Misc Hacks

4178 Articles

IPhone Becomes A Bluetooth Keyboard And Mouse

February 1, 2026 by 20 Comments

Sometimes you need to use a computer and you don’t have a spare keyboard and mouse on hand. [KoStard] figured an iPhone could serve as a passable replacement interface device. To that end, he built an adapter to let the phone act as a wireless keyboard and mouse on just about any modern machine.

To achieve this, [KoStard] grabbed an ESP32-S3 development board, and programmed it to act as a USB HID device to any machine attached over USB. It then listens out for Bluetooth LE communications from an iPhone equipped with the companion app. The app provides an on-screen keyboard on the iPhone that covers everything including special keys, symbols, and punctuation. You can also take advantage of the iPhone’s quality capacitive touchscreen, which emulates a nicely-responsive  trackpad, with two-finger taps used for right clicking and two-finger drags for scroll. Latency is nice and low courtesy of the direct Bluetooth LE connection.

It’s a nifty build that is particularly useful in oddball situations where you might want a keyboard and mouse. For example, [KoStard] notes it’s a great way to control a Smart TV without having to do ugly slow “typing” on an infrared remote. We’ve seen his work before, too—previously building an adapter to provide Bluetooth capability to any old USB keyboard. Video after the break.

Continue reading “IPhone Becomes A Bluetooth Keyboard And Mouse” →

The Fancy Payment Cards Of Taiwan

January 28, 2026 by 23 Comments

If you’re an old-schooler, you might still go to the local bar and pay for a beer with cash. You could even try and pay with a cheque, though the pen-and-paper method has mostly fallen out of favor these days. But if you’re a little more modern, you might use a tap-to-pay feature on a credit or debit card.

In Taiwan, though, there’s another unique way to pay. The island nation has a whole ecosystem of bespoke payment cards, and you can even get one that looks like a floppy disk!

Continue reading “The Fancy Payment Cards Of Taiwan” →

How HP Calculators Communicate Over Infrared

January 27, 2026 by 10 Comments

For most people, calculators are cheap and simple devices used for little more than addition and the odd multiplication job. However, when you get into scientific and graphical calculators, the feature sets get a lot more interesting. For example, [Ready? Z80] has this excellent explainer on how HP’s older calculators handle infrared communications.

The video focuses on the HP 27S Scientific Calculator, which [Ready? Z80] found in an op-shop for just $5. Introduced in 1988, the HP-27S had the ability to dump screen data over an infrared link to a thermal printer to produce paper records of mundane high-school calculations or important engineering math. In the video, [Ready? Z80] explains the communication method with the aid of Hewlett-Packard’s own journal publication from October 1987, which lays out of the details of “the REDEYE Protocol.” Edgy stuff. It’s pretty straightforward to understand, with the calculator sending out bursts of data in six to eight pulses at a time, modulated onto a 32.768KHz square wave as is the norm. [Ready? Z80] then goes a step further, whipping up custom hardware to receive the signal and display the resulting data on a serial terminal. This is achieved with a TEC-1G single-board computer, based on the Z80 CPU, because that’s how [Ready? Z80] does things.

We’ve seen other great stuff from this channel before, too. For example, if you’ve ever wanted to multitask on the Z80, it’s entirely possible with the right techniques. Video after the break.

Continue reading “How HP Calculators Communicate Over Infrared” →

Smoothie Bikes Turned Into Game Controllers

January 27, 2026 by 9 Comments

Smoothie bikes are a great way to make a nutritious beverage while getting a workout at the same time. [Tony Goacher] was approached by a local college, though, which had a problem with this technology. Namely, that students were using them and leaving them filthy. They posed a simple question—could these bikes become something else?

[Tony’s] solution was simple—the bikes would be turned into game controllers. This was easily achieved by fitting a bi-color disc into the blender assembly. As the wheel on the bike turns, it spins up the blender, with the disc inside. An ESP32 microcontroller paired with a light sensor is then able to count pulses as the disc spins, getting a readout of the blender’s current RPM. Working backwards, this can then be calculated out into the bike’s simulated road speed and used to play a basic game on an attached Raspberry Pi. Notably, the rig is setup such that the Raspberry Pi and one bike connect to an access point hosted by the other bike.  This is helpful, because it means neither bike has too many dangling cables that could get caught up in a wheel or chain.

