Multicolored Ethernet Controlled LED Lamp

March 31, 2006 by 18 Comments

led lamp

[Laurens Tromp] stumbled upon this LED lamp project while looking for a datasheet. The lamp has two heads with 252 LEDs each. The individual heads have equal number of red, blue, green, yellow and white LEDs. At the base of the lamp is a touch pad that has a virtual slider for each individual color’s intensity. The heads can be controlled separately or together. The lamp can also be operated over ethernet since its controller is a RabbitCore RCM2200. The only answer I can’t seem to find in the extensive documentation is how much this milled aluminum monstrosity weighs: 110 pounds.

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Power Over Ethernet

May 21, 2005 by 15 Comments

Power Over Ethernet

Power over ethernet lets you add a DC voltage source to the unused pairs in your ethernet cable. This power can be used to power devices that are poe compatible by just plugging the cable into them. Other devices can be powered by using a “tap” to break the DC pairs back out of the cable. POE is a good choice for powering devices in remote locations. A router can be placed on a roof right next to its high-gain antenna, reducing signal loss, without having to run a separate AC line. Plugging the DC “injector” into a UPS will keep dedicated VOIP phones functioning during a power outage. Terry Schmidt has written a nice guide covering the theory behind scratch building poe injectors and taps. It also has photos and descriptions of other peoples projects along with tips on how to keep from turning your router into a pile of plastic goo.

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Raspberry Pi Becomes Secure VPN Router

September 16, 2024 by 20 Comments

OpenWRT is a powerful piece of open-source software that can turn plenty of computers into highly configurable and capable routers. That amount of versatility comes at a cost, though; OpenWRT can be difficult to configure outside of the most generic use cases. [Paul] generally agrees with this sentiment and his latest project seeks to solve a single use case for routing network traffic, with a Raspberry Pi configured to act as a secure VPN-enabled router configurable with a smartphone.

The project is called PiFi and, while it’s a much more straightforward piece of software to configure, at its core it is still running OpenWRT. The smartphone app allows most users to abstract away most of the things about OpenWRT that can be tricky while power users can still get under the hood if they need to. There’s built-in support for Wireguard-based VPNs as well which will automatically route all traffic through your VPN of choice. And, since no Pi router is complete without some amount of ad blocking, this router can also take care of removing most ads as well in a similar way that the popular Pi-hole does. More details can be found on the project’s GitHub page.

This router has a few other tricks up its sleeve as well. There’s network-attached storage (NAS) built in , with the ability to use the free space on the Pi’s microSD card or a USB flash drive. It also has support for Ethernet and AC1300 wireless adapters which generally have much higher speeds than the built-in WiFi on a Raspberry Pi. It would be a great way to build a guest network, a secure WiFi hotspot when traveling, or possibly even as a home router provided that the home isn’t too big or the limited coverage problem can be solved in some other way. If you’re looking for something that packs a little more punch for your home, take a look at this guide to building a pfSense router from the ground up.

Pulling Apart An Old Satellite Truck Tracker

September 13, 2024 by 9 Comments

Sometimes there’s nothing more rewarding than pulling apart an old piece of hardware of mysterious origin. [saveitforparts] does just that, and recently came across a curious satellite system from a surplus store. What else could he do, other than tear it down and try to get it humming? 

The device appeared to be satellite communication device for a tracking unit of some sort, complete with a long, thick proprietary cable. That led to a junction box with a serial port and an RJ45 port, along with some other interfaces. Disassembly of the unit revealed it contained a great deal of smarts onboard, including some kind of single-board computer. Comms-wise, it featured a cellular GPRS interface as well as an Orbcomm satellite modem. It also packed in GPS, WiFi, Xbee, Ethernet, and serial interfaces. It ultimately turned out to be a Digi ConnectPort X5 device, used as a satellite tracking system for commercial trucks.

What’s cool is that the video doesn’t just cover pulling it apart. It also dives into communicating with the unit. [saveitforparts] was able to power it up and, using the manufacturer’s software, actually talk to the device. He even found the web interface and tested the satellite modem.

Ultimately, this is the kind of obscure industry hardware that most of us would never come into contact with during our regular lives. It’s neat when these things show up on the secondary market so hackers can pull them apart and see what makes them tick. Video after the break.

