Teardown

548 Articles

Inside A Vintage Oven Controlled Crystal Oscillator

February 1, 2025 by 8 Comments

Crystal oscillators are incredibly useful components, but they come with one little snag: their oscillation is temperature-dependent. For many applications the relatively small deviation is not a problem, but especially for precision instruments this is a deal breaker. Enter the oven controlled crystal oscillator, or OCXO. These do basically what it says on the tin, but what’s inside them? [Kerry Wong] took apart a vintage Toyocom TCO-627VC 10 MHz OCXO, revealing a lot more complexity than one might assume.

Inside the insulated enclosure there is of course the crystal oscillator itself, which has a heating coil wrapped around it. Of note is that other OCXOs that [Kerry] took apart had more insulation, as well as other ways of providing the thermal energy. In this particular unit a thermistor is attached to the crystal’s metal case to measure its temperature and provide feedback to the heating circuit. The ICs on the PCB are hard to identify due to the conformal coating, but at least one appears to be a 74LS00, alongside a 78L05 voltage regulator which reduces the 12V input voltage.

As an older OCXO it probably is a lot chunkier than newer units, but the basic principle remains the same, with a heating loop that ensures that the crystal inside the unit remains at the same temperature.

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A 1962 Test Gear Teardown

January 30, 2025 by 11 Comments

Although it sounds like some Star Trek McGuffin, a Q-Meter is a piece of test gear that measures the Q factor of a tuned circuit. [Thomas] got a Boonton meter from 1962 that wasn’t in very good shape, but it was a fun teardown, as you can see in the video below. The meter had signs of a prior modification or repair, but still a nice peek into some vintage gear.

The meter could measure up to 260 MHz (or megacycles in 1962 parlance) and had some unusual features, including an oddly wired AC transformer and a “voltage stabilizer” to ensure a constant AC voltage at the input. We have to admit, we miss the days when our test equipment had gears inside. Then again, we don’t miss the tubes and the high-voltage stuff. Because of the high frequency, the unit even has an oddball acorn tube that you rarely see.

You may notice the meter has a mirror in a strip on the face. This is a common feature of high-precision analog meter movements. The idea is that you move your head until the needle hides its own reflection in the mirror to avoid parallax errors in your reading.

This isn’t the first Q meter we’ve seen; in fact, one was pretty similar but a bit older. While you can get a lot of new gear cheap these days, there’s still something to be said for vintage test equipment.

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A dismantled drill on a cluttered workbench

Going Brushless: Salvaging A Dead Drill

January 29, 2025 by 26 Comments

Let’s face it—seeing a good tool go to waste is heartbreaking. So when his cordless drill’s motor gave up after some unfortunate exposure to the elements, [Chaz] wasn’t about to bin it. Instead, he embarked on a brave journey to breathe new life into the machine by swapping its dying brushed motor for a sleek brushless upgrade.

Things got real as [Chaz] dismantled the drill, comparing its guts to a salvaged portable bandsaw motor. What looked like an easy swap soon became a true hacker’s challenge: incompatible gear systems, dodgy windings, and warped laminations. Not discouraged by that, he dreamed up a hybrid solution: 3D-printing a custom adapter to make the brushless motor fit snugly into the existing housing.

The trickiest part was designing a speed control mechanism for the brushless motor—an impressively solved puzzle. After some serious elbow grease and ingenuity, the franken-drill emerged better than ever. We’ve seen some brushless hacks before, and this is worth adding to the list. A great tool hack and successful way to save an old beloved drill. Go ahead and check out the video below!

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A Look Inside A Modern Mixed Signal Oscilloscope

January 18, 2025 by 5 Comments

High-speed bench equipment has become so much more affordable in the last decade that naturally one wonders what has made that possible. A great source of answers is a teardown by users like [kerry wong] who are kind enough to take apart their MSO2304X 300MHz osilloscope for our viewing pleasure.

The posted teardown video shows the guts of the scope without enclosure, heatsinks and shields that reveal a handful of boards that execute the functions nicely. The motherboard uses the Xilinx KINTEX-7 FPGA that is expected to run core processes such as signal processing as well as managing the sample storage on the paired DDR3 memory.

