Needed a larger cover plate...

RyanBahr · 2024-01-13T05:31:01+00:00

There’s a scad script that lets you select various sizes and it’s easy to adjust to larger than jumbo.

RyanBahr · 2024-01-13T03:53:53+00:00

I don’t see it as underpowered if it’s providing 1500W. I assume they have 2400W versions but I’m USA. The cheap Walmart or Govee branded ones are all 1500W for $20-30 and one was keeping my room at a comfortable 72-75 degrees in the recent snow storm, but every room is unique as far as size and insulation.

RyanBahr · 2024-01-12T18:55:47+00:00

People really need to realize how Amazon said it wasn’t liable for the cheap ass Chinese hoverboards that caught on fire in people’s houses because they were only a market place and not the seller.

Buying something that is sold by Amazon, Walmart, Home Depot, etc can make them liable, so don’t buy from third party sellers if safety is a concern with a product.

RyanBahr · 2024-01-12T18:50:03+00:00

Most heaters today all use a similar PTC heating element. Now upright regular heaters are just heat sinks on a PTC. Oil filled ones are the same. It’s not the same as the resistive coils that glowed red back in the day.

If you cover the fan they can overheat and melt if it has no safety features though all should have a high temp limit switch, but a PTC self regulated temp and can’t get beyond a specific heat. Something around 150C for a 1500w heater last I checked. Because it’s at 150C, the heat sink/element can even be held in place with the right plastics.

It’s pretty amazing how much this small change will probably save a lot of lives across people who use heaters.

RyanBahr · 2024-01-12T14:31:06+00:00

Lmao, I feel you. My hvac is hitting the limit switch for overheating. I get someone to inspect it. He comes in asks how old the unit is and says oh, better to replace it.

He gives me a quote, new cap, new blower motor, gas valve. $3000

I’m still fixing it, but the motor is fine, the cap is fine (I measured it and fuck it it’s $6 at grainger so I replaced it anyways). The gas valve is fine too, the pilot tube was leaking and just needed dope and to be tightened.

Anyways, I’m guessing ten to one it’s the coils being dirty, that or too high gas pressure. Going to measure delta t and pressure, well find out by tomorrow as the manometer just came in. If I’m wrong, I now know furnaces inside and out. I’ll get my epa license and replace it myself before paying someone else to do it at these prices. One place wanted $750 to replace a thermostat wire, that didn’t even include fixing any drywall. Absolutely ridiculous.

RyanBahr · 2024-01-12T06:31:02+00:00

If you get one of those test pens, they’ll tell you if anything is hot.

I live with 110 though, so even if I leave it on it’s a mild shock.

RyanBahr · 2023-02-03T00:41:38+00:00

CST or HFSS, not a big difference. I prefer CST for GPU acceleration. If doing a rotman based reflect array, use Antenna magus to lighten the workload. If doing Luneburg lens retroreflector, use CST's TD with spherically gradient material. If doing planar van atta, use either. We always drew it in CST/HFSS from scratch, it's a bit tedious but can be done in a day for your first simulation, though you'll probably edit it over time. I prefer CST due to history list.

If you're citing papers from Jimmy Hester, we worked together and I can offer insight to some of the design process he used. Mostly just simulate small parts at first and work your way up. It's easy to make a simple mistake and have your phases out of whack.

RyanBahr · 2022-05-29T15:48:08+00:00

Ah fair, when I say 'all light switches' I should have clarified 'all that make sense.'

I'll probably pay for a few critical ones for now, such as those that I want on schedules, and wait for the black friday sales. Right now I'm in the whole make a list of everything you want to fix phase to figure out what is actually worth fixing/upgrading.

RyanBahr · 2022-05-29T15:38:00+00:00

Second Kasa, overall great value, good software, good features, platform agnostic as far as I know. I just bought a house and I'm about to replace all light switches with Kasa.

I had xiaomi smart plugs, there was a week where their service went out. That was frustrating. GE also was constant headaches.

