Carl's Notes

So, I've been stressing over nothing, it seems. I'd been under the impression that I'd need to build a whole control circuit, with multiple switches (power, heating/cooling, and intensity), on a circuit board, putting a PC power supply on my desk, it turns out none of that is necessary for testing purposes!

This realization has led to me dropping a PC power supply on my chair, plugging a PC power supply adapter board into it, unplugging the Peltier device from the original control board, and somehow connecting it to the adapter board.

And it worked just fine!

I don't know if it got colder, but it definitely got cold faster! A very worthwhile effort!

Unfortunately, I didn't realize that the PC power supply had a fan in it, nor that it would be loud enough to be distracting.

Fortunately, I now know that I don't need a huge array of controls (after all, I only use it to cool drinks, not warm them. Nor do I need to change the voltage the Peltier device runs at), as well as knowing that I can use almost any 12V supply for this project. Time to look at my other options!

Varnishing is hard. Especially since almost every woodworker I've been following on YouTube entirely skips over the whole process, going straight from "this is what it looks like before" to "this is what it looks like afterwards" in one jump cut.

What I really need is a text tutorial (NO, video tutorials do NOT work for me! I should write a post on why eventually...) that explains every step in the process. Also what to do when things look particular ways.

The very first thing I'd varnished was a small (four-inch in diameter) attempt at a wooden coaster, so a full paint brush basically drank more varnish than I was able to spread onto the surface. So I'd used a sponge brush instead, and it worked better in that situation.

In this situation, it didn't lay down enough varnish, and two thin coats didn't look like much.

Given the larger surface to cover, I brought the paintbrush back out, and it actually laid down enough varnish to almost look professional!

If it had been a smooth enough layer, I would have left it at that, but it needs sanding smooth again. Which means I need to know what grit of sandpaper to use to avoid making it worse...

A few years ago, I'd found a dual-function drinks coaster. At the moment, the house I'm living in doesn't have anywhere near enough insulation, so I'd been looking for a drinks coaster that was capable of cooling my drinks. Having a glass of juice with lime in it was fairly effective at keeping me cool, but only when the drink wasn't allowed to get that hot.

Anyway, while most electric drinks coasters just heat your drinks, the one I'd found also included a cooling function. Though, I suspect it's less effective given that it's USB powered instead of wall-powered.

Now, in larger heat-moving systems, a highly compressible gas is used to literally pump heat (hence, "heat pump") around, but in much smaller systems like this, you can buy solid-state devices that move heat around to a less efficient extent. Called Peltier devices, if you hook it up to power the right way around, it uses the flow of electricity to move heat from one side to the other. A higher voltage moves more heat around, in this case, and while it comes with a USB cable by default (thus running at 5V), you are supposed to be able to buy a 9V power adapter separately, which increases the amount of heat it pulls out of your drink.

On the opposite side of the coin, if you apply the power in the opposite direction, it instead generates heat, and the power switch on the front of the coaster toggles which direction the power is applied.

Unfortunately, the cooling function has two separate flaws. The first being a small fan. This fan blows air across the bottom side of the Peltier device, with the intent to blow the heat pulled from your drink away, but it's noisy enough to be a distraction most of the time.

The second being that cold doesn't rise. Which means that, if your drink starts out being warmer, you end up with a temperature gradient in your cup, with the bottom layers being colder than the top layers.

With the modicum of success I'd found using this device, and finding that its price had dropped afterwards, I'd bought a couple more. The idea being to experiment with it. For example, fixing the fan noise problem would be simple enough hardware wise, by replacing the original fan with a larger module, which is quite easy to obtain and I've already done so. Structurally, however, I'm still trying to figure out how to support the whole thing, as there's nowhere near enough empty space for a fan of this size in it, so I basically need to build a new frame to support it. Given my limited set of tools and experience, a lot of thought is required here.

But, that doesn't solve the second problem. How do you make an entire glass of water (for example) colder at the same time? Do you mount the Peltier device so it makes contact with the side of the glass instead of its base? Being spring-loaded such that it pivots back and forth as necessary to make contact with the side of the glass, no matter what angle it's on? Maybe with a flexible air duct from the base to the bottom of the heat sink already attached to the Peltier device, so the fan in the base forces a lot of air through it?

Unfortunately, that concept doesn't quite work here, as all of my glasses are round in two dimensions, such that a flat object pressed against them would make contact at a single point, not even a line. Thus, heat transfer would be highly inefficient.

