usb

642 Articles

Three Computers, One Keyboard With USB Triplexer

November 4, 2022 by 25 Comments

Many of us will have the problem of several computers on the same desk, and to avoid clutter we’ll use a KVM switch to share the peripherals. [The Turbanned Engineer] has an interesting solution to this problem in the form of a USB triplexer. It’s a device that routes USB data lines depending upon which of its connections is powered up.

The circuit is simple enough: a CMOS analogue multiplexer does the routing, and a set of opto-couplers do the selecting based on the power inputs. A set of USB A sockets connect to the computer, and a USB B socket connects to the peripheral.

We’re not entirely sure whether an analogue multiplexer chip would be good for the higher-speed USB data rates, but since keyboards and mice talk at the slowest data rates, we think he’ll get away with it. Either way making a USB switch however basic with such mundane components has something of the hack about it. What he does with the display we’re not so sure about, but at least his keyboard and mouse woes are dealt with.

Other similar switches we’ve featured have been somewhat more basic.

An Open-Source HDMI Capture Card

October 14, 2022 by 37 Comments

[YuzukiHD] has provided files for anyone that wishes to build their own HDMI capture card at home. The design is known as the Yuzuki Loop Out HDMI Capture Card PRO, or YuzukiLOHCC PRO for short.

The build is based on the MS2130, a HD video and audio capture chip that’s compatible with USB 3.2 Gen 1. We’re pretty sure that’s now called USB 3.2 Gen 1×1, and that standard is capable of transfers at up to 5 Gbps. Thus, the chip can support HDMI at up to 4K resolution at 60 Hz depending on the exact signals being passed down the line. It’s compatible with YUV422 & MJPEG modes and can be used with software like OBS Studio and FFmpeg. The board itself is relatively simple. It features an HDMI In port, an HDMI Out port, and a USB-C port for hooking up to a computer for capture.

HDMI capture cards can be expensive and fussy things, so you may find it pays to roll your own. Plus, being open sourced under the CERN Open Hardware License V2 means that you can make changes to suit your own use case if you so desire.

We’ve seen some other hilarious video capture tricks over the years, such as a convoluted rig that uses a SNES to turn a Game Boy Camera into a usable webcam. If you’ve got any such madcap hacks brewing up in your lab, be sure to let us know!

Custom Macro Pad Helps Deliver Winning Formulas

October 5, 2022 by 18 Comments

For those of us with science and engineering backgrounds, opening the character map or memorizing the Unicode shortcuts for various symbols is a tedious but familiar part of writing reports or presentations. [Magne Lauritzen] thought there had to be a better way and developed the Mathboard.

With more than 80 “of the most commonly used mathematical operators” and the entire Greek alphabet, the Mathboard could prove very useful to a wide number of disciplines. Hardware-wise, the Mathboard is a 4×4 macro pad, but the special sauce is in the key set implementation firmware. While the most straightforward approach would be to pick 16 or 32 symbols for the board, [Magne] felt that didn’t do the wide range of Unicode symbols justice. By implementing a system of columns and layers, he was able to get 6+ symbols per key, giving a much greater breadth of symbols than just 16 keys and a shift layer. The symbols with a dot next to them unlock variants of that symbol by double or triple-tapping the key. For instance, a lower or capital case of a Greek letter.

The Mathboard currently works in Microsoft Office’s equation editor and as a plain-text Unicode board. [Magne] is currently working on LaTeX support and hopes to add Open Office support in the future. This device was an honorable mention in our Odd Inputs and Peculiar Peripherals Contest. If you’d like to see another interesting math-themed board, check out the one on the MCM/70 from 1974.

ADSL Router As Effects Pedal

September 8, 2022 by 11 Comments

Moore’s law might not be as immutable as we once though thought it was, as chip makers struggle to fit more and more transistors on a given area of silicon. But over the past few decades it’s been surprisingly consistent, with a lot of knock-on effects. As computers get faster, everything else related to them gets faster as well, and the junk drawer tends to fill quickly with various computer peripherals and parts that might be working fine, but just can’t keep up the pace. [Bonsembiante] had an old ADSL router that was well obsolete as a result of these changing times, but instead of tossing it, he turned it into a guitar effects pedal.

The principle behind this build is that the router is essentially a Linux machine, complete with ALSA support. Of course this means flashing a custom firmware which is not the most straightforward task, but once the sound support was added to the device, it was able to interface with a USB sound card. An additional C++ program was created which handles the actual audio received from the guitar and sound card. For this demo, [Bonsembiante] programmed a ring buffer and feeds it back into the output to achieve an echo effect, but presumably any effect or a number of effects could be programmed.

