Tiny Bubbles In The Memory

We are always fascinated by bubble memory. In the late 1970s, this was the “Next Big Thing” that, as you may have guessed, was, in fact, not the next big thing at all. But there were a number of products that used it as non-volatile memory at a time when the alternative was tape or disk. [Smbakeryt] has a cool word processor with an acoustic coupler modem made by Teleram. Inside is — you guessed it — bubble memory.

The keyboard was nonfunctional, but fixable. Although we wouldn’t have guessed the problem. Bubble memory was quite high tech. It used magnetic domains circulating on a thin film of magnetic material. Under the influence of a driving field, the bubbles would march past a read-write head that could create, destroy, or read the state of the bubble.

Why didn’t it succeed? Well, hard drives got cheap and fairly rugged. The technology couldn’t compete with the high-density hard drives that could be reached with improved heads and recording strategies. Bubble memory did find use in high-vibration items, but also wound up in things like this terminal, at least one oscilloscope, and a video game.

Bubble memory evolved from twistor memory, one of several pre-disk technologies. While they are hard to come by today, you can find the occasional project that either uses some surplus or steals a part off of a device like this one.

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Inside A Fake WiFi Repeater

Fake WiFi repeater with a cheap real one behind it. (Credit: Big Clive, YouTube)
Fake WiFi repeater with a cheap real one behind it. (Credit: Big Clive, YouTube)

Over the years we have seen a lot of fake electronics, ranging from fake power saving devices that you plug into an outlet, to fake car ECU optimizers that you stick into the OBD port. These are all similar in that they fake functionality while happily lighting up a LED or two to indicate that they’re doing ‘something’. Less expected here was that we’d be seeing fake WiFi repeaters, but recently [Big Clive] got his hands on one and undertook the arduous task of reverse-engineering it.

The simple cardboard box which it comes in claims that it’s a 2.4 GHz unit that operates at 300 Mbps, which would be quite expected for the price. [Clive] obtained a real working WiFi repeater previously that did boast similar specifications and did indeed work. The dead giveaway that it is a fake are the clearly fake antennae, along with the fact that once you plug it in, no new WiFi network pops up or anything else.

Inside the case – which looks very similar to the genuine repeater – there is just a small PCB attached to the USB connector. On the PCB are a 20 Ohm resistor and a blue LED, which means that the LED is being completely overdriven as well and is likely to die quite rapidly. Considering that a WiFi repeater is supposed to require a setup procedure, it’s possible that these fake repeaters target an audience which does not quite understand what these devices are supposed to do, but they can also catch more informed buyers unaware who thought they were buying some of the cheap real ones. Caveat emptor, indeed.

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Why Are Micro Center Flash Drives So Slow?

Every year, USB flash drives get cheaper and hold more data. Unfortunately, they don’t always get faster. The reality is, many USB 3.0 flash drives aren’t noticeably faster than their USB 2.0 cousins, as [Chase Fournier] found with the ultra-cheap specimens purchased over at his local Micro Center store.

Although these all have USB 3.0 interfaces, they transfer at less than 30 MB/s, but why exactly? After popping open a few of these drives the answer appears to be that they use the old-style Phison controller (PS2251-09-V) and NAND flash packages that you’d expect to find in a USB 2.0 drive.

Across the 32, 64, and 256 GB variants the same Phison controller is used, but the PCB has provisions for both twin TSOP packages or one BGA package. The latter package turned out to be identical to those found in the iPhone 8. Also interesting was that the two 256 GB drives [Chase] bought had different Phison chips, as in one being BGA and the other QFP. Meanwhile some flash drives use eMMC chips, which are significantly faster, as demonstrated in the video.

It would seem that you really do get what you pay for, with $3 “USB 3.0” flash drives providing the advertised storage, but you really need to budget in the extra time that you’ll be waiting for transfers.

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Teardown Of Casio Credit Card-Sized Radio

These days we don’t get too fussed about miniaturized electronics, not when you can put an entire processor and analog circuitry on a chip the size of a grain of sand. Things were quite different back in the 1980s, with the idea of a credit card-sized radio almost preposterous. This didn’t stop the engineers over at Casio from having a go at this and many other nutty ideas, with [Matt] from Techmoan having a go at taking one of these miniaturized marvels apart.