We’ve seen many amusing game peripherals over the years, from salad spinners to turntables. Video after the break.

Continue reading “Smoothie Bikes Turned Into Game Controllers” →

Building A Clamshell Writer Deck

October 31, 2025 by 10 Comments

Most of us do our writing on computers these days, but the modern computing environment does present a lot of distractions. That’s let to the concept of the writer deck, a simplified device intended more specifically for word processing tasks. [Ashtf] has built a great example of the form with a modified version of the PocketMage device.

The PocketMage is a clamshell PDA device that [Ashtf] has been working on for some time. It’s powered by an ESP32, hooked up to a nice e-ink display. In its basic form, it’s not the ideal device for doing serious writing work, mostly because of its tiny keyboard. However, [Ashtf] has since added external keyboard support, which completely changes the game. With the use of a small USB C to USB A adapter, you can hook up any conventional USB keyboard that you like to best attain your maximum typing speed.

The result is a compact, simple device that lets you type away without distractions. If your latest fanfic isn’t coming along quickly enough because you keep losing focus to social media, perhaps this is a route you might like to go. [Ashtf] also included Markdown support so you can create richer documents on the device while operating in what is still fundamentally a text-only environment.

It’s neat to build custom devices that suit your own personal productivity needs. If you dig the PocketMage, you might like to check out the design files on Github. We’ve featured some other fun writer decks before, too. Video after the break.

Continue reading “Building A Clamshell Writer Deck” →

Hacking Together An Expensive-Sounding Microphone At Home

October 30, 2025 by 11 Comments

When it comes to microphones, [Roan] has expensive tastes. He fancies the famous Telefunken U-47, but doesn’t quite have the five-figure budget to afford a real one. Thus, he set about getting as close as he possibly could with a build of his own.

[Roan] was inspired by [Jim Lill], who is notable for demonstrating that the capsule used in a mic has probably the greatest effect on its sound overall compared to trivialities like the housing or the grille. Thus, [Roan’s] build is based around a 3U Audio M7 capsule. It’s a large diaphragm condenser capsule that is well regarded for its beautiful sound, and can be had for just a few hundred dollars. [Roan] then purchased a big metal lookalike mic housing that would hold the capsule and all the necessary electronics to make it work. The electronics itself would be harvested from an old ADK microphone, with some challenges faced due to its sturdy construction. When the tube-based amplifier circuit was zip-tied into its new housing along with the fancy mic capsule, everything worked! Things worked even better when [Roan] realized an error in wiring and got the backplate voltage going where it was supposed to go. Some further tweaks to the tube and capacitors further helped dial in the sound.

If you’ve got an old mic you can scrap for parts and a new capsule you’re dying to use, you might pursue a build like [Roan’s]. Or, you could go wilder and try building your own ribbon mic with a gum wrapper. Video after the break.

Continue reading “Hacking Together An Expensive-Sounding Microphone At Home” →

100-Year Old Wagon Wheel Becomes Dynamometer

October 30, 2025 by 8 Comments

If you want to dyno test your tuner car, you can probably find a couple of good facilities in any  nearby major city. If you want to do similar testing at a smaller scale, though, you might find it’s easier to build your own rig, like [Lou] did.

[Lou’s] dynamometer is every bit a DIY project, relying on a 100-year-old wagon wheel as the flywheel installed in a simple frame cobbled together from 6×6 timber beams. As you might imagine, a rusty old wagon wheel probably wouldn’t be in great condition, and that was entirely true here. [Lou] put in the work to balance it up with some added weights, before measuring its inertia with a simple falling weight test. The wheel is driven via a chain with a 7:1 gear reduction to avoid spinning it too quickly. Logging the data is a unit from BlackBoxDyno, which uses hall effect sensors to measure engine RPM and flywheel RPM. With this data and a simple calibration, it’s possible to calculate the torque and horsepower of a small engine hooked up to the flywheel.

Few of us are bench testing our lawnmowers for the ultimate performance, but if you are, a build like this could really come in handy. We’ve seen other dyno builds before, too. Video after the break.

Continue reading “100-Year Old Wagon Wheel Becomes Dynamometer” →