Monochrome LCD Video Hacks Galore!

May 12, 2022 by Dave Rowntree 23 Comments

[Wenting Zhang] is clearly a fan of old school STN LCD displays, and was wondering how various older portable devices managed to drive monochrome LCDs panels with multiple grey levels. If the display controller supports multiple bits per pixel, it can use various techniques, such as PWM, in order to produce a pseudo-grayscale image. But, what if you have a monochrome-only display controller? With a sufficiently high pixel clock, can you use software on the application side of things to flip those pixels in such a manner as to give a reasonable looking grayscale image?

Simple dithering – don’t look too close!

PDM greyscale approximation in a 1-bit display

[Wenting] goes through multiple techniques, showing the resulting image quality in a clear, systematic manner. The first idea is to use a traditional dithering technique. For each pixel, it is set to black if the grey value is below some threshold. The resulting error value, is then propagated to neighbouring pixels. This error diffusion process smears the error out over the whole display, so spatially speaking, on average the pixel values correspond roughly to the original gray values. But, the pixels themselves are still either on or off. This isn’t quite enough. The next idea is to PWM the individual pixels over multiple frames, to approximate different grey levels. But, that gives a worst case effective refresh rate of 8 Hz with a PWM period of 15 frames, at 120 fps, and that flickers. Badly. One way to mitigate that is to switch to PDM (pulse density modulation) which selects different length sequences to give the same duty cycle but at higher frequency, at least for some grey values. Slightly better, but there’s more that can be done. Continue reading “Monochrome LCD Video Hacks Galore!” →

New Tech And The Old Ways

April 30, 2022 by Elliot Williams 8 Comments

This week on Hackaday, we featured a project that tickled my nostalgia bone, and proved that there are cool opportunities when bringing new tech to old problems. Let me explain.

[Muth] shared a project with us that combines old-school analog photography printing with modern LCD screens. The basic idea is to use a 4K monochrome screen in place of a negative, making a contact print by placing the screen directly on top of photographic paper and exposing it under a uniform light source. Just like the old ways, but with an LCD instead of film.

But what’s the main difference between a screen and film? You can change the image on the LCD at will, of course. So when [Muth] was calibrating out exposures, it dawned on him that he could create a dynamic, animated version of his image and progressively expose different portions of the paper, extending the available dynamic range and providing him the ability to control the slightest nuances of the resulting image contrast.

As an old photo geek, this is the sort of trick that we would pull off manually in the darkroom all the time. “Dodging” would lighten up a section of the image by covering up the projected light with your hand or a special tool for a part of the exposure time. With [Muth]’s procedure, he can dodge the image programmatically on the per-pixel level. We would have killed for this ability back in the day.

The larger story here is that by trying something out of the box, applying a new tool to an old procedure, [Muth] stumbled on new capabilities. As hackers, we’re playing around with the newest tech we can get our hands on all the time. When you are, it might be that you also stumble on new possibilities simply afforded by new tech. Keep your eyes open!

Stresses Revealed With A Polariscope

April 1, 2022 by Bryan Cockfield 13 Comments

There are a lot of ways that stresses can show up, at least when discussing materials science. Cracks in concrete are a common enough example, but any catastrophic failure in a material is often attributable to some stress that couldn’t be withstood. If you’re interested in viewing those stresses before they result in damage to the underlying material, take a look at this DIY polariscope which can view internal stresses in glass and other clear objects.

The polariscope takes its name from the fact that it uses polarized light to view the internal structure of a transparent object such as glass. When the polarized light passes through glass in a certain way, the stresses show up as lighter areas thanks to the stressed glass bending the light back into view. This one is constructed with a polarizing filter placed in front of an LCD screen set to display a completely white image. When glass is placed between the screen and the filter no light is seen through the polariscope unless there are stresses in the glass. Even placing a force on an otherwise un-stressed glass tube can show this effect, and [Advanced Tinkering], this project’s creator, has several other creations which show this effect in striking detail.

The effect can also be observed as colored areas in other plastic materials as well. It’s an interesting tool which can help anyone who frequently works with glass, but it’s also interesting on its own to see clues left behind from the manufacturing process of various household items. We’ve seen some other investigative methods for determining how other household items are mass produced as well, like this project which breaks down the injection molding process.

Continue reading “Stresses Revealed With A Polariscope” →

The hairclip-embedded tool being used on a Tiger 99x game console, clipped onto a spot where the plastic ribbon meets the LCD panel itself, heating it up

World’s Smallest Hair Straightener For Fixing Old LCD Ribbons

March 19, 2022 by Arya Voronova 8 Comments

[Stephen] writes to us about an LCD repair tool he has created. We’ve all seen old devices with monochrome LCDs connected by thin film, where connections between the PCB and the LCD have deteriorated and the LCD would no longer show parts of the picture. This is a connection heating gadget, that [Stephen] affectionately dubs as World’s Smallest Hair Straightener, made specifically to bring cool old tech back to life.