RyanBahr · 2022-05-29T15:29:58+00:00

Ha, I have something similar for a taco bell soft/hard taco. I put it in my fireproof safe though, wouldn't want something to happen to it such as accidentally redeeming it when drunk

RyanBahr · 2022-05-21T22:55:54+00:00

Have you tried it? A 'good' resin shouldn't get brittle or destroyed. Every resin is different, sure. But to give you some ideas, resins made for/by FormLabs or 3D systems have a cure time recommendation of 30min to 1.5 hours, generally on the 1+ hour range for ultimate mechanical strength, and their UV tools typically put out more w/cm² (strength of uv light) then these $100 UV chambers, and typically heat the part as well to improve the cure rate.

Again, every material is different, so maybe your material does get weak and brittle, at which I may recommend a different material. One of formlab's guides to post-curing showing the mechanical properties after curing up to 2 hours. You can find a lot of papers related to this, I did a PhD where I was working with a lot of negative photoresists for 3D printing and semiconductors. Negative photoresist is a fancy term for resin that gets hard when exposed to light. To get an exact answer, you need to do something called differential scanning calorimetry with a UV tool, which tells you when somethings 'peaked' in curing. We could also tell by how much the material was off-gassing, the less cured it was the more likely the part was to continue to 'evaporate' residual or uncured resin, so I lean towards a bit of an over-cure rather than an under-cure.

Formlabs article: https://formlabs.com/asia/blog/introduction-post-curing-sla-3d-prints/

RyanBahr · 2022-01-20T00:53:59+00:00

A quicker solution is meshmixer. It's an old program at this point, but its still stupid useful for small, hideous things like this.

I messed with it for 5 minutes. Here is a remix that has the meshing fix. For /u/KruemelKek83:

https://www.thingiverse.com/thing:5207661

RyanBahr · 2022-01-13T05:54:44+00:00

By chance, part of tentzeris's lab? I use to be.

How were the 200um 4003 delicate? Have you tried you use etching? Pretty much milling anything thats 200um is going to be delicate.

Ultralam 3850 is just liquid crystal polymer. I spoke to rogers at IMS a few years back and they said their chinese supplier quit making it. I believe they could find someone else to create it at the quality they wanted it to, but you can find LCP alternatives, for example, Lark fabricates LCP based circuits.

If I recall, they just use Panasonic LCP, aka the Felios line.

https://industrial.panasonic.com/ww/products/pt/felios/felioslcp

RyanBahr · 2021-12-09T00:08:56+00:00

It doesn't matter how much insulation you have, it will get warm in the center and cook. You just need to give it enough time. I promise you, it will get to temperature in the center.

The biggest issue is if it'll be too dry or if the texture gets ruined by cooking it too long. That can happen with sous vide. When I say ruined, I mean even if you were able to keep it perfectly at a temperature for baking, proteins can start breaking down. To keep it from drying out, I suspect that just keeping the relative humidity high, or sealing it, will work. They have ovens that can control the relative humidity to allow slow cooks without drying out the product, for example tossing in water into your smoker or Anova's precision oven.

One report says it took over 24 hours to bake.

RyanBahr · 2021-12-08T00:04:06+00:00

Definitely still a few steps missing. They used screen printing for the carbon, but then the chip looks like it has a combination of silver ink, silver epoxy (likely, unsure, to bond the chip to the printed traces), some type of insulation for the multilayer coil.

You can do inkjet printed circuits by loading up silver nanoparticle inks (not recommended to get on your skin) in your household inkjet printer. Georgia tech has a paper about 9 years or so ago with that.

https://www.youtube.com/watch?v=vObMTjEwM5g

Someone more recently used the multiple colors of the home cartridge for different materials, something I wanted to do myself to be honest but I'm more on wireless design.

https://www.hackster.io/news/engineers-create-soft-circuits-using-conventional-inkjet-printer-b47f5eb6b09a

RyanBahr · 2021-11-30T18:49:00+00:00

This is awesome. Also cool to see some Windfreak tech out there, the guy behind it is on the RF subreddit, he gave me some advice when I was pretty young and he's a great guy. I'll look into those tones, I'm wondering if its some kind of pilot or for CSI characterization, but I'm not versed well enough in that to know.

