Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
It’s one of the few Underwriter’s Knots I’ve ever seen in the wild. Many recent (i.e., built in the last half-century) lamps pass the cords through a plastic clamp or depend on simple bushings, with some just ignoring the problem.
This anonymous lamp sports the usual Made in China sticker, but also features a genuine-looking UL sticker complete with elaborate holograms, so it may well have been sold by a reputable company. IIRC, it came from a trash can in a Vassar College hallway, back when in-person meetings were a thing; perhaps Vassar required known-good electrical hardware.
Just before the turn of the millennium, I bought what turned out to be a never-sufficiently-to-be-damned HP 2000C inkjet printer that served as my introduction to refilling inkjet cartridges. A few years later, a Canon S630 printer joined the stable and worked fine for perhaps five years before succumbing to a printhead death. An Epson R380 that might have cost fifteen bucks after rebate took over, drank maybe a gallon of knockoff ink through a continuous ink supply system during the next thirteen years, and finally suffered progressive printhead failure during the last year.
Something recently changed in the inkjet market: Epson (among others) now touts their “Ecotank” printers featuring large internal reservoirs refilled by 70 ml bottles of color ink priced at perhaps 20¢/ml, obtained direct from Epson via Amazon. They proudly note you can save 90% off the cost of cartridges (“Kiss Expensive Cartridges Goodbye”), without mentioning how their previous extortionate cartridge business made that possible. Of course, Ecotank printers cost far more than cartridge-based printers, but that seems reasonable to me.
Because the ink bottles fit neatly into the printer through a push-to-flow valve interlock, I can finally retire this relic:
Inkjet refilling towel
That’s maybe fifteen years of accumulated splotches.
Harvesting a line cord for a widowmaker test setup revealed its inner secret:
Mystery not-copper wire – as found
The conductors are as thin as I’ve ever seen in an AC line cord, with 0.5 mm² = just under 20 AWG. The color code doesn’t match USA-ian standards, but neither does the labeling, so I’m not surprised.
If the individual strands seem unnaturally straight, they are, because they’re made of (presumably) copper plated on a (presumably) metallic core. Here’s what they look like after bending them sharply around my fingernail:
Mystery not-copper wire – bending
Wonderfully springy, utterly non-magnetic, and surprisingly durable.
Scraping the 0.02 mm strands with a sharp blade reveals a silvery interior, so it’s (presumably) not copper-coated plastic. Aluminum springs (ahem) to mind, but I’d expect tiny aluminum strands would snap (or at least deform) when bent and erode quickly when scraped.
Each wire measures about 1 Ω / m from the plug (a convenient 40 inch = 1 m away), which is the resistance you’d get from a single hair-fine 5 mil = 0.13 mm strand of 35 AWG solid copper. An 18 AWG aluminum wire would have the same resistance as a 20 AWG copper wire, both of which should be 32 mΩ / m: a factor of 30 less than this crap.
A hank of the wire goes into the Box o’ Springs, in the event I ever need a tiny straight spring rod; you definitely can’t wind this stuff into a coil! It might be fine enough for a crosshair / reticle, at least for crude optics.
Some suggested 151-1032-00 replacements obviously won’t work, such as Tekwiki’s 2N5397 single JFET. Bonding a pair into a single heatsink might suffice, but two separate cans generally aren’t identical enough for the purpose.
Curiously, Tekwiki also lists the 2N5911 as a 151-1032-00 replacement, which (being an actual dual JFET) looks more promising. This agrees with another cross-reference, although the “Sim[ilar] to” suggests considerable caution.
The actual Tek 151-1032-00 can in its heatsink, oriented with the tab at the top (just visible to the right of the heatsink fin):
Tek 151-1032-00 – top view
Testing one side (with the tab on the left):
Tek 151-1032-00 test side A
And the other side (tab still on the left):
Tek 151-1032-00 test side B
A picture being worth a kiloword:
Tek 151-1032-00 – measured pinout
The drain and source over on the left side seem to be swapped compared to the 2N5911, although both gates are on the proper pins. This being a JFET, the source and drain may be electrically identical and it’s possible the tester labelled them backwards. The only way to be sure Tek wasn’t tragically clever is to poke around the PCB to figure out which pins connect to which other components.
