Linear Clock: Solar | Hacker News Reader

Linear Clock: Solar

jmw.name

71 pointsfirloop17 comments

Cool project and kudos to them for working through the necessary math to calculate sunrise and sunset.

You can see a few more pictures on the "Shop" page [0]. They are hidden behind the "View product"-button. I've extracted a few links and modified them to link to larger images [1-3]. The power supply is connected via a barrel connector as can be seen in image [3]. I guess I would have used a USB power supply instead, just because of their ubiquity.

[0] https://jmw.name/shop/

[1] https://cdn.shopify.com/s/files/1/0557/1513/5639/products/li...

[2] https://cdn.shopify.com/s/files/1/0557/1513/5639/products/li...

[3] https://cdn.shopify.com/s/files/1/0557/1513/5639/products/li...

Or a small solar cell?

I actually used a USB connector on the previous Nixie-tube based version. It's harder since there aren't as many panel-mount options for the USB connector. You have to design the circuit board around abutting the enclosure wall. This makes sense in an injection molded or unibody construction, but less so with a wood box like this.

You're also potentially limited by the USB spec on current draw. There are ways around this, like ICs that will detect if you're connected to a charger or a data port. The barrel connector is also quite ubiquitous and I designed the power entry to work across a wide range of DC power adapter voltages.

Thanks for the explanation, that makes sense.

I have also discovered the previous version now ([0], if someone else is curious as well) and will have a look at it later.

[0] https://github.com/jmwilson/leave-time-behind

Looks great. The use of a CNC seems a bit overkill, when it looks like a trim router + template would have done the same job with zero CAD modelling required. Unless I'm missing something.

This is cool, but I think I'd have done the design just a little differently. The author noted that seeing when the sunset was had some effect on his perception of day length. I think I'd design a similar clock to have sunrise and sunset markers, and the continuous bar would show the position within 24hrs. That would make me even more aware of which parts of the day I was using, and their relative durations.

I was thinking this as well. Having the start and end of the bar be midnight, with two dots representing sunrise and sunset, is way more intuitive to me.

Reminds me of this article: https://www.hodinkee.com/articles/the-eerie-beauty-of-the-ap...

I thought about that, but I wanted to ground the display in the natural cycle of the day. Once you introduce wall-clock time into the design, there are at least two problems that need solving:

1) what's the timezone? 2) what about DST?

The first is quite complex and requires knowing more than just lat/lon. Dates of DST also do change over time according to policy. The only solution I saw for these would to go full IoT so it could talk to NTP servers or have a control interface, and that would ruin the plug-it-in-and-it-just-works minimalism I was going for.

Entirely fair set of decisions! Thanks for the reply.

I love this project, and this is meant as an honest question rather than criticism: has the creator given any thought to FCC certification?

My understanding is that in the US, this device would be classified as an "unintentional radiator". If you want to sell it as a finished product to consumers, then you're legally required to get it tested by an ANSI C63.4 compliant lab to ensure that it meets the legal limits for RF emissions into the air and the power grid. AFAIK the typical cost for a round of testing is >US$1000, and it needs to be repeated if you make hardware changes of pretty much any kind.

I've occasionally considered making and selling projects kind of like this one as a hobbyist, but it seems like the cost of compliance testing means that you have to be reasonably sure that you'll sell at least a few units, or else you're just throwing money away.

It's a good question and something I'm looking into as I consider the idea of selling them. It's something that has to be approached in the context of other changes (like BOM optimization) for larger manufacturing.

I've studied SMPS design and am not totally oblivious to conducted and radiated EMI issues. I took several considerations in the project like analyzing current loops and taking near-field measurements on a spectrum analyzer. However, what ultimately matters is what happens in the testing chamber.

Gorgeous! I have a soft spot for an unusual clock design or orrery. I've been trying to learn Adafruit's NeoPixels for a quasi-similar project and the world of soldering and wiring is way different than firing up a new Git repository!

Wow, great project!

Beautiful.

What is the blue dot for?

> The sunset indicator was immediately interesting. Days are longer in the summer and shorter in the winter, but I never quantified it for myself. How might I plan my day differently with a clear indicator of the balance available between daytime and nighttime hours?

Ah, I had misunderstood the section on wanting to start at sunrise, and interpreted it as a bar starting at sunrise and ending at sunset.

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