I needed some cheap little vregs recently and had run out of and/or lost all of my useful-value 780x linear parts, so I decided to look at what people in this century use.
I found some little buck boards roughly the size of a TO-220 package that looked exciting. These particular ones are QSKJ Mini DC-DC Buck Step Down Module model “QS-1205CME-3A”, Vendor page here, mine were 5pcs/$9 from Amazon.
Upon analysis they have serious issues with regulating under load, so the hunt for something decent continues, but the form-factor and advertised feature set are really compelling.
High-efficiency high-frequency synchronous buck instead of a linear heater^H^H regulator.
Solder-jumpers for 1.8,2.5,3.3,5,9,12V or a default (fiddly, tiny) adjustment pot output so you only have to stock one device – one easy-to-cut trace to disable adjustable mode.
Tolerates 4.5-24V input as long as out < in or so.
Good stability to input voltage variation.
Does appear to have a cutoff for over-current.
No perceptible ripple under various load conditions.
Voltage regulation manages maybe 600mA at 5V before droop becomes unacceptable (<4.8v).
…and that makes it basically useless for most applications. Test data below the fold.
Maybe it could be resolved with appropriate external capacitors and/or offsetting the adjustable to regulate right at a known load or something, but not being drop-in really reduces their charm.
Anyone know of a similar offering that doesn’t suck at output regulation? (Rel: Anyone know if any of the low-end electronic loads are worthwhile? I’m not looking to spend real-lab-instrument money, but it’s come up often enough lately that I want to be able to dissipate a couple 10s of Watts through a at least stepwise-controllable resistive load).
I ran into a delightful irony trying to help a student get set up for the embedded systems lab I’m running this semester: Neither Keil MDK ARM (a first-class ARM development environment) nor the Stellaris ICDI Drivers (TI’s programming/debug interface for their smaller ARM processors) will run on Windows 10 ARM. I think this is also the first time I’ve seen a Windows 10 ARM device in the wild.
(For those who know ARM stuff, yes, Keil is kind of crusty, but we like the textbook we’ve been using, it uses Keil style directives and TI details, so switching to CCS with TI parts or a different ARM family would require major retooling.)
I let WordPress update itself and am hitting a bug with image aspect ratio, it appears to be a known regression that was pushed in a release, even though I’m running an unmodified theme from upstream. I don’t have the time or the fu…energy to deal with it right now, but will hand-patch the theme if it isn’t patched upstream in a few days.
I’ve been idly looking for one of the mid-90s ThinkPads known to have perfect OpenStep/Rhapsody support for years as a fun collector piece, but been unwilling to pay eBay prices. The other week I scored a pristine IBM ThinkPad 560E for $20 in a Shopgoodwill auction, below is notes on getting it up and running, plus some relevant history and plans.
This post is a retro post on a retro topic – a repair I did in 2017 on a monitor made in 1991. I got a question about (probably) the same problem in another venue and realized I never put it online. I managed to dig up my pictures and notes, so there is useful information to be shared.
The end of my (2016) post about Recapping my Macintosh LC I discovered that my matching Apple 12″ Macintosh RGB Monitor ( M1296 ) was going pear-shaped, and speculated that I’d need to recap it.
I have a machine with SSH exposed on one high-numbered nonstandard port forwarded through a NAT. A few days ago I noticed some log noise about failed SSH logins and turned on fail2ban with sane defaults. It banned almost 300 addresses the next day. Looks like a botnet of compromised VMs, most of the random sample I whois‘d are from cloud/telecom provider’s IP ranges. The only common-ish use of the port in question is a very obsolete game matching service, and a couple machines behind the NAT with SSH on consecutive ports aren’t being harassed.
I’m used to attracting unwanted attention running services on standard ports (another machine that runs SSH on port 22 + HTTPS on 443 usually hands out at least 2000 bans a day), but this is new. Is the Internet that hostile now that bots are roving around in the 4-digit ports startin’ shit? Are there new behaviors that attract unwanted attention?
I had my dear old Macintosh SE out for a health check as I slowly extract my vintage computer collection from the (unconditioned) place I’ve been keeping it at my parents house to the basement of the place I’m renting. It had a couple interesting findings that seem worth putting online, including another floppy drive rebuild and a slightly elaborate fan replacement.
Why did a Banggood package I ordered on March 26 just appear in Bahrain on July 5, the same day it finally showed “Shipment picked up?” Did it just get packed into a container and loaded on whatever outgoing vessel they could throw it on to get it out of their warehouse, and it was finally reprocessed there? Is it taking a tour of human-rights-violating trade partners for sport?
I’ve had China-export stuff with possible customs issues get routed through the Netherlands before, but the other package from the same order had lock picks and came faster and more direct.
ED: Since it arrived, full path for maximum hilarity:
Jul 07, 2020 10:33 Delivered
Jul 07, 2020 08:37 With delivery courier
Jul 07, 2020 07:34 Arrived at Delivery Facility in ERLANGER - USA
Jul 07, 2020 06:59 Departed Facility in CINCINNATI HUB - USA
Jul 07, 2020 00:48 Clearance processing complete at CINCINNATI HUB - USA
Jul 07, 2020 00:46 Processed at CINCINNATI HUB - USA
Jul 07, 2020 00:38 Arrived at Sort Facility CINCINNATI HUB - USA
Jul 06, 2020 21:02 Departed Facility in EAST MIDLANDS - UK
Jul 06, 2020 20:59 Transferred through EAST MIDLANDS - UK
Jul 06, 2020 18:59 Departed Facility in LEIPZIG - GERMANY
Jul 06, 2020 18:57 Transferred through LEIPZIG - GERMANY
Jul 06, 2020 18:08 Customs status updated
Jul 06, 2020 07:14 Departed Facility in BAHRAIN - BAHRAIN
Jul 06, 2020 05:05 Processed at BAHRAIN - BAHRAIN
Jul 05, 2020 17:18 Arrived at Sort Facility BAHRAIN - BAHRAIN
Jul 05, 2020 16:07 Departed Facility in BAHRAIN - BAHRAIN
Jul 05, 2020 14:05 Processed at BAHRAIN - BAHRAIN
Jul 05, 2020 13:37 Shipment picked up
Jun 20, 2020 09:15 Package has been sterilized and shipped out.
Jun 19, 2020 08:45 Our warehouse has started packing your items.
Mar 26, 2020 00:14 Order submit.
I’ve seen a spate of articles pop up recently discouraging people from going to college in fall 2020 because of the COVID-19 pandemic situation. They’re mostly from self-mythologizing startup douches and/or carpetbaggers trying to sell alternative education products, so there isn’t much of value in them and I won’t be linking.
However, talking about them has me refining and recording the advice I give to prospective college students. So in that interest, a list of my usual advice. Which is very, very explicitly prefaced with the usual “Opinions expressed are solely my own and do not express the views or opinions of my employer” disclaimer.
During the first week and change of our vast national COVID-19 induced remote teaching experiment I made some notes on practices and improvised some equipment that has proved useful, and seems worth sharing with others.
This two week period I’ve primarily been running lab sessions to help my herd of mostly-Sophomores do and get sign off for a digital design lab exercise using Verilog to implement state machines, adapted slightly from our usual lab at this time in the semester.