A Spark Gap Transmitter, Characterized

April 7, 2024 by 31 Comments

When we think of a spark gap radio transmitter, most of us immediately imagine an early twentieth century ship’s radio room or similar. Most of us know these transmitters as the first radio systems, and from there we’ll probably also know that they were phased out when better circuits arrived, because of their wide bandwidth. So it’s rare in 2024 to find anyone characterizing a spark gap transmitter, as [Baltic Lab] has.

The circuit is simple enough, a high voltage passes through an RC network to a spark gap, the other side of which is a tuned circuit. The RC network and the spark gap form a simple low frequency relaxation oscillator, with the C being charged until the spark gap triggers, forcing the subsequent discharge of the capacitor and causing the spark to extinguish and the cycle to repeat. The resulting chain of high voltage pulses repeatedly energizes the tuned circuit, with each pulse causing a damped oscillation at its resonant frequency. The resulting RF signal is a crude AM tone which can be received fairly simply.

The mathematics behind it all is pretty interesting, revealing both the cause of the bandwidth spread in the low Q factor of the tuned circuit, and the presence of a large spurious frequency spike on an interaction with the capacitor in the RC circuit. It’s all in the video below the break, and we have to admit, it taught us something about radio we didn’t know.

Meanwhile spark gaps weren’t the only early radio transmitter technology. How about an alternator?

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Hackaday Links: April 7, 2024

April 7, 2024 by 12 Comments

Folks with a bit of knowledge about network security commonly use virtual private networks (VPNs) when out and about. Whether you’re connecting to public WiFi or somebody passes you a questionable Ethernet cable at a hacker con, it’s nice to have a secure endpoint to tunnel all of your traffic. As a secondary bonus, connecting through a VPN can obscure your physical location. It’s that second feature that has a bunch of people jumping on the VPN bandwagon as they try to dodge the recent porn age checks that have gone into effect in a number of states. According to a recent article in PopSci, one particular VPN provider saw a 275% jump in demand on the same day that PornHub cut off access to users in Texas. While the debate over underage users accessing adult content is far outside of our wheelhouse, anything that gets more users connecting to the Internet via encrypted means is arguably a net positive.

If you wanted somebody from the Geek Squad to set up that VPN so you can get back on PornHub to work securely from the local coffee shop, you might be out of luck. Reports have been coming in that Best Buy’s mobile nerd division is seeing sweeping layoffs. Geeks were told to stay home on Tuesday and await a call from corporate, at which point many got the surprising news that they no longer had a job. The /r/GeekSquad subreddit has been a rallying point for staff who got the axe, with the user [jaym026] posting what we assume is an AI-generated inspirational speech from Optimus Prime. Of course, it sucks for anyone to lose their job, especially with the way things are these days. Still, we’re willing to bet almost none of those affected will look back on the day they were let go from an increasingly irrelevant brick-and-mortar electronics store as a low point in their professional careers.

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Emergency DIP Pin Repair For Anyone

April 7, 2024 by 20 Comments

Who has not at some point in their lives experienced the horror of a pin on a DIP package breaking off? It’s generally game over, but what if you don’t have another chip handy to substitute? It’s time to carefully grind away some of the epoxy and solder on a new pin, as [Zafer Yildiz] has done in the video below the break.

The technique relies on the pins continuing horizontally inside the package , such that they provide a flat surface. He’s grinding with the disk on a rotary tool, we have to say we’d use one of the more delicate grinding heads for something more akin to a miniature die grinder.

Once the flat metal surface is exposed, the chip is placed in a socket, and a new pin is cut from the leg of a TO-220 power device. This is carefully bent over, inserted in the socket, and soldered into place. The whole socket and chip arrangement is then used in place of the chip, making for something a little bulky but one infinitely preferable to having to junk the device.

There are many useful skills to be learned when it comes to reworking, and we’ve covered a few in our time. Most recently we saw a guide to lifting SMD pins.

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Squishy Miter Saw Shroud Spares You The Sneezy Bits

April 7, 2024 by 8 Comments

Let’s be honest. When it comes to operating miter saws, these tools kick dust out the back like a spray paint can. Most of us have accepted this quirk as-is, but not [Inspire Woodcraft] who’s on a mission to achieve near perfect dust collection. And he nearly has it. With a budget dust collection setup, he’s able to eliminate over 90% of the dust from his cuts, and others who’ve adopted his setup can vouch for his results.