So take a picture of the component neighborhood around the Q230 sockets:
PXL_20220105_210538214
Overlay it with a similar picture of the solder side, suitably reversed / recolored / transformed to match:
Tek AM503 – 151-1032-00 area – X-ray traces
The copper-side traces aren’t complete, as the red coloring marks only traces under the soldermask and omits bare solder-coated traces. Some traces on the component side run invisibly under parts. If I were doing it for money, not love, I’d pay more attention to the details.
Devote some time to tracing the traces and labeling the parts:
Tek AM503 – 151-1032-00 area – part IDs
Then doodle out the actual connections:
Tek 151-1032-00 – part connections
R246 shows Q230B lives in the left side of the can, because it’s connected between the B gate and B source pins, and confirms the tester swapped the B source and B drain pins. Whew!
R236 connects the B drain and the A source, confirming the pinout matches the 2N5911.
Comfortingly, the A side gate goes to all those other parts as it should.
So a 2N5911 will drop right into the Q230 socket with the proper pins going to the proper places. Whether it’s electrically Close Enough™ to the Tek spec, whatever it might have been, remains to be seen, but a good transistor circuit won’t depend too much on the actual transistor parameters.
Why You Shouldn’t Use Heat Pumps in the Northeast US
465
Baofeng UV-5R Squelch Settings
460
Mini-Lathe Tailstock: Alignment
449
Homebrew Magnetizer-Demagnetizer
446
Arduino Serial Optical Isolator
444
Mysterious Noise in Toyota Sienna Minivan: Fixed!
444
Baofeng UV-5: Squelch Pop Suppression
434
bCNC Probe Camera Calibration
432
Demolition Card GTA 5-10-9
431
Multimeter Range Switch Contacts: Whoops!
425
Realigning Tweezer Tips
421
Schwalbe Marathon Plus and Michelin Protek vs. Glass Chip
418
Kenmore Model 158 Speed Control: Carbon Disk Replacement
417
Kenmore Electric Dryer: Power Resistor Replacement
416
Old Kenmore Sewing Machine Foot Control Repair
414
Closing the Dmesg Audit Firehose
400
Blog Page Views
That adds up to 200 k page views from 122 k visitors, for an average of 1.6 pages / visitor, down slightly from last year. For a variety of reasons, I wrote only 242 posts over the course of the year, so more folks read only the single post matching their search terms.
To give you an idea of how awful online advertising has become, WordPress shoveled 817 k ads at those readers, slightly more than four ads per view. Given the toxicity of online advertising, I just started paying $50/year for a “personal” plan to get a few more gigabytes of media storage, which also let me turn off the ads. Most of you won’t notice, as you already run ad blockers, but it will calm the results for everybody else.
Fortunately, losing the $250 / year income from those ads won’t significantly affect my standard of living.
Subject: [redacted] review blog invitation about bluetooth programmer
Message: Hi dear,
Thanks for taking time to read this email.
I am Colleen from [redacted] brand, we sell two way radio on Amazon. I learned that you have wrote two way radio review blog before and I think your blog was written well.
Now we have a product named bluetooth programmer that need to be reviewed. […] We would like to invite you to write a review blog about it.
Your can earn $2 from each product sold! We promise it. Just put the link we provided you in your blog and the Amazon backstage will count the data. And we will pay you $2 for per product sold by your link through PayPal on the 30th of every month. (Please provide your PayPal account)
If you are willing to help us write a blog, please tell us if you have a radio and your address we will send you the product for free to review.
You can view more detailed information through this link:
Most likely, it’s just the result of an ordinary web search.
You might think everybody would know about Amazon’s crackdown on out-of-band review kickback scams, but either word hasn’t gotten around or the rewards still exceed the penalties. I think the latter applies, particularly when the offender (or its parent company) can spin up another randomly named Amazon seller with no loss of continuity.
“Earning” two bucks on a few purchases during the course of a year won’t move my Quality of Life needle, so I reported them to Amazon and that might be that.
Speaking of randomly named sellers, it’s highly likely any Brand Name you remember from the Good Old Days has been disconnected from the tool / hardware / service you remember. Perusing a snapshot of the who-owns-who tool landscape as of a few years ago may be edifying: I didn’t know Fluke and Tektronix now have the same corporate parent.
Enjoy unwrapping your presents and playing with your toys …
The Smell of Molten Projects in the Morning 