You can see my dilemma, and why I haven't tried doing anything else with this concept just yet. Granted, with how many of these I have right now, I could probably make one that just has a larger fan and contacts the bottom of the glass, then keep fiddling with another to see if I could make it any more efficient.

I should have waited until later to post my last update, as (given that it was a lovely day again today) I took my scroll saw back out and made another attempt to accomplish this cut.

This time, I knew better what kind of effort was needed to get the previous cut cleaned up, so was able to make it actually really, really close to the lines I'd drawn (this time in pencil, instead of a metal scribed line that was harder to see last time), which means I'll have less sanding to do to make sure it's as smooth as I want it.

Granted, if I'd had access to either a band or a table saw, I would have been done these cuts in less than ten minutes, with far more accurate cuts than I'd have got by hand. But right now, I don't have one, so I'm using what I've got for the moment.

Given that this is still the first scroll saw I've ever used, I still don't know everything I should know about how to use it, but I have noticed that this one seems to like moving to the right as I push the wood backwards. I hadn't taken this into account for my second ever cut attempt, and tried to arrange the second cut so the section I'd wanted to keep was on the wrong side.

A bit of short-term-memory refreshing later, I measured the remaining wood again, and found that I had enough room on the opposite side (given that I'd kind of ruined the first section I'd intended to use), so drew another line to cut along and actually was far more successful cutting along that one than the prior line.

So I now have both pieces (which will act as the vertical supports for the monitor stand I've needed since rearranging my desk to fit a new monitor I picked up off the curb, months ago) clamped together, in preparation for sanding them smooth and even. Once I get that done, I'll be able to drill the screw holes, screw them together, then add some varnish and set it in place.

Actually, I still need to decide whether to make some bevel cuts on the front and back of each "leg" plate, to leave room for wires and such. I should probably do those right after I sand their other sides, now that I think about it...

Anyway, the scroll saw blade may need replacing sooner rather than later, but as I don't have any right now, I'll have to figure out an alternative option for the moment. Given the way the current blade attaches, I'm very tempted to take a coarse hacksaw blade, cut it shorter, then punch thin holes in each end for a short length of thin metal rod. In the approximate configuration of the current blade, that is. Maybe it'll work?

Way back in 2016, I'd backed the Kickstarter campaign for Jide Tech's Remix Mini, a hand-sized (including fingers, so not palm-sized) Android PC, claiming to be the first Android desktop PC. Being very small and lightweight, but supporting most Android apps at the time, the idea was to get a pretty full desktop experience from the device.

I enjoyed fiddling around with it once I got it, but at the time I hadn't figured out how I was going to use it on a regular basis, as well as them launching a second campaign for a newer device that was supposed to be way more powerful. So I'd shelved it for a while, as I thought it was going to be replaced with a newer model that should have been better.

Unfortunately for me (but I guess fortunate for them), they drew the attention of a thin-client enterprise company, and they were basically swallowed whole. The campaign was shut down, and everybody got their money back, but nobody else got the product in the end.

A few years ago, I'd tried to boot my Remix Mini again to see if it still worked, but it didn't do anything at the time, so I put it even deeper on the shelf and forgot about it again.

Well, I came across the power cables again, and precariously perched it on my desk to give it another try. Unfortunately, I don't have any monitors with a spare HDMI port, so I plugged it into my HDMI capture device, and viewed the stream with VLC. And it booted all the way up, even to the desktop again, with no problems. Even connected to the WiFi again (we might need to change the WiFi information at some point) and realized that I need to update my login credentials!

Anyway, I've shut it back down for the moment so I can figure out my next step. I'd like to be able to have it running on my desk alongside everything else, as I do a lot more things now that would actually work on a system like this. Only, it's a really old OS now, I'm not sure how many of my apps would actually support it anymore.

Oh well. Back on the shelf again. But more towards the front this time, I think...

I mentioned that one of the things I want to do is install an FM radio module into a set of PC speakers, but didn't actually say what kind of radio module I had. While there are a lot of small circuit boards with the necessary chips (and sometimes the crystal for frequency stability), but no antenna, audio amplifier, display, or control scheme. For boards like that, it's just a small part (literally!) of a larger system.