The solution comes in two pieces. First, he focuses on creating a new dust shroud or “boot” for collecting dust through the vacuum hookup on the back of the saw. What’s key here is that this dust boot is made from squishy silicone, enabling it to flare outwards and spread out as the saw travels downward into the material. It’s clear that [Inspire Woodcraft] has gone through dozens of material and shape iterations, but the result is sturdy enough to stay open with the vacuum running through the back hose attachment.

With the dust nearly perfectly funneled from the back, the second tweak focuses on rerouting stray dust away from the table and directly into this boot. [Inspire Woodcraft] later noticed that dust collection from the bottom of his miter saw simply didn’t exist, so dust would accumulate at his feet.

His solution? To create a second shroud that fits under the throat plate that takes sawdust once destined for the ground and ejects it backwards and straight into the dust collection boot.

Altogether, this setup solves a long-existing problem with a handful of commodity parts and a few 3D prints. [Inspire Woodcraft] has also chronicled his journey in such detail where you too could recreate his solution from the video. But if you’re feeling lazy, and you’re lucky enough to own the same Dewalt DW716 or DWS716 model miter saws, you can simply snag a kit from his website.

If all this talk of miter saws has your reaching for a screwdriver to see what modified mayhem you can unleash with yours, look no further than this LED hack that adds a shadow line to your cuts.

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The Easy Way To Make A Smart Appliance

April 7, 2024 by 32 Comments

It seems that finding an appliance without some WiFi connectivity and an app to load your laundry data into the cloud is an increasingly difficult thing to do in the 2020s. Many of us resolutely refuse to connect these smart appliances to the Internet, but not because we don’t see the appeal — we just want to do it on our own terms.

[Terence Eden] did just this with his rice cooker, using a surprisingly straightforward approach. He simply connected it to the mains via an energy monitoring smart plug, and that was the hardware part, done. Of course, were it that simple we probably wouldn’t be featuring this here, as the meat of this project lies in connecting it to his smart home systems and getting something useful from it.

He’s using Home Assistant, and after a bit of messing about had it part of his home automation system. Then it was time for Appliance Status Monitor, which allowed him to easily have the rice cooker send him a notification once it has done its thing by monitoring the power it was using. All online, part of a smart home, and not a byte of his data captured and sold to anyone!

This isn’t the first home automation project we’ve brought you from this source.

Comparing Desoldering Tools

April 7, 2024 by 26 Comments

[Lee] has a Hakko FR301 desoldering gun and a Duratool knockoff. He freely admits that the Hakko is probably better, but he wonders if it’s good enough to justify being four times as expensive. He shows both of them off in a recent video that you can see below.

Often, desoldering doesn’t get as much attention as soldering, but for repairs or if you make mistakes —  and who doesn’t — it is an essential skill. Many of the differences will be either good or bad, depending on your personal preference. For example, the Hakko is an all-in-one unit, so it doesn’t have a bulky box to sit on your bench. However, that also means the Hakko is larger and heavier. It also lacks controls and indicators the other unit has on the base station box.

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Jpegli: Google’s Better JPEG And Possible Death Knell For WebP

April 7, 2024 by 56 Comments

Along with the rise of the modern World Wide Web came the introduction of the JPEG image compression standard in 1992, allowing for high-quality images to be shared without requiring the download of a many-MB bitmap file. Since then a number of JPEG replacements have come and gone – including JPEG 2000 – but now Google reckons that it can improve JPEG with Jpegli, a new encoder and decoder library that promises to be highly compatible with JPEG.

To be fair, it’s only the most recent improvement to JPEG, with JPEG XT being introduced in 2015 and JPEG XL in 2021 to mostly deafening silence, right along that other, better new image format people already forgot about: AVIF. As Google mentions in their blog post, Jpegli uses heuristics developed for JPEG XL, making it more of a JPEG XL successor (or improvement). Compared to JPEG it offers a higher compression ratio, 10+-bit support which should reduce issues like banding. Jpegli images are said to be compatible with existing JPEG decoders, much like JPEG XT and XL images.

Based on the benchmarks from 2012 by [Blobfolio] between JPEG XL, AVIF and WebP, it would seem that if Jpegli incorporates advancements from AVIF while maintaining compatibility with JPEG decoders out there, it might be a worthy replacement of AVIF and WebP, while giving JPEG a shot in the arm for the next thirty-odd years of dominating the WWW and beyond.