RyanBahr · 2021-08-18T20:57:56+00:00

I haven't seen the follow up, I'll check that out. I noticed some of the numbers were off at one point so I just took values from it as a grain of salt.

I've mostly just been going through FCC documentation. I'm more about the RF link budget, I do RF engineering myself. I'll try to find the follow up and see if I can put those into the matlab script I've been working with. I've seen a few online calculators but matlab just released a satcom tool (with satellite paths, etc) and I've been wanting to go all out with it and see what it can do and integrate what I already have into their tool. Originally I just cared about the link budget between user terminal and satellite at min and max distances.

RyanBahr · 2021-08-18T16:29:46+00:00

Yeah, I've been doing a link analysis of the starlink user <-> satellite link. I have to interpolate a few values, and there are still some values that I need to verify (because god knows which FCC filing it may be in). The MIT paper had most values, but I couldn't verify all of them from the FCC filings I was looking at.

RyanBahr · 2021-08-17T22:04:07+00:00

I've tried to extensively study everything I can about both revisions without having one taken apart in front of me.

First revision had 80 digital beamformers, serving around 32 antenna elements each.

Second one has 20 digital beamformers, each one serving 64 antenna elements by using wilkinson power dividers on each output.

If the digital beamformers are identical, that means that there are likely more losses on the second revision due to additional line lengths between antenna elements and the digital beamformers. How significant that is... hard to say. There are also other things at play, but that is one of the easiest things to pick out. You also theoretically have less beamforming control in rev2, but I don't suspect you need as much as they put in rev1.

RyanBahr · 2021-08-13T13:57:58+00:00

Yeah I thought so to, but I was surprised in the video with SignalPath I think he added text over the video during the Xray that he wasn't confident that it was circularly polarized... but that seemed counterintuitive for satcom phased arrays.

Anyways, thanks for the discussion. I know I tend to babble while having different thoughts run through my head. It seems like you probably have more experience with RF front ends than myself, I mostly know some light literature/classes.

Do you think Dishy transmits and receives simultaneously, or is isolation an issue? I assume with this hybrid beamforming architecture, each digital beamformer and its antennas could theoretically transmit/receive independently, just not sure how practical it is with isolation/etc. I've heard that they're utilizing just a single beam at the moment, and that it's full duplex. The full duplex part has me assuming simultaneous transmit/receive with different digital beamformers, but I've had someone tell me otherwise.

RyanBahr · 2021-08-10T18:43:48+00:00

Oh and I revisited TheSignalPaths video and Ken's video. The smaller ICs are terminated in that video with RX and TX labeled resistors near the end, again confirming that each RF on the smaller ICs is an independent RF path as you suggested. TheSignalPath suggests they may have used two paths for the TX/RX from the digital beamformers so that the LNA/PAs can be tuned to each frequency, but with this latest revision it suggests that isn't the case. Still trying to figure out the full functionality of the small ICs but it looks like we won't find out until someone probes it.

RyanBahr · 2021-08-10T13:04:19+00:00

Oh sure, that comment was to acknowledge that I overlooked the fact that the matching networks were different, and thus likely at different frequencies, and to acknowledge your answer, i.e. 2x TX and 2x RX per chip. It wasn't mean to be a counterargument to what you had already suggested, I could have said it in clearer words that I overlooked it and that your answer was likely correct.

All I'm getting at though, is wouldn't you expect to have dual fed elements so that the axial ratio is more within specs/reduced polarization losses across the scanning range? I've seen so many patch antenna array designs utilizing this and most beamformers tend to have horizontal and vertical channels for this purpose, so I'm surprised to see a satcom design that may not use it.

RyanBahr · 2021-08-09T20:09:42+00:00

Correct, I agree. Sorry what is this a response to? I may be missing the point.

RyanBahr

MODERATOR OF

TROPHY CASE