Instead, the modules I have (and I have a few, they're cheap from China, where they're made) include an LCD screen to show what frequency they're on, signal strength, mute setting, and more. Most of them have buttons for volume, channel, and mute, but one even has no buttons and a bunch of through-holes for external control signals. Mostly buttons, admittedly, but the option is there for controlling it with another device.
(at the time of writing, <url="https://www.aliexpress.com/item/33038696986.html">this set of FM radio modules is a good example of the variety available. Searching AliExpress for "FM radio lcd" also should show most of these options, should the one I've linked to disappear)

Anyway, one of the annoyances of all of these modules is that they all use a blue LED to backlight their LCD displays, and it's only on for a short while after being interacted with. And since I'm sick and tired of blue LEDs nowadays, and would prefer the backlight stays on while the device is powered, and it turns out, the very first FM radio module I'd bought had an LED I could swap out. Nowadays, the LED is glued in place, with very short legs that go directly into the PCB. Fortunately, I was able to swap out the blue LED for a (supposedly) yellow one, then connect it to power and ground through a current-limiting resistor.

That looks like this now:



And I'm quite happy with the results, especially because it's not looking yellow, but orange, a much softer, more welcoming colour that I'd actually wanted in the first place. So it was a pleasant surprise to get that colour of backlight out of all the options I currently have access to.

Now, one of the things I'd noticed on all of the FM radio modules I've bought thus far is a set of three smaller through-hole pads labeled RX, GND, TX. It turns out, the control chips include a serial communications protocol that I'd hoped would allow me to pull the RDS (Radio Data System) information out of the module. After all, looking up the datasheet for the actual FM radio chip used on these boards (the Quintic QN8035, in my case) does support decoding this information.

It took me on a very weird dive, but I eventually found someone's own report on their dive into this, with a load of half-Chinese, half-English screenshots of command sets, and the specifications for the UART settings. The commands I've found thus far mostly includes every variation to the buttons already on the devices, including setting the tuned frequency directly, setting volume levels directly or just up or down, the backlight setting (turns out, it can be changed, just not through buttons), nearly full control over scanning for stations, and squelch settings.

But not the RDS information. Rather disappointing. But at least it means I won't need to devote any more time to thinking about trying to add this function to my current plans.

One advantage of the particular board I'm using, is that it includes two three-Watt speaker amplifier chips, so I don't need to add any more hardware to driver speakers.

On the other hand, if I wanted to make sure I had access to this information, I had bought a demo board showcasing the Silicon Labs Si4702. Either that or the Si4703. And unfortunately, that last digit is not listed on the chip itself, so I don't know which chip it actually is. And the -02 version doesn't have RDS support. But, on the other hand, it also doesn't have a display or buttons, so directly interfaces with a microcontroller. It just has the massive disadvantage of not having a separate antenna input, as it uses a headphone cable instead, so no driving speakers either.

Anyway, as you might be able to tell from the picture I've posted above, the LCD panel has lifted off the backlight diffusing panel (due to me fiddling around with it for years without mounting it into anything), so to install it into the speaker housing, I need to clamp it down to be flat again. Actually, I was going to write about that task here, but I think I'll write a separate journal entry about that...

So, some progress, I guess?

While the headphones I use the most are fully wireless BlueTooth ones, I started off with Sony's MDR-G45 (not the in-ear G45LP that came later, I gather) and used them a lot. I listened to a ton of music on my MP3 players through those!

Enough that I have at least two pairs right now, and both should have broken wires near the plug end by now. One is stored in a box for further experimentation (I'd wanted to convert them to pure BlueTooth at one point, but never quite figured out how at the time), and the other is hanging over my desk as a backup option for my gaming headset.

This latter pair definitely had a problem with its cable, as I'd tried to listen to something on my laptop, but its cable definitely caused problems.

It took me a while to figure out how to solder to the new plug (as there's no tabs like on older style plugs), but it's working again.

Slightly annoyingly, I have a whole bag full of four-contact 3.5mm headphone plugs, but appear to be entirely out of the three-contact ones. Much as I'd have loved to use a standard three-contact plug (due to it only being a pair of headphones with no microphone), as all I have are four-contact, I'd wanted to include both a microphone jack and a play/pause button. Because the option is there, of course.

I'd even found the information necessary to add up to three additional buttons for other functions, but didn't have the confidence to give that a try at the time.

But it works now, and I have ideas for how to add functionality for next time, so we'll see how long this repair lasts.

