to hook up your PC to a cheap Chinese transceiver? You need the all-in-one cable. As with many things amateur-radio-oriented, you can get playing cheaply.

A cat sits on a dark green mid-century modern bench next to a cat-sized black piano. A black bowl sits beneath the piano to catch food. An abstract green, blue, and tan picture in a black frame is on the wall above the cat and a black bar stool can be seen around the corner. It looks like the sort of photo you'd see on Instagram or in an interior design magazine.

Piano Feeder Gets Pets Playing For Their Supper

February 29, 2024 by Navarre Bartz 21 Comments

If you ever watched a video of Piano Cat and wondered if your cat could learn to play, then [Sebastian Sokołowski] has a possible solution with this combination piano tutor and cat feeder.

Starting with a CNC cut MDF enclosure, [Sokołowski] developed a cat feeder that would fit in the rear of the piano. It had to be reliable, consistent, and easy to disassemble. He walks us through his testing for each of these features and says the feeder was the most difficult part of the project to develop due to the propensity of pet feeder mechanisms to jam.

A custom PCB takes the key presses from the piano (with functional black keys) and outputs the sound from a speaker in the back. Lessons progress through increasing difficulty automatically, encouraging your cat to learn what the different keys can do. Food is dispensed after a performance or on a schedule set through the accompanying smartphone app. All the files are available if you want to build your own, but there is a wait list available if you want a completed version to give to less technically-inclined cat staff.

We’re certainly no stranger to the creatures that rule the internet here at Hackaday, having featured other cat feeders, new research into spaying cats, or even open source robo-cats.

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Cat-o-Matic 3000 Serves Your Feline Masters

December 1, 2023 by Kristina Panos 8 Comments

When you have three cats and three humans, you have one problem: feeding them on a schedule without over or under feeding them. Even if there was only one human in the equation, the Cat-o-Matic 3000 would still be a useful tool.

Essentially, it’s a traffic light for cats — where green means you are go for feeding, and red means the cat was just fed. Yellow, of course, means the cat is either half-full or half-empty, depending on your outlook.

The brains of this operation is an ATmega88PA leftover from another project. There’s a no-name voltage regulator that steps up the two AA cells to 5 volts. Timing comes from a 32 kHz crystal that allows the microcontroller to stay in power-saving sleep mode for long periods of time.

Creator [0xCAFEAFFE] says the firmware was cobbled together from other projects. Essentially, it wakes up once per second to increment the uptime counter and then goes back to sleep. Short-pressing a button shows the feeding status, and long-pressing it will reset the timer.

Wanna make a cat status indicator without electronics? Give flexures a try.

Spaying Cats In One Shot

June 12, 2023 by Navarre Bartz 61 Comments

Feral cats live a rough life, and programs like Trap, Neuter, Release (TNR) attempt to keep their populations from exploding in a humane way. Researchers in Massachusetts have found a non-surgical way to spay cats that will help these efforts.

A single dose of anti-Müllerian hormone (AMH) gene therapy suppresses ovarian follicle formation, essentially turning off the ovulation cycle. After following the test cats for two years, none had kittens, unlike the cats in the control group. Other major hormones like estrogen were unaffected in the cats and they didn’t exhibit any negative side effects. The researchers said it will be some time before the treatment can be widely deployed, but it offers hope for helping our internet overlords and the environs they ~~terrorize~~ inhabit.

For those of you doing TNR work, you might want to try this trap alert system to let you know you’ve caught a cat for spaying or neutering. If you’d rather use a cat treat dispenser to motivate your code monkeys, then check out this hack.