A resin-printed mold houses a coil of Kanthal wire, easy to source and simple to make. He reuses a hair clip as a housing for the heating element, which also provides pressure needed to squish the film-printed conductive traces into the LCD as the adhesive melts. High-temperature epoxy brings the two together, and with a variable power supply, this tool successfully brought an old Tiger 99x handheld back to life.

This hack was made possible, in part, because of [JohnDevin Duncan] in Hackaday comment section sharing his experience on repairing LCD ribbons back in 2015, giving valuable insights on the problem that we initially thought would be solve-able with a soldering iron. The knowledge shared was distilled by [Stephen] into a tool that we all can now use when we encounter a device we really, really want to revive.

Last time we covered this topic, quite a few hackers popped up with their stories and suggestions. Old game console fix stories are a staple here on Hackaday, a few pop to mind – this high-effort trace repair of a water-damaged GameBoy cartridge, a badly designed NES cartridge socket reinvention, and this GameBoy LCD sunburn damage restoration guide.

Haptic Smart Knob Does Several Jobs

March 13, 2022 by Ryan Flowers 63 Comments

A knob is a knob, a switch is a switch, and that’s that, right? And what about those knobs that have detents, set in stone at the time of manufacturing? Oh, and those knobs that let you jog left to right and then snap back to center — that can’t be modified…right? Well, you likely know where this is going, and in the video below the break, [scottbez1] shows off a new open source haptic input knob that can be all of these things with just some configuration changes!

The list of possibilities is long: virtual snap points, virtual spring loading, virtual detents, virtual end points. It’s a virtual smörgåsbord of configuration options that make this haptic smart knob a one stop shop for all of your knob needs. This is all possible because the knob contains a high resolution magnetic encoder chip that has a single degree resolution. The sensor is coupled, through software, to a brushless DC motor. The round LCD gives visual feedback as well.

As [Myself] on the Hackaday Discord channel noted, having configurable spacing and strength for detents, springs, and stops, is nothing short of incredible. Being able to reconfigure the knob at-will means that it can become context sensitive. It’s wonderfully unique and it’s open source, so you can make your own with the information available at GitHub.

And according to its creator, the only thing the Haptic Smart Knob can’t do is do your taxes or blend your margarita. Well, it’s open source, so perhaps some of our more enterprising readers can submit just the right pull request.

This isn’t Hackaday’s first Motorized Volume Knob feature, but it might be one of the neatest we have seen so far. Thanks to [mattvenn] on the Hackaday Discord server for the great tip!

Continue reading “Haptic Smart Knob Does Several Jobs” →

Vintage Multimeter Gets An LCD Transplant

March 8, 2022 by Zoe Skyforest 10 Comments

Hackers are often of the sentimental type, falling in love with the look and feel of quality old hardware. Of course, sometimes that older hardware needs a little TLC to keep it running in the modern world. [Lex] had a beautiful vintage multimeter that sadly had a broken screen, and set about a nifty repair to restore it to working condition.

The HSN Avometer DA116 is a handsome thing, controlled with two dials and featuring a clean two-tone aesthetic. Even the font on the PCB’s silkscreen is gloriously pretty (can anyone ID that?). However, the original LCD was non-functional. A direct replacement part was sadly unavailable. Instead, to rectify this, [Lex] first hunted down another segmented LCD screen that had the same segment layout.

However, the new screen had a completely different pinout to the original part. Thus, after taking some notes and figuring out what all the pins did, [Lex] whipped up an adapter board to carry the new screen. With some protoboard, some pin headers, and a bunch of point-to-point wiring, the new screen worked just fine, and [Lex] had a functioning vintage meter once again!

The story actually came to us on Twitter, where we invited discussion about the best bodge wiring jobs out there. Feel free to contribute your own stories to the conversation! If you’re in the market for more LCD hacking, be sure to check out the excellent talk [Joey Castillo] gave at the 2021 Remoticon.

Remoticon 2021 // Joey Castillo Teaches Old LCDs New Tricks

February 24, 2022 by Zoe Skyforest 6 Comments

Segmented liquid crystal displays are considered quite an old and archaic display technology these days. They’re perhaps most familiar to us from their use in calculators and watches, where they still find regular application. [Joey Castillo] decided that he could get more out of these displays with a little tinkering, and rocked up to Remoticon 2021 to share his findings.

[Joey’s] talk is a great way to learn the skills needed to reverse engineer a typical segment LCD.

[Joey] got his start hacking on these displays via his Sensor Watch project – a board swap for the venerable Casio F-91W wristwatch, with the project now available on CrowdSupply. It kits out the 33-year-old watch design with a modern, low-power ARM Cortex M0+ microcontroller running at 32 MHz that completely revolutionizes what the watch can do. Most importantly, however, it repurposes the watches original segmented monochrome LCD.

Segment LCDs are usually small monochrome devices made out of glass, that have the benefit of using very little power in their operation. They come with a fixed layout, which cannot be changed – so they’re often designed specifically for a given purpose. A calculator will have segments laid out to display numbers, often in the usual 7-segment fashion, while a watch may add dedicated segments for displaying things like “AM,” “PM,” or “ALARM.” Continue reading “Remoticon 2021 // Joey Castillo Teaches Old LCDs New Tricks” →