The general concept for this project is having a collection of wireless temperature (and more, hopefully) sensors I can place in various locations (outside front and back, garage, etc) that we can monitor from multiple locations, via a web server somewhere in the house.

Currently, I have two cheap wireless temperature sensor systems from the same company, and it turns out both use the same remote sensors, with no way to prevent their base stations from listening to the other sensor. And technically, the same brand does sell a "double" base station with two sensors, but the price jumps a lot from any of their one-sensor models, and I couldn't afford it. Conversely, I already have a bunch of pieces that could, theoretically, be turned into a small network of wirelessly-connected temperature sensors.

I even have a pretty solid idea of how to handle the hardware of the remote sensors. The inexpensive microcontrollers by Espressif are both inexpensive, and all include WiFi capabilities. Then there's a massive list of easily connected tempearture, humidity, and pressure sensors for very little money.

On the positive side, the actual sensor modules are both cheap, and quite easy to connect in hardware, and talk with in software. I've chosen which module I want to use, but if I need to change to another one, it won't be that difficult to swap out software libraries to make sure it still works.

The more interesting part is the microcontroller. While I have a variety of them (I've been buying samples in a wide variety for quite while now, mostly out of curiosity), I'm leaning towards the ESP32 series. They also have BlueTooth capabilities, not that I think I'll be using that, but also are all dual-core, with at least one real-time clock, and that's about perfect for what I want to accomplish with it.

The other half of the system is actually a lot trickier than I'd anticipated. A single-board computer (shortened to SBC, apparently) that can run "normal" software (as opposed to embedded software) is my aim, for many reasons. These include compact size, quiet operation, built-in WiFi and wired network capabilities, and hard storage of some sort. The Raspberry Pi is a very attractive option to me for all of these reasons, but I didn't realize I'd wanted to experiment with something like this until very recently, and not only do I not have the funds for it, but the supply has actually been drying up due to many reasons. There may be "compatible" alternatives, but I'm not comfortable with them right now due to not knowing how well-documented they are.

Unfortunately, because it's essentially a system in two parts, I can't really build one half at a time, as the other half would need to be in place for testing. And I work so much better sort of building the whole thing up at the same time.

One thing that's holding me back right now is due to not understanding Linux's Network Manager system. Technically, if I was writing the central server code on my laptop (for eample), I could write the remote sensor module code to talk to the laptop's server code. But I'm not comfortable putting the password to our home WiFi network directly into my source code, even for testing.

Instead, I want to have a separate WiFi card that hosts its own WiFi network, without linking it to any other networks connected to the computer. Hopefully that improves additional security measures. I have a secondary USB WiFi adapter, and it works, but I don't remember how to make it start working again. Unfortunately, Linux WiFi drivers are in a terrible state of affairs, and nobody seems to have a central repository for USB WiFi device drivers.
(from recent experience, I'm not even convinced that Windows can easily do what I'm trying to do, either)

Apparently, I don't have many friends on here that have come over from LJ, so it's been less than encouraging to post here. I'm going to try posting again, and will see what happens.

Here, I'm going to comment on some of the many and varied projects I'm working on, in no particular order.

#1: "Xtris", a Tetris clone for the "Xtron Pro"

I'm quite interested in hand-held devices I can program myself, and one Kickstarter I'd backed years ago was for the "PocketStar" keychain-sized "retro" gaming device. Programming them is as easy as setting your Arduino development environment (IDE) for the device and hitting "Compile". I'd enjoyed this one enough, and broke mine through my own fault, so had ordered a pair of replacements, though they don't have anything larger from that company.

So I backed something that was larger, and advertised a relatively simple programming interface. It turned out to be called the "Xtron Pro", and isn't actually intended for the "average" retro gamer or retro game programmer. No, it's intended for kids learning to program. Which has some really frustrating limitations. For example, it uses a 16-colour palette. For the entire screen. As in, you can't show more than that many colours on the screen at a time. And the default colour palette isn't all that great, though you can change that at run-time. But not in the built-in image editor. So you have to know what you're doing when building your images.

Yes, I am still trying to do this, but it's slow going. Another problem is that you can't write C or C++ programs for it, at least not with the systems it comes with. Instead, you can use JavaScript or Python, both of which I'm familiar with as languages, but the API you're supposed to use is painfully poorly documented.

But it's coming along, and I've got the majority of the immediately important visuals already completed. Up next is the actual interactive parts, including all the animations I'll want to use. Though, with how much I'm having to learn about this platform as I go, it is in deed slow going.

