A Dim Bulb Tester Is For Testing Other Equipment, Not Bulbs

January 18, 2024 by 26 Comments

If you’re testing old stereo equipment, a dim bulb tester can really come in handy. It’s not for testing bulbs, though, it’s a tester that uses a dim bulb to test other things. [Nicholas Morganti] explains it all in his guide to making your own example of such a tool. Just be wary — you need to know what you’re doing with mains voltages to do this safely!

The dim bulb is a deceptively simple tool that nonetheless often proves useful in diagnostics. It normally just consists of a bulb connected in series with the equipment under test. The bulb is intended to be a similar wattage to the power draw of the equipment itself. Take for example, an amplifier. If the bulb glows brightly when the amp is under no load, it suggests there may be a short circuit somewhere. That’s because the glowing bulb indicates that plenty of current is being drawn under a condition when very little should be flowing. The bulb protects the equipment by essentially acting as a bit of a current limiting device. It’s a soft-start tool for a piece of vulnerable equipment.

Building one is usually as simple as gathering an enclosure, a plug receptacle, a bulb socket, and some other ancillary parts to lace everything together. [Nicholas] explains it all with clear diagrams and tells you how to follow along. It’s easy enough, but you really need to know what you’re doing to use one safely, as mains voltages are involved.

It’s a great tool to have if you’re getting into amplifier repair or similar work on old gear. If you’ve been whipping up your own must-have tools, don’t hesitate to let us know!

Android-Powered Rigol Scopes Go Wireless

January 18, 2024 by 9 Comments

The Rigol DHO800 and DHO900 series use Android underneath, and as you might expect, this makes them easier to hack. A case in point: [VoltLog] demonstrates that you can add WiFi to the scope using a cheap USB WiFi adapter. This might seem like a no-brainer on the surface, but because the software doesn’t know about WiFi, there are a few minor hoops to jump through.

The first issue is that you need a WiFi adapter the built-in OS already knows how to handle. The community has identified at least one RTL chipset that works and it happens to be in the TP-Link TL-WN725N. These are old 2.4 GHz only units, so they are widely available for $10 or less.

But even with the correct hardware, the scope doesn’t have any menus to configure the WiFi interface. To solve that, you need to temporarily use a USB hub and a USB keyboard. Once you have everything plugged in, you can use the Super + N keyboard shortcut to open up the Android notification bar, which is normally hidden. Once you’ve setup the network connection, you won’t need the keyboard anymore.

Or maybe not — it turns out the keyboard does allow you to change a few other things. For example, [VoltLog] used it to increase the screen brightness more than the default maximum setting.

The only other issue appears to be that the scope shows it is disconnected even when connected to WiFi. That doesn’t seem to impact operation, though. Of course, you could use a WiFi to Ethernet bridge or even an old router, but now you have a cable, a box, and another power cord to deal with. This solution is neat and clean. You bet we’ve already ordered a TP-Link adapter!

WiFi scopes are nothing new. We suspect Rigol didn’t want to worry about interference and regulatory acceptance, but who knows? Besides, it is fun to add WiFi to wired devices.

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Neon Watch Glows Rather Nicely, Tells Time

January 17, 2024 by 12 Comments

It wasn’t long after the development of the LED that LED watches became available. They were prized for their clear light output and low power draw. Neon bulbs, on the other hand, are thirsty for current and often warm or even hot in operation. And yet, [Lucas] found a way to build them into a sweet watch that actually does the job. Nice, right?

The design uses a simple trick to avoid killing the batteries with excessive power draw. The neon lamps are only activated when the user waves a hand above the watch, at which point the lamps light to display the time. Reading the time is  a little fiddly, but understandable with the aid of this PDF diagram. Basically, the two electrodes of each neon lamp are driven independently. This gives each of the four lamps three possible states: with the first electrode lit, the second electrode lit, or both lit. Four lamps multiplied by three states equals 12—so the watch can display the hour quite easily. As for minutes, a similar scheme is used with some modifications for clarity. Setting the time is via a light sensor on the watch which picks up flashes from a computer screen.

It reminds us of a time when we once thought nixie tubes were too power hungry for a wristwatch build… until the hackers of the world proved us wrong. Video after the break.

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Modeling Network Latency

January 17, 2024 by 6 Comments

The selfhosting community is an interesting and useful part of the Internet dedicated to removing one’s own services and data from the cloud and hosting it on their own servers, often on hardware that can be physically touched. With that kind of network usage, it’s not uncommon for people to build their own routers, firewalls, and other network support systems from the ground up. And, if you go deep enough, maybe even a home lab dedicated to testing and improving the network’s various layers. This piece of software helps simulate network latency to more accurately assess quality of service, performance, and the optimization of one one’s own networks.

