Some photographs of lightbulbs

Written 2023-04-21

Recently, one of my high-beams burned out. It had been a bit, so I replaced both high-beams and both headlights. And then I took a few pictures.

This was my kitchen table setup of Leica StereoZoom5 and Canon 7D with a passive(no optics) lens adapter.

This high-beam bulb had been in service a bit long. What does it look like inside?

another old bulb
I had trouble aligning everything in focus so this is a composite. I like the little clamps holding the filement to the support wires. It's pretty wild how the filament is scarred from years of heating and cooling cycles. Also note how metal seems to have jumped from the filament all the way to the left support.

old bulb
Here's a different old filament.

This is the one that burned out. The filament isn't connected, and there are two patches of metal sprayed onto the glass. Lets take a closer look...

broken joint
This is where the metal failed. Strange how one side looks like a solder ball, but the other follows to a point. They must be made from different materials.

This is the other end of the filament. It's coated in little metal fragments too.

glass is fun
This is a fun shot I found while trying to zoom and focus the camera on the bottom of the filament. I liked how the light flows around through the glass. Because I have a cheap mechanical-only camera adapter, changing the zoom wildly changes the focus so I have to adjust both together. I don't often take photographs through my microscope though, and optical adapters are much more expensive.

new bulb
Finally, this is what a new bulb looks like. I didn't get a good photo, but the supporting wires appear to be pressed flat, then folded around the ends of the filament, rather than the little clamps of the other bulbs.

Neat unit conversion trick

Written 2022-12-11

Tags:Ham Radio 

Amateur radio requires a multiple-choice test for each new grant of operator permissions, each granting a larger amount of spectrum and capabitilies. You are allowed a calculator, but it's possible to get by with pen and paper or memorization. One question that comes up on the tests fairly often is conversion between band names and frequency band edges. If you've memorized the band-edge frequencies, you're all done. But if you haven't, you can rule out most of the possibilities from the answer set with a simple relationship.

Though I usually use a unit-aware calculator most days, that's not available on the radio tests. One simple math trick I've found I enjoy is expressing relationships in particularly useful units. The basic physics relationship we have is wavelength * frequency = speed of light. On the test, wavelength is expressed in meters, and frequency in MHz. If we represent speed of light not as 3e8 meters per second, but 300e6 meters per second, or 300 megameters per second, we can rearrange our equation without units as: wavelength = 300 / frequency or frequency = 300 / wavelength, which feels a little easier to work out.

New Neighbors 2

Written 2022-12-11 hosting is back up at HappyBee host, transition was quite uneventful. Here's the new neighborhood: maintenance

Written 2022-11-23 hosting has been hosted by Nalan Nijesh's HappyBee Host since December 2017. Outside of one hiccup when my VM's host ran out of disk space, it's been quite reliable, and low priced.

Part of what made this cost effective is a container technology called OpenVZ containers. HappyBee Host is now transitioning their users off OpenVZ to KVM, which they've also supported for some time.

Expect this site to go down a bit in the coming weeks.

Modifying a 5 foot Lowe's poseable skeleton for cycling

Written 2022-10-23


So, you have a spare tandem bicycle but no one to ride halloween with you? Simply add a skeleton!


Skelly is a five-foot poseable skeleton from Lowe's. However, their joints are designed to be poseable, and make a loud clicking noise when adjusted - not ideal for continuous operation, and would probably wear out quickly. Here's the joint mechanism:


There are a few different variations on this theme throughout their body, but they all share a spring-loaded toothed gear(or gears) sprung into a fixed gear that takes a fair amount of torque to snap into the next position. This creates a number of positions where the joint is stable. Ends of the joint are held into the next bone either by 4 plastic posts(top of this joint), or by a plastic stick-out(bottom of this joint). Here's an assembled view screwdriver replacing bolt):


Here's the hip(a one-sided leg to hip joint):


Here's the ankle(lower leg reaches over both sides of ankle joint):


Disassembly notes: Each joint is held with a phillips machine screw and nut. Since the joints are spring loaded, don't do it over a skeleton-colored carpet. Try to hold or at least cover the joint assembly as you remove it. For example, this spring-loaded ankle:


Modification notes: We only need to flatten the gear-teeth to achieve smooth motion. I used a box cutter. Some of the pieces are easy enough to cut on directly. Others you may find easier to bolt half the joint on to one end to hold it still while cutting. The plastic is fairly strong, and it took me several passes to achieve my desired results. The gears don't need fully flattened, but they should be mostly parallel to each other, and at least 2/3 of thickness of the teeth should be removed.

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