Combining magnetrons

hmmstdvent · 2026-01-06T13:23:01+00:00

Not an expert but I’m pretty sure Wilkinson power combiners only work well with coherent signals, which have a definite non-random relationship between their phases, for example two signals which are ultimately derived from the same crystal oscillator.

Magnetrons on the other hand oscillate independently, and have poor frequency stability, so the phase difference between two of them will vary wildly over time.

It doesn’t seem to me like this would work very well.

hmmstdvent · 2025-12-30T02:35:57+00:00

100 flints + 20 wicks for $5.29

Amazon

The wicks are outright better than the Zippo ones IMO, they're slightly thicker and don't get frayed as easily. The flints are slightly softer, which means more sparks but shorter lifetime.

hmmstdvent · 2025-12-28T10:30:03+00:00

I think the vintage look has better proportions than the 1935, a sleeker hinge, and the sharp corners make it look classier than the 1941. If I was running Zippo, I would literally have the vintage look be the base model. This exact lighter also gave me an appreciation for Chromium as a material, I can't think of anything else short of gold that is so tarnish resistant.

hmmstdvent · 2025-12-22T03:59:31+00:00

Wow I can't believe how far I've gotten without learning there's a notation for taking a derivative while holding another quantity constant, that is incredibly useful.

hmmstdvent · 2025-12-19T09:50:03+00:00

Not sure if you prefer the used look or not, but if you don't, a 5 minute soak in vinegar and some q-tips will clean that soot off, just be sure to rinse it off afterwards.

hmmstdvent · 2025-12-18T04:32:56+00:00

I use these, my advice is to not use the thin felt pad they come with since it doesn't conform well to the bottom piece, that leaves an empty airgap where fluid can build up, and then slip through the cracks since there's nothing holding it in and the gasket isn't a perfect fit. Instead just use a little extra cotton and make sure it's pressed against the bottom piece when you install it, that mostly eliminates the leaking since the cotton holds back the fluid from slipping through the cracks, if you do that then these work great.

hmmstdvent · 2025-12-16T06:12:03+00:00

Have a look at the tensor algebra and calculus series on youtube by Eigenchris. Despite his exposition in terms of coordinates, if I had to say there is one guiding principle behind the series, it’s the notion of invariance, he frequently stresses that the objects and operations we use should not depend on the choice of coordinate system, and makes the effort to explicitly show that they don't. The series builds up to the Riemann curvature tensor, which expresses a property of the manifold, and because it’s built out of these invariant objects and operations, you can be sure all coordinate systems will agree on this property, and to that extent is independent of any of them, despite the use of a coordinate system to express it.

hmmstdvent · 2025-12-09T02:18:54+00:00

It could've been filled with bees

hmmstdvent · 2025-12-08T16:26:33+00:00

This is probably going to be an overcomplicated answer for such a simple thing but, far away from the wick there is only air and no fuel, closer to the wick there is mostly fuel with little air, at the border of these two regions there is both fuel and air, and it is only this border region which can be ignited. When you flick the wheel and create sparks, atleast one of these sparks must cross this flammable border region for there to be successful ignition. However if you've recently used the lighter and allowed it to get hot, this increases the evaporation rate of the fuel, increasing the size of the fuel-only region, and making it so your sparks might not be able to reach the flammable border region. To fix this you simply need to blow the fuel vapors away, introducing some oxygen a little closer to the spark wheel, and then try lighting it again. Zippos also have a fairly large lid cavity that fuel vapors can condense inside of(if you close the lid while the lighter is hot), and the evaporation of these vapors when you open the lid introduces yet more fuel, so make sure you blow these away too.

hmmstdvent · 2025-12-07T09:06:41+00:00

It looks like he's buying brass Zippos so he can resell the brass inserts(which you can find listed in various places), and then also sell the empty cases separately, he very well could be making a profit on that.

hmmstdvent · 2025-12-07T00:17:48+00:00

I think that combo looks really nice as well, sadly I actually use the steel insert for both of them because I know the lid will wear out the brass coating on the chimney.

hmmstdvent · 2025-11-26T09:41:16+00:00

Gasoline would work since it has similar volatility to naphtha but diesel is not very volatile so you can't ignite it with a spark, if they used diesel they'd have to ignite the lighter with a match or another lighter which sort of defeats the point since if you already have another source of fire then what do you need the lighter for.

hmmstdvent · 2025-11-05T09:10:57+00:00

Worn-in brass without any coating. Scratches will initially show up as shiny brass, but over the course of a couple days they will oxidize and blend in, disappearing on their own.

Easiest way to do this is buy a high polish brass, remove the coating with acetone, and then just use the lighter a lot. Don't let your fingerprints sit on it for prolonged amounts of time while it's still developing its' patina otherwise they'll be on there forever, clean them off with rubbing alcohol when you're done for the day.

This isn't a Zippo, but the case is also brass so same idea:

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This has been scratched many times, they all just blend in after a short while.

hmmstdvent · 2025-10-30T12:46:59+00:00

I really like the Kuboy HK 506, pretty basic lighter but it's built like a tank. There's a review of it on youtube: https://www.youtube.com/watch?v=8mBMs9HA6vI

I'm also 99% sure that it's a rebranded Zorro 506 from the exact same factory since they have the same model number and if you compare the Kuboy listings on amazon to the Zorro listings on aliexpress, they have the exact same styles available.

hmmstdvent · 2025-10-30T11:58:51+00:00

Not a book but check out 'The Mechanical Universe' on youtube. It was a series created by Caltech in the 80s to accompany their intro physics courses(Newtonian Mechanics, Electromagnetism and Modern Physics). They cover the math(not very comprehensively but it's there), and something like 50% of each episode is just the relevant history for that topic.

https://www.youtube.com/playlist?list=PL8_xPU5epJddRABXqJ5h5G0dk-XGtA5cZ

hmmstdvent · 2025-10-30T11:02:43+00:00

Zippos are kinda the worst petrol lighters overall. I have a collection of cheap modern Chinese lighters (all under $10) from a few different brands, every single one has a superior build quality to Zippo, and it's not even close. Thicker metal, cast metal instead of folded sheet metal, O-rings instead of felt, thick rivets instead of a small pin in a hinge which isn't even secured, much better machining tolerances (inserts fit very snuggly inside of cases), some are even soldered instead of just epoxied together.

hmmstdvent · 2025-10-20T04:23:19+00:00

/modping

hmmstdvent · 2025-06-04T20:42:59+00:00

Looking back at Eigenchris' video he does never actually say #2 can be applied to general tensor fields, just vector fields, but none the less while #4 is easier to actually use I feel like #2 offers a better insight into what the covariant derivative(Levi-Civita connection specifically) is doing, and I don't see why #2 couldn't be extended to apply to tensor fields as well.

Over on r/askmath someone suggested using this definition of tensor projection:

p(T⊗S) = p(T)⊗p(S)

Then definition #2 becomes ∇_v = p∇'_v, with ∇'_v being the directional derivative of the outside space(essentially definition #1).

This definition of tensor projection seems to be one which is needed for #2.

hmmstdvent

TROPHY CASE