The tool, called Speedbump, allows a network administer to quickly build a test network where characteristics of the network such as base latency and wave shape and size can be set up. From there, a TCP proxy sends the network traffic through the virtual network, adding in a set amount of delay to anything traveling on the network. It can be installed (or built from source) on an existing installation or used from within a Docker terminal, so there are plenty of options depending on preference. It’s also available as a library for any programs written in Go.

While this certainly has applications for home labs where self-hosting services is done at a high level, this could have professional applications as well. For troubleshooting simpler network issues we’d always recommend this tool which allows a more comprehensive network test than the standard “ping” command, and if you haven’t heard of selfhosting before it’s probably time to read this primer on it and build a hobby web server from scratch.

FLOSS Weekly Episode 766: WebRTC — The Hack That Connects Everyone To Everything

January 17, 2024 by 7 Comments

This week Jonathan Bennett and Dan Lynch talk with Sean DuBois, WebRTC wizard, all about the crazy feats the Pion Go server is capable of, how WebRTC is about to change OBS, and what it looks like to build a successful Open Source Career.

WebRTC is for more than video. The TOR Snowflake project uses Pion to sneak TOR traffic through firewalls even with Deep Packet Inspection (DPI) at play. Since nobody wants to block web conferencing, TOR and even Wireguard can use this to slip though.

Sean is also working on some game-changing patches for OBS Studio, including WHEP support to go along with the newly introduced WHIP feature. This enables direct connections to another OBS client, as well as connection to another WebRTC client like vdo.ninja without running an embedded browser to make it work.

And then there’s WebRTC For The Curious, a free CC0 e-book all about the nuts and bolts of WebRTC. And Broadcast Box, a ready-to-run WebRTC one-to-many broadcasting solution that lets you run your own streaming service. You can connect with Sean at the Real-time Broadcast Discord server for information about all of the projects listed here and more!

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Blastoise Humidifier Shows Us You Don’t Need A 3D Printer If You’re This Good With A 3D Pen

January 17, 2024 by 14 Comments

[3D SANAGO] is a bit of a master when it comes to using a 3D-printing pen. Their latest work involved fixing a broken humidifier and giving it a Pokemon-themed makeover. It’s an education in just what can be achieved with a tool many of us write off as a simple novelty.

The basic idea of the build was to create a Blastoise figurine that serves as a humidifier. Work starts with marking out a basic outline on a round stone. The 3D pen is then used to create a tortoise shell with the appropriate concave shape, directly on the rock. [3D SANAGO] also demonstrates how a simple plastic framework can be heated with a blowtorch and shaped around the rock as needed to generate gentle curves. Meanwhile, a simple marker pen serves as a form for creating the gun barrels on Blastoise’s back. The legs are built with a similar technique, but with expert manipulation with a blowtorch to turn them into stubby muscular forms.

The full figurine is built up in stages, with individual wireframe components assembled into a complete body. The gaps in the frame are then filled in by hand, which takes a long time; [3D SANAGO] calls it “the most boring for sure.” Plenty of post-processing is then done with various sanding tools and a bladed tip on a soldering iron. The latter is used as the melting action allows the creation of a smooth final surface. In contrast, subtractive methods like sanding would leave holes and divots that need to be filled in before painting. There’s plenty of sealing to be done before paint, too, to ensure the interior of Blastoise can hold water without leaking. Then, the internal componets are installed and the body finished to its final cartoon form. In case you’re wondering, [3D SANAGO] says that sanding took 2-3 days to get such a great result.

If you really dig it, it’s on display at [3D SANAGO’s] cafe in Daejeon. Overall, it’s amazing to see such craftsmanship with a 3D pen. A resin printer could obviously print a wonderful Blastoise of similar quality, but there’s something about watching the level of human skill in this that’s just compelling. Video after the break.

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Arduino, Virtually

January 17, 2024 by 3 Comments

While simulating an Arduino isn’t a new idea, a recent project by [LRusso] provides an open source JavaScript simulator that runs in your browser. You can try it out live or host it yourself if you prefer.

The simulator looks much like the standard IDE, so there isn’t much to learn. You can select from several targets, including a UNO R3, a MEGA 1280, a MEGA 2560, or a NANO V3. At the bottom of the screen, you’ll see the correct number of digital pins, analog pins, and the serial monitor. The code is relatively new, and we noticed that the digital and output pins seem to work only for outputs. There is no way to modify any of the values from the user interface. You can, however, enter things into the serial monitor.

You can run a canned demo that uses digital and analog output. There is also another sample that uses the serial port. Unlike some other simulators, you can’t really add much external circuitry but, for some purposes, that isn’t a problem.

If you are looking for more, there is Simulide, which is also free. Falstad can do mixed signal simulations with Arduino code. There’s also Wokwi, which we’ve covered a few times before.