The analog front-end here is a bit of a surprise as it sports TI’s ADC08D1000 ADCs that are capable of 1.3 GSPS but the scope is advertised to be capable of more. The inferred design is that all four ADCs are being operated in an interleaved symphony to achieve 5 GSPS. Testing confirms that each input uses two ADCs at a time and when two or more channels are employed, the reconstruction quality drops.

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Investigating USB-to-Ethernet Dongles With “Malware” Claims

January 18, 2025 by 56 Comments

Recently a video surfaced from someone claiming that certain USB-to-Ethernet dongles contained ‘malware’ among other big claims. Basically these dongles were said to be designed by China (and Russia) to spy on users and so on, but how much of this is actually grounded in reality? When [lcamtuf] dove into the topic, what he found was not so much a smoking gun, but rather a curious relic from the era when drivers-on-CD were being phased out.

The item that the video went bananas about was namely an additional SPI Flash chip on the PCB alongside the USB 2.0 – Ethernet IC, with many conspiracy theories being floated as to what it would be used for. After some digging, [lcamtuf] found that the IC used in these dongles (SR9900) is by a company called CoreChips Shenzhen, with a strong suggestions that it is a clone of the (2013-era) Realtek RTL8152B.

Both chips have an external SPI Flash option, which is used with the USB side to present a ‘virtual CD drive’ to the user when the dongle is plugged in. This was borne out with the SR9900 Windows system mass production tool that [lcamtuf] obtained a copy of. Included with the flashing tool is a 168 kB ISO image (containing the SR9900 driver package) which happily fits on the 512 kB Flash chip.

Although it’s always possible for chips and firmware to contain backdoors and malware, in this particular case it would appear to be that it’s merely a cruel reminder that 2013 is now already vanishing into the realm of ‘retro computing’ as us old fogies cling to our driver installation floppies and CDs.

Stacy’s Computer Has Got It Going On

January 5, 2025 by 14 Comments

According to [ClassicHasClass], the best way to open an Atari Stacy is to not open an Atari Stacy. Apparently, these old computers were not pleasant to work on. The cables were not keyed and were prone to short against things. Screws easily strip out plastic holes. Of course, there wouldn’t be a story if there wasn’t a teardown and an upgrade that you can check out in the post.

The Stacy was one of Atari’s earliest portable systems and the first ST portable (that is, STacy). There’s a backlit LCD, a keyboard and trackball, and the usual ports. You could make do with a single floppy or spring for a second floppy or an internal SCSI hard drive. The 8 MHz 68000-based machine would set you back north of $2,300 back in 1989.

The original plan was to run the thing on C-cell batteries, but that would give you about 15 minutes of operation. They finally decided it was a luggable — you’d have to plug it into the wall. The battery compartment was there, but empty and glued shut.

Apparently, there were about 35,000 of these made, but they seem somewhat rare. But we do like a rare retrocomputer. Or even some that aren’t so rare.

close up hands holding lighting pcb

Circuit Secrets: Exploring A $5 Emergency Light

December 28, 2024 by 2 Comments

Who would’ve thought a cheap AliExpress emergency light could be packed with such crafty design choices? Found for about $5, this unit uses simple components yet achieves surprisingly sophisticated behaviors. Its self-latching feature and decisive illumination shut-off are just the beginning. A detailed analysis by [BigCliveDotCom] reveals a smart circuit that defies its humble price.

The circuit operates via a capacitive dropper, a cost-effective way to power low-current devices. What stands out, though, is its self-latching behavior. During a power failure, transistors manage to keep the LEDs illuminated until the battery voltage drops below a precise threshold, avoiding the dreaded fade-to-black. Equally clever is the automatic shut-off when the voltage dips too low, sparing the battery from a full drain.

Modifications are possible, too. For regions with 220V+ mains, swapping the dropper capacitor with a 470nF one can reduce heat dissipation. Replacing the discharge resistor (220k) with a higher value improves longevity by running cooler. What remarkable reverse engineering marvels have you come across? Share it in the comments!  After all, it is fun to hack into consumer stuff. Even if it is just a software hack.

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