hillexed

@[email protected]
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472 Posts
he/him
webbed sitehttps://hill.pictures
Show threadhillexedApr 13
The LED strip with its brains replaced works! Turns out the protocol just WS2811 so the example code worked first try! After installing ESPHome, now I have LEDs I can control from my phone. I love the future
Show threadhillexedApr 12

Let me go ahead and replace this with an ESP32 chip I can control...

Looks like there are only two pins that are important: an input to the button on the reverse side and an output to the LEDs. There are other pins broken out to a programming header, but I don't care about wiring them up because the seeed xiao has an USB port for programming already.

Show threadhillexedApr 12
Update: my plans to put an #ESP32 in there were foiled by... it already having an ESP8685 (an ESP32 variant) in there! But after a few hours of poking at it with esptool, I keep getting the error "Wrong boot mode detected (0x01)." 0x01 means the pins should be in the right configuration to let me reprogram it, but I suspect the manufacturer set an internal fuse to disable reprogramming it. Shame.
hillexedMar 25

Astronomy sidequest: woodworking!

A few weeks ago I broke the DIY table I built to polish telescope mirrors, so I added some more screws and rebuilt it. It must keep mirrors at elbow height during polishing, and is weighed down to withstand sideways forces from friction. I copied the truss design from the guide on https://stellafane.org/tm/atm/mirror-general/materials.html , but this rebuild uses two screws per strut for added rigidity. I have employed advanced metrology equipment (pictured) to verify its surface isn't tilted.

hillexedJan 24

It has been several months of assembling and tinkering and troubleshooting to get here, but my bath interferometer is finally working! Now I can feed these images of concentric circles into software and analyze the shape of my mirror down to tens of nanometers!

These pictures show a laser beam, split in two by a beam splitter cube, interfering with itself. The dark zones show regions where one beam travelled an integer plus a half number of wavelengths farther then the other beam, so when they add back together they're out of phase and cancel out. A linear polarizing filter on my camera I got helps equalize the brightnesses and make the pattern clearer. The resulting pattern can be interpreted almost like a topographic map of the mirror, where a single ring is all at the same "height" from my 3D printed testing apparatus.

#diy #interferometry #hillescopemaking

hillexedJan 13
The laser beams in my interferometer seem to have a dark stripe down the center that makes it very annoying to align. I think it's an issue with the laser itself, since even without the rest of the optics the laser outputs a weirdly off-center beam
Show threadhillexedDec 26
several hours of fixing my code and remembering how electromagnetic waves are constructed later, my simulation works!
Green means strong electric field, red means strong magnetic field. Yee
hillexedNov 26

A few replacement parts later, it's interferometer time!

This is a Bath interferometer that splits a laser into two parts, reflects off a mirror, and then recombines to make an interference pattern. The overlap of those two circles should show an interference pattern of stripes across it which shows me a topographic-like map of the mirror's height in units of 600 nanometers.

hillexedOct 26, 2025

It's very hard to aim a telescope with its zoomed in view. I got this finderscope (a smaller, wide field telescope) for $30 used, but it sat on a shelf for a few months. It took a few iterations, but I finally designed a mount that allows my 8" scope to hold both my PiFinder and the finderscope at the same time!

#hillescopemaking #diy #astronomy

Show threadhillexedOct 24, 2025
Interferometer time is paused :(