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Where Do You Connect The Shield?

September 13, 2024 by 23 Comments

When it comes to polarizing and confusing questions in electronics, wiring up shields is on the top-10 list when sorted by popularity. It’s a question most of us need to figure out at some point – when you place a USB socket symbol on your schematic, where do you wire up the SHIELD and MP pins?

Once you look it up, you will find Eevblog forum threads with dozens of conflicting replies, Stackexchange posts with seven different responses plus a few downvoted ones, none of them accepted, and if you try to consult the literature, the answer will invariably be “it depends”.

I’m not a connector-ground expert, I just do a fair bit of both reading and hacking. Still, I’ve been trying to figure out this debate, for a couple years now, re-reading the forum posts each time I started a new schematic with a yet-unfamiliar connector. Now, of course, coming to this question with my own bias, here’s a summary you can fall back on.

Consumer Ports

Putting HDMI on your board? First of all, good luck. Then, consider – do you have a reason to avoid connecting the shield? If not, certainly connect the shield to ground, use jumpers if that’s what makes you comfortable, though there’s a good argument that you should just connect directly, too. The reason is simple: a fair few HDMI cables omit GND pin connections, fully relying on the shield for return currents. When your HDMI connection misfires, you don’t want to be debugging your HDMI transmitter settings when the actual No Signal problem, as unintuitive as it sounds, will be simply your shield not being grounded – like BeagleBone and Odroid didn’t in the early days. By the way, is a DVI-D to HDMI adapter not working for you? Well, it might just be that it’s built in a cheap way and doesn’t connect the shields of the two sockets together – which is fixable.

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DEC’s LAN Bridge 100: The Invention Of The Network Bridge

August 27, 2024 by 13 Comments

DEC’s LAN Bridge 100 was a major milestone in the history of Ethernet which made it a viable option for the ever-growing LANs of yesteryear and today. Its history is also the topic of a recent video by [The Serial Port], in which [Mark] covers the development history of this device. We previously covered the LANBridge 100 Ethernet bridge and what it meant as Ethernet saw itself forced to scale from a shared medium (ether) to a star topology featuring network bridges and switches.

Featured in the video is also an interview with [John Reed], a field service network technician who worked at DEC from 1980 to 1998. He demonstrates what the world was like with early Ethernet, with thicknet coax (10BASE5) requiring a rather enjoyable way to crimp on connectors. Even with the relatively sluggish 10 Mbit of thicknet Ethernet, adding an Ethernet store and forward bridge in between two of these networks required significant amounts of processing power due to the sheer number of packets, but the beefy Motorola 68k CPU was up to the task.

To prevent issues with loops in the network, the spanning tree algorithm was developed and implemented, forming the foundations of the modern-day Ethernet LANs, as demonstrated by the basic LAN Bridge 100 unit that [Mark] fires up and which works fine in a modern-day LAN after its start-up procedure. Even if today’s Ethernet bridges and switches got smarter and more powerful, it all started with that first LAN Bridge.

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Running Stock MS-DOS On A Modern ThinkPad

August 22, 2024 by 32 Comments

It might seem like the days of MS-DOS were a lifetime ago because…well, they basically were. Version 6.22 of the venerable operating system, the last standalone release, came out back in 1994. That makes even the most recent version officially 30 years old. A lot has changed in the computing world since that time, so naturally trying to run such an ancient OS on even a half-way modern machine would be a waste of time. Right?

As it turns out, getting MS-DOS 6.22 running on a modern computer isn’t nearly as hard as you’d think. In fact, it works pretty much perfectly. Assuming, that is, you pick the right machine. [Yeo Kheng Meng] recently wrote in to share his experiments with running the final DOS release on his Intel-powered ThinkPad X13 from 2020, and the results are surprising to say the least.

To be clear, we’re not talking about some patched version of DOS here. There’s no emulator at work either. Granted [Yeo] did embrace a few modern conveniences, such as using a USB floppy drive emulator to load the disk images instead of fiddling with actual floppies, and installing DOS onto an external drive so as not to clobber his actual OS on the internal NVME drive. But other than that, the installation of DOS on the ThinkPad went along just as it would have in the 1990s.

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