#2: Remote Temperature Sensors

I know such things already exist commercially, but the problem I've run into actually started with the limitations of two such cheap commercial units. I bought a sensor/base station set by Le Crosse, which turned out be rather useful and quite accurate at our last house, because the shed had a tarp on one side which protected the sensor from direct sunlight. When we moved into this house, we didn't have anywhere near as useful a place to stick the sensor, and during a summer we had questions about how hot the garage was getting (as we store a second fridge and two upright freezers in there), so my temperature sensor got moved down there and never moved again.

After which I bought a second, different model of sensor/base station pair from the same brand. And they started to interfere with each other. Turns out, it's a serious limitation of the protocol (as someone has reverse-engineered it and published the information online), and there's nothing I can do about it at all. So I bought second one, from a different brand, which has worked well enough so far.

But, you know, there's other features I'd like to have. Given how difficult it is to have entirely reliable temperature sensors that are not influenced by direct sunlight, or sunlight heating up the grass below the sensors, I kind of want to have at least one sensor to the east of the house, another to the west, and maybe incorporate another one for the one in the garage. And, of course, three doesn't need to be a solid limitation. Plus, I'd like to be able to tell how humid it is outside, as I don't have any way to tell that right now.

So I have an idea of how to do it, but there's some limitations, and I'll want to do at least a few posts on how that's coming.

#3: USB-connected Media Remote keyboard

Unlike every other Android device I've ever had, the two Asus ZenPad 10 tablets I have don't like having BlueTooth on at the same time as the WiFi connection going. With both on at the same time, at some point in the future the WiFi connection is going to hang, right up until BlueTooth is turned off again. Which means I can't use already-existing media remotes, like I do with my phone. I should probably comment on my experience with those at some point, too.

Anyway, you can buy loads of cheap USB-capable microcontrollers, which are very easy to write code for, and already have a variety of modules that should be useful.

The problem comes in that the vast majority of USB-capable microcontrollers use USB-to-serial-port chips, that cannot be told to act like a keyboard. And while the ones I'm using right now don't have those chips, they instead talk directly to the computer over directly-controlled pins (using a low-speed USB communications protocol), the libraries available for these modules can't actually handle the media control scan codes.

I'm currently conversing with someone on the forum for the brand of microcontroller I'm using, but we're not getting anywhere very quickly due to how vastly complicated the USB specification is. Hopefully I'll get somewhere useful sooner rather than later...

#4: FM Radio in old PC speakers

Before I bought my current set of Altec Lansing speakers, I'd previously had a couple of older PC speakers. Combine this with how difficult it is to find FM radios with digital tuners, and how cheaply you can find moderately decent ones from China, I now want to put a small, credit card sized, single board FM radio tuner module into a pair of PC speakers.

In theory, it would be as simple as cutting a hole into the front of one of the speakers, but the front side of the speaker won't hold the LCD screen in place (due to me fiddling with it over the time I've had it), and I'm currently trying to figure out (with my extremely limited experience) what exactly I want it to look like when it's actually built.

One problem, for example, is that, even with all the things I know will need to go into the "main" speaker, it won't be heavy enough to hold it against the simple act of pressing any of its buttons. I could add an extra heavy weight to the bottom, but it would be simpler to either mount the buttons so they're pressed downwards, or (as the module I'm using has its own buttons already attached) use levers to convert downwards pressure to sideways pressure on the existing buttons. Which is a very interesting challenge all on its own.

Another is that, given that it doesn't take all that much energy, I want the backlight to be on all the time. Which wouldn't be too much of a problem, except that the default LED colour it came with was blue, and I'd rather have almost any other colour. Do you have any idea how hard it is to solder wires directly to surface-mount LEDs!?

#5: Monitor Stand

Not everything on this list is digital and/or electronics, though this directly relates to a hardware thing. I'd picked up a random LCD monitor off the street a few months ago, and had to figure out how to squeeze it onto my desk, given that my desk here is stuck inside my bedroom's closet.
(this is a bad idea, don't do it. I no longer have a random place to toss things while I figure out how to store it!)

Anyway, I'd inherited a variety of pieces of plywood from my last grandparent to pass away, so was able to put my main monitor (which, it turns out, was too high for how high I sit in my chair) on a single roll of 3D printing filament (obtained from one of the two 3D printers I still haven't used for that purpose yet) and a piece of plywood. Ideally, I'm supposed to have added a leg to each side of the plywood platform already, but it's so easy to overlook (since I'm always looking at the thing above it) that I just haven't done anything about it yet.