For anyone looking for the source code for the signal processing that the router is now performing, it is listed on a separate GitHub page. If you don’t have this specific model of router laying around in your parts bin, though, there are much more readily-available Linux machines that can get this job done instead.

Continue reading “ADSL Router As Effects Pedal” →

The Coolest 1990s Film Scanner To Work With Windows 11

September 6, 2022 by 47 Comments

Unless you happen to be a retro enthusiast, it’s fair to say that any photography you do (whether on your phone or a dedicated camera) is going to be digital. The world of photography has all but completely moved away from film, but the transition was not instantaneous. Instead there was a period of about ten years from the mid-90s when film and digital existed side-by-side in some form. A profitable sideline for photography shops was providing scans of film, and there were a series of high-end scanners aimed at that market.

[Kai Kaufman] shares the experience of making one of these work with a modern Windows version, and it’s interesting both because of the scanner itself and the epic tale of software detective work required to bring it up to date. The scanner in question is a Pakon F135, the product of a Kodak acquisition, and an all-in-one device that simply spools in a roll of film and does all the hard work of identifying the frames, cropping the images, and reading any other data from the film.

You may never have seen one of these machines, but if you ever had your photos on a CD as well as printed back in the day you’ve probably had its output. The problem in 2022 is that these machines have drivers which only work with relatively ancient 32-bit Windows versions, so most of the write-up involves some significant detective work into the drivers.

Not every reader will be an expert on Windows driver de-compilation, but perhaps the most interesting pieces of the puzzle come from his detective work in finding the origin of some components. Example code from Microsoft and from a chip design company both make the job much easier, and the final result is a fully functioning 64-bit driver for the device. Not many people will have a Pakon film scanner, but for those who do it seems life may just have become a bit easier.

Thanks [adilosa] for the tip!

The Ease Of Wireless Charging, Without The Wait

September 2, 2022 by 14 Comments

Historically, there have been a few cases of useful wireless power transmission over great distances, like a team at MIT that was able to light up a 60 W bulb at several meters, and of course Nikola Tesla had grand dreams of drawing energy from the atmosphere. But for most of us wireless power is limited to small, short-range devices like cellphone chargers. While it’s not a lot of work to plug in a phone when it needs a charge, even this small task can be automated.

This build begins with a 3D printed cradle for the smartphone to sit in. When the device detects that the phone has been placed in the cradle, it uses a linear actuator to drive a custom-built charging cable into the phone’s USB port. Similarly, when the phone is lifted from the cradle the cable is automatically removed. It appears that there is some play in the phone’s position that lets the charger be plugged in smoothly, and the project’s creator [Larpushka] points out that the linear actuator is not particularly strong so we don’t imagine the risk of damage is very high.

While wireless charging still may have the edge when it comes to keeping debris out of the port, we still really enjoy a project like this that seems to be done for its own sake. There are some improvements that [Larpushka] plans to make, but for now we’re delighted by this build. For anyone looking to add true wireless charging to any phone that doesn’t have it, though, it’s not too difficult to accomplish either.

USB-C Charging Mod Brings In The Juice

August 16, 2022 by 13 Comments

By now we’re well under way with the consolidation of low-voltage power supplies under the USB-C standard, and the small reversible connector has become the de facto way to squirt some volts into our projects. But for all this standardization there are still a few places where the harmony of a unified connector breaks down, and things don’t work quite the way they are supposed to. One such case has occupied [James Ide] — devices which will accept power from a USB-A to USB-C cable, but not from a USB-C to USB-C one. His solution? A small flexible PCB upgrade.

The problem lies with how different power supplies and peripherals identify each other, and quite likely in device manufacturers skimping on a few components here and there. A compliant USB-C power supply expects to see pull-down resistors on the data lines, and will thus refuse to serve power to devices that don’t possess them. Meanwhile the USB-A supply will quite happily serve juice without such checks, which is what the manufacturer is relying on. The solution is a tiny flexible PCB with the resistors, designed to be retrofitted behind a USB-C socket. On one hand it’s probably one of the simplest circuits we’ve ever shown you, and on the other it’s a cleverly designed solution to the issue at hand.

If the nitty-gritty of USB-C interests you, then we’ve taken a much closer look in the past.

Thanks to [Andrea] for the tip.