The Casio FM Stereo radio in happier days. (Credit: Techmoan, YouTube)

On the chopping block is the FM stereo device that was featured in a previous episode. Out of the four credit card-sized radios in that video, the one with the rechargeable battery (obviously) had ceased to work, so it was the obvious choice for a teardown. This mostly meant peeling off the glued-on top and bottom, after which the circuitry became visible.

In addition to the battery with a heavily corroded contact, the thin PCB contains a grand total of three ICs in addition to the analog circuitry. These were identified by [Spritetm] as an AM/FM tuner system IC (TA7792), an FM PLL MPX (TA7766AF) and a headphone amplifier (TA7767F), all of them manufactured by Toshiba.

Although [Matt] reckons this was a destructive teardown, we’re looking forward to the repair video where a fresh cell is soldered in and the case glued back together. Continue reading “Teardown Of Casio Credit Card-Sized Radio”

Wire Recording Speaks Again

If you think of old recording technology, you probably think of magnetic tape, either in some kind of cassette or, maybe, on reels. But there’s an even older technology that recorded voice on hair-thin stainless steel wire and [Mr. Carlson] happened upon a recorded reel of wire. Can he extract the audio from it? Of course! You can see and hear the results in the video below.

It didn’t hurt that he had several junk wire recorders handy, although he thought none were working. It was still a good place to start since the heads and the feed are unusual to wire recorders. Since the recorder needed a little work, we also got a nice teardown of that old device. The machine was missing belts, but some rubber bands filled in for a short-term fix.

The tape head has to move to keep the wire spooled properly, and even with no audio, it is fun to watch the mechanism spin both reels and move up and down. But after probing the internal pieces, it turns out there actually was some audio, it just wasn’t making it to the speakers.

The audio was noisy and not the best reproduction, but not bad for a broken recorder that is probably at least 80 years old. We hope he takes the time to fully fix the old beast later, but for now, he did manage to hear what was “on the wire,” even though that has a totally different meaning than it usually does.

It is difficult to recover wire recordings, just as it will be difficult to read modern media one day. If you want to dive deep into the technology, we can help with that, too.

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Inside A “Budget” Current Probe

Current measurements are not as handy as voltage measurements. You typically need to either measure the voltage across something and do some math or break the circuit so a known resistor in your instrument develops a voltage your meter measures and converts for you. However, it is possible to get non-contact current probes. They are generally pricey, but [Kerry Wong] shows us one under $200 and, thus, budget compared to similar probes. Check out the review in the video below.

The OWON unit has three ranges: 4 A, 40 A, and 400 A. It claims a resolution of 10 mA and a bandwidth of 200 kHz. It requires a 9 V battery, which [Kerry] suspects won’t last very long given the rated power consumption number, although the measured draw was not as high as claimed. The specs aren’t great — this seems to be little more than a current probe meter with a connector for an oscilloscope, but if it meets your needs, that could be acceptable.

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Canon Arc Form Drive exploded. Credit: Markus Kohlpaintner

A Deep Dive Into Canon Autofocus Lenses

Credit: Markus Kohlpaintner

Although taken for granted these days, autofocus (AF) used to be a premium feature on film- and digital cameras, with [Markus Kohlpaintner] taking us through an exhaustive overview of Canon’s AF systems and how they work. On Canon cameras AF became a standard feature with the introduction of its EF lenses in 1987, which are found on its EOS SLR (single-lens reflex) series of professional and prosumer cameras.

Over the decades, Canon has used many different AF drive mechanisms within these lenses, all with their own pros and cons. The article goes through each of them, starting with the original Arc-Form Drive (AFD) and ending with the newest Voice Coil Motor (VCM), showing their internal construction.  Of note are the USM (ultrasonic motor) types of AF systems that use a piezoelectric motor, the functioning of which using a traveling wave across the stator is also detailed, including the integrated feedback control system.

Ultimately the end user is mostly concerned with how well the AF works, of course. Here the biggest difference is probably whether manual adjustment is possible, with not all AF systems supporting full-time manual adjustment. With the newer AF systems this manual adjustment is now performed digitally rather than with a direct coupling. Although few people probably give AF much thought, it’s fascinating to see how much engineering went into these complex systems before even touching upon the algorithms that decide what to focus on in a scene.