Making Magnetic Tape From Scratch

October 24, 2023 by 34 Comments

The use of magnetic tape and other removable magnetic media is now on the wane, leading to scarcity in some cases where manufacture has ceased. Is it possible to produce new magnetic tape if you don’t happen to own a tape factory? [Nina Kallnina] took the effort to find out.

It’s probably one of those pieces of common knowledge, that magnetic media use iron oxides on their surface, which is the same as rust. But the reality is somewhat more complex, as there is more than one iron oxide. We follow [Nina] through this voyage of discovery in a Mastodon thread, as she tries first iron filings, the rust, and finally pure samples of the two iron oxides Fe3O4 and Fe2O3. She eventually achieves a working tape with a mixture of Fe2O3 and iron powder, though its performance doesn’t match manufactured tape. It turns out that there are two allotropes of Fe2O3, and she leaves us as she’s trying to make the one with better magnetic properties.

These results look promising, and while there is evidently a very long way to go before a home-made magnetic coating could replicate the exacting demands of for example a hard drive platter it’s evident that there is something in pursuing this path.

This may be the first time we’ve seen tape manufacture, but we’ve certainly seen extreme measures taken to rejuvenate old tapes.

Learning About Capacitors By Rolling Your Own Electrolytics

October 24, 2023 by 17 Comments

Ever wonder what’s inside an electrolytic capacitor? Many of us don’t, having had at least a partial glimpse inside after failure of the cap due to old age or crossed polarity. The rest of us will have to rely on this behind-the-scenes demo to find out what’s inside those little aluminum cans.

Perhaps unsurprisingly, it’s more aluminum, at least for the electrolytics [Denki Otaku] rolled himself at the Nippon Chemi-Con R&D labs. Interestingly, both the anode and cathode start as identical strips of aluminum foil preprocessed with proprietary solutions to remove any oils and existing oxide layers. The strips then undergo electrolytic acid etching to create pits to greatly increase their surface area. The anode strips then get anodized in a solution of ammonium adipate, an organic acid that creates a thin aluminum oxide layer on the strip. It’s this oxide layer that actually acts as the dielectric in electrolytic capacitors, not the paper separator between the anode and cathode strips.

Winding the foils together with the paper separator is pretty straightforward, but there are some neat tricks even at the non-production level demonstrated here. Attachment of lead wires to the foil is through a punch and crimp operation, and winding the paper-foil sandwich is actually quite fussy, at least when done manually. No details are given on the composition of the electrolyte other than it contains a solvent and an organic acid. [Denki] took this as an invitation to bring along his own electrolyte: a bottle of Coke. The little jelly rolls get impregnated with electrolyte under vacuum, put into aluminum cans, crimped closed, and covered with a heat-shrink sleeve. Under test, [Denki]’s hand-rolled caps performed very well. Even the Coke-filled caps more or less hit the spec on capacitance; sadly, their ESR was way out of whack compared to the conventional electrolyte.

There are plenty more details in the video below, although you’ll have to pardon the AI voiceover as it tries to decide how to say words like “anode” and “dielectric”; it’s a small price to pay for such an interesting video. It’s a much-appreciated look at an area of the industry that few of us get to see in detail.

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Light Guns Aren’t Just For CRTs Anymore

October 23, 2023 by 17 Comments

For how much of a cultural phenomenon light gun games like Duck Hunt were, they didn’t survive the transition from CRT televisions to LCDs particularly well because of all of the technological quirks the light guns exploited in older technology that simply disappeared with modern TVs. But it’s not impossible to get a similar gameplay from modern technology as evidenced by the success of the Wii and its revolutionary Wiimote, and there are plenty of modern games that use similar devices. There are a few paths to getting older light guns working again, though.

The first system to note, called SAMCO, uses a system of LEDs and a camera to synchronize the game’s flashes to the new technology and translate the input back into the game. Gun4ir uses a similar technique, and boasts extremely high accuracy and low latency largely due to being programmed in assembly. Both systems can use either an infrared tracking sensor or a Wiimote sensor as the LEDs and while the SAMCO system can run on a Raspberry Pi Pico, Gun4ir exclusively uses ATmega32U4 boards with the optimized assembly programming.

Both SAMCO and Gun4ir offer PCBs for anyone looking to try them out without designing their own circuit boards, and once the electronics are assembled they can either be put in an original NES-era light gun, put in a custom printed enclosure, or even stuffed into a Nerf gun. For others looking for a more turnkey solution, there are also offerings from companies like Sinden which make complete system. You can always build your own system to restore the functionality of original light guns from scratch if that’s more your style.

Thanks to [LookAtDaShinyShiny] for tipping us off to the latest happenings in the light gun community!

