The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Science

If you measure something often enough, it becomes science

Cheap WS2812 LEDs: Leak Tests vs. Failures

Applying the Josh Sharpie Test to three defunct WS2812 LEDs produced one failure:

Failed WS2812 LED – leak view 2

The other side shows where the ink stopped seeping under the silicone:

Failed WS2812 LED – leak view 1

I don’t know if I melted the side of the LED or if it came that way, but, oddly, there’s no leakage on that side.

This LED matches the layout of Josh’s “crappy” LEDs, as does the entire lot below, although I suspect that’s more coincidence than anything else; there aren’t that many different layouts around.

Flushed with success, so to speak, I ran the Sharpie around all the unused LEDs from that order:

WS2812 LEDs – leak test

I tested the process on the three LEDs in front, then wiped the ink off with denatured alcohol.

A closer look shows the ink all around the silicone-to-case border, with plenty of opportunity to seep in:

WS2812 LEDs – leak test – detail

After wiping the ink off, none of the 31 unused LEDs showed any sign of poor sealing.

I haven’t been keeping good records of the failures, but right now I have twelve functional WS2812 LEDs attached to various glass doodads. That leaves 7-ish failed LEDs out of the 15-ish with long term use (not counting four recent replacements).

In round numbers, that’s a 50% failure rate…

I should wire up the remaining sheet of LEDs as a test fixture, let them cook for a while, and see what happens.

2017-02-20
Monthly Image: Turkeys in the Trees

A turkey flock forages through the bottomlands along the Wappinger Creek and, at night, roosts in the trees at the far end of our driveway:

Roosting Turkeys – visible

I’m a sucker for that moon:

Roosting Turkeys – visible

It’s rising into the eastward-bound cloud cover bringing a light snowfall, so we missed the penumbral eclipse.

If you’re counting turkeys, it’s easier with a contrasty IR image:

Roosting Turkeys – infra-red mode

Mary recently counted forty turkeys on the ground, so that’s just part of their flock. I think their air boss assigns one turkey per branch for safety; they weigh upwards of 10 pounds each!

Taken with the DSC-H5 and DSC-F717, both the the 1.7× teleadapter, hand-held in cold weather.

Searching the blog for turkey will turn up more pix, including my favorite IR turkey shot.

2017-02-15
Monthly Science: WWVB Reception Sample

Further results from the SDR-based WWVB receiver:

60 kHz Receiver – preamp HIT N3 Pi3 – attic layout

Seven hours of mid-January RF, tight-zoomed in both frequency and amplitude, from 0350 to 1050 local:

WWVB waterfall – N3 – 2017-01-24 1050 – composite

The yellow line of the WWVB carrier comes out 2 ppm high, which means the local oscillator chain is 2 ppm low. We know the WWVB transmitter frequency is exactly 60.000 kHz, translated up by 125 MHz to the N3’s tuning range; you can, ahem, set your clock by it.

The blue band marks the loop antenna + preamp passaband, which isn’t quite centered around 60.000 kHz. Tweaking the mica compression caps just a bit tighter should remedy that situation.

Given that input, a very very tight bandpass filter should isolate the WWVB carrier and then it’s all a matter of fine tuning…

2017-02-01
ATX Lithium Ion 18650 Cell Capacity

The 2016-11A and 2016-11B cells produced the overlapping red and green curves, with the gritty section due to crappy battery pack connections:

Li-Ion 18650 cells – ATX prot – bare – Ah scale – 2016-12-17

The lower curve comes from an old unprotected cell harvested from a defunct media player and retrieved from the to-be-recycled pile.

I picked 1 A as a reasonable value for their intended use in flashlights and maybe a helmet camera. Unlike some other cells in the recent past, these deliver 3.0 A·h, reasonably close to their rated 3.4 A·h capacity at a (presumably) lower current.

Replotting the voltage vs. energy delivered doesn’t show any surprises:

Li-Ion 18650 cells – ATX prot – bare – Wh scale – 2016-12-17

The voltage declines more-or-less linearly, without the relatively flat discharge curve for smaller cells, which explains why the J5 V2 flashlight becomes seriously dim after a few hours. On the upside, that allows a reasonably accurate state-of-charge display.

Assuming the Sony HDR-AS30V camera burns 0.1 W·h/min while recording (which is a fancy way of saying it dissipates 6 W), then it should run for (10 W·h)/(0.1W·h/min) = 100 min from one of these cells fitted as an outrigger. The best of the NP-BX1 cells for the camera delivers something like 90 minutes from a measured capacity of 4 A·h at 500 mA; I don’t know what to make of those numbers. Perhaps the camera runs the NP-BX1 cells below the 2.8 V cutoff I’ve been assuming?

2017-01-02
Blog Summary: 2016

Page views for 2016:

Blog Page Views: 2016

That works out to a bit under 1000 page views/day of purely organic traffic.

As always, way more people than I’d expect come here with plumbing problems. On the upside, much of the bedbug saga has fallen off the trailing edge of the wedge; life is good!

2017-01-01
Maxell CR2032 Lithium Cell: Early Failure

The Hobo datalogger buried in the dirt under the patio kvetched about a low battery, which produced this surprising result:

Maxell CR2032 cell – early failure

Cells from the same lot have been doing just fine in the other dataloggers, so I hope this is a one-off weak cell and not the harbinger of another run of dead cells.

2016-12-26
Satco PAR30 LED Floodlight vs. Halogen

I replaced a dead 75 W halogen PAR30 bulb over the kitchen sink with a Satco S9415 LED bulb that was, at the time, advertised as “75 W equivalent”:

Satco S9415 PAR30 LED Bulb – specs

It’s noticeably less bright than the surviving halogen bulb, which is what you’d expect when 950 lm goes head-to-head with 1100+ lm (based on casual searching), but with a similar color temperature and beam pattern, so it’s Good Enough. I should have bought two and converted the halogens into glass sculptures.

The difference between the 22.8 year Life and the 3 Year Warranty always seems amusing. The warranty requires returning the bulb, so that’s about useless …

2016-12-10