Plus, there's the problem with the mousepad for my laptop intersecting with a corner of where the stand will go, so I haven't been sure how to proceed on that front yet. I have enough tools that I should be able to do it, it just takes effort to pull off.

I can't move my main monitor pretty much anywhere but where it's currently sitting either. It can't move left, as it's already slightly obscuring the secondary monitor in that direction. It can't move right, because I have two pencil stands blocking it (which are also being blocked by other things on the desk so they can't move to the right either), as well as the shallow shelf I have behind it on the desk. It can't move up because that would cause more neck strain. And it can't move down because the stand the secondary monitor sits on is a small fraction of an inch below its left edge.

Once the stand is built, I'll be able to move my desktop USB power supply under there, reconnect the LED underlighting that I had on the previous setup, and add a bit of extra storage under there.

#6: Small plywood box

Turns out, one of the dollar store chains in my area has "craft" sized plywood. Technically five-ply, though the outer two layers are paper thin, so effectively three-ply. One size is square, four-and-a-half inches per side, and not actually anywhere near square. The other is about seven inches long by not quite three inches wide, and both are five pieces for about two bucks.

The square ones are close enough to the right size for drinks coasters, so I didn't have much to do with the long, thin ones. Until I realized that I had a use for a small box to fit under the phone stand on my desk. Thus far, I'm storing things inside the stand, and when I'm charging my phone, the cable bends too tightly and/or takes up too much space on the desk in front, so if I stood it up on a small box, it wouldn't be as much of a problem.

Now, while I have the tools to deal with smaller pieces of balsa wood (courtesy of the passing of my grandfather who used to build his own RC planes) and larger pieces of wood (due to the mitre box I'd bought a while ago), I don't really have tools sized to this scale in the middle.

Fortunately, all I want is a butt-joint, not a 45° mitre-joint, but even then I'm more than a little nervous about this. I am going to see this every day, so any obvious mistake is going to be entirely frustrating each and every time I look at it.

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Anyway, that's just some of the things I'm working on. And forgetting about. There's probably lots more, but I don't remember what they are right now. If I had a master list of them, I'd want to work on all of them, but it's simply not possible. Plus, I'd feel ridiculously guilty that I'm not working on any of them...

I'm mostly just posting this for my own reference, but if it helps you guys, that would be great too.

Big Clive on YouTube dissects a lot of cheap Chinese electronics and posts the results online for others to see and learn from. Granted, it doesn't have to be cheap Chinese crap, as he does work for a large theatre-type company over in England, so sometimes he has to take large and ludicrously expensive theatre lights apart to see what went wrong and try to fix it, which is often as enlightening as his usual content.

Anyway, he once did a series of videos on Chinese "meteor" lights, or the type of icicle lights that actually look light raindrops are falling down the length of each icicle. The sheer complexity the Chinese engineers have been able to squeeze out of such inexpensive components is very impressive.

First, an explanation of how these work:
Everything you didn't want to know about Chinese meteor lights.

Second, how he was able to repair a damaged string:
Fixing a faulty meteor light.

Next, how you can make your own icicle/meteor lights:
Make DIY meteor lights with multiple effects.

And finally, a project he experimented with to get different types of effects out of a string of meteor lights:
Experimental meteor light software.

Why I'm posting this is for an idea I just had for an electronic game timer. Now, one disadvantage of using this technique is that it's only possible to have one LED lit at a time, but the major advantage is that you can control twelve discrete, single-colour LEDs with just three control lines from the microcontroller. This simplifies things a lot on the hardware end, and makes it even cheaper to run a lot of LEDs, but means you have to keep cycling through all the lit LEDs constantly. And because of that, it's not constantly lighting the LEDs, but flicking through them, so it's not going to look constantly lit.

The alternative is to use digitally-controlled LEDs, known also as NeoPixels or the WS2811(B). That would use only a single data pin for the entire string of LEDs, but adds a fair bit to the costs, though not as much if you buy unbranded ones.

The general idea of the shape of the timer is a pillar-shaped bar graph kind of affair, with the lit segments lowering down like sand until it expires. I'll be coming back to this idea later, I just want to get it down somewhere I can refer back to it when I have the time later.