Photo courtesy of Wikimedia Commons

The IMac GPU Becomes Upgradeable, With PCIe

October 23, 2023 by 11 Comments

Over its long lifetime, the Apple iMac all-in-one computer has morphed from the early CRT models through those odd table-lamp machines into today’s beautiful sleek affairs. They look pretty, but is there anything that can be done to upgrade them? Maybe not today’s ones, but the models from the mid-2000s can be given some surprising new life. [LowEndMac] have featured a 2006 24″ model that’s received a much more powerful GPU, something we’d have thought to be impossible.

The iMacs from that era resemble a monitor with a slightly chunkier back, in which resides the guts of the computer. By then the company was producing machines with an x86 processor, and their internals share a lot of similarities with a laptop of the period. The card is a Mac Radeon model newer than the machine would ever be used with, and it sits in a chain of mini PCIe to PCIe adapters. Even then it can’t drive the original screen, so a replacement panel and power supply are taken from another monitor and grafted into the iMac case. This along with a RAM and SSD upgrade makes this about the most upgraded a 2006 iMac could be.

Of course, another approach is to simply replace the whole lot with an Intel NUC.

DIY Shredder Creates Insulation

October 23, 2023 by 28 Comments

Plenty of us have experience with paper shredders, but there are all kinds of machines designed to completely destroy other materials as well, from metal and plastic, to entire cars. [Action BOX] built their own heavy-duty shredder capable of dismantling things like cell phones and other robust handheld objects, but after seeing what it would physically shred they decided to give it an actual job creating insulation for the attic space in their garage.

The shredder itself uses opposing metal plates arranged on sets of two cylinders, with each cylinder powered by it’s own large motor. In total, the entire system uses around 1.5 kW, so to make their green insulation project as green as possible they decided to power it with an equivalent amount of solar panels. For the insulation they’re using a year’s worth of boxes from various deliveries, and after a time-consuming process preparing the boxes for the shredder, shredding the strips of cardboard, and packaging it in garbage bags their efforts netted them enough to partially fill the space between four ceiling joists. Continue reading “DIY Shredder Creates Insulation” →

Using LEDs To Determine A Video Camera’s True Framerate

October 23, 2023 by 17 Comments

Interpolation and digital cropping are two techniques which are commonly used by marketing folk to embellish the true specifications of a device. Using digital cropping a fictitious zoom level can be listed among the bullet points, and with frame interpolation the number of frames per second (FPS) recorded by the sensor is artificially padded. This latter point is something which [Yuri D’Elia] came across with a recently purchased smartphone that lists a 960 FPS recording rate at 720p. A closer look reveals that this is not quite the case.

The smartphone in question is the Motorola Edge 30 Fusion, which is claimed to support 240 and 960 FPS framerates at 720p, yet the 50 MP OmniVision OV50A sensor in the rear camera is reported as only supporting up to 480 FPS at 720p. To conclusively prove that the Motorola phone wasn’t somehow unlocking an unreported feature in this sensor, [Yuri] set up an experiment using three LEDs, each of which was configured to blink at either 120, 240 or 480 Hz in a side-by-side configuration.

As [Yuri] explains in the blog post, each of these blinking frequencies would result in a specific pattern in the captured video, allowing one to determine whether the actual captured framerate was equal to, less than or higher than the LED’s frequency. Perhaps most disappointingly about the results is that this smartphone didn’t even manage to hit the 480 FPS supported by the OV50A sensor, and instead pegged out at a pedestrian 240 FPS. Chalk another one up for the marketing department.

KaboomBox Is A Firecracker Of A Music Player

October 23, 2023 by 5 Comments

Ka-chunk. Let’s face it, 8-tracks were not that great. But the players, that’s another story. The Panasonic RQ-830S, aka the dynamite or TNT player is just one of many lovely designs that used to grace the shelves of electronics stores. Hackaday alum [Cameron Coward] came across a non-working model and used it to create the KaboomBox.

Just like before, all [Cameron] has to do is stick a tape in, and music starts playing. But now, instead of using rust on tape, the music is accessed via RFID and lives on an SD card inside the 8-track player.

Power it on, and a tiny LCD screen showing through the track number window first displays the KaboomBox logo, then shows a timer whenever it’s waiting for a tape. And just like before, pushing down on the plunger skips to the next track.

The new guts include a Raspberry Pi Pico and an RFID reader, plus a DF Player Mini to handle the digital-to-analog conversion and amplify the signal, and an SD card to store the music. Now, [Cameron] is only limited by the size of the SD card. Check out the demo video after the break.

We’ve seen all kinds of boomboxen around here, from the lit to the Bluetooth to the payphone variety.

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