Recent Posts

1

Repair / Re: Desoldering advice

« Last post by tooki on Today at 03:07:51 pm »

It tested fine, all components under it tested good too.  I used some 63-37 and wicked it off to remove the low MP alloy, then put the relay back in with some Sn Cu Ag stuff that melts at 237°C instead of using the 60-40 188°C stuff I usually use.

I assume your SnAgCu is actually 227C.

Anyhow, in the future, I’d avoid mixing up all these alloys — or at least “rinse” with your final solder multiple times. In particular, what you really want to avoid is soldering with tin-bismuth after using tin-lead: lead lowers the melting point substantially, and can result in an alloy that melts below 100C!

2

General Technical Chat / Re: H5N1 bird flu and how we're risking another global pandemic

« Last post by CatalinaWOW on Today at 03:04:58 pm »

Sustainable farming will only support a sustainable human population.  Which may take a pandemic to achieve.

3

Microcontrollers / Re: SD Card reliability in SPI mode

« Last post by coppice on Today at 03:03:40 pm »

Fairly sure any recent major brand microSD cards would have wear leveling implemented: https://forums.sandisk.com/t/which-sandisk-cards-support-wear-leveling/34679/4
But good idea to use something like littlefs, unless OP wants to implement a battery or supercap to guarantee safe shutdown.

I wouldn't trust that to be true. Even if the data sheet says there is wear levelling it might be some crude implementation that doesn't help much. SD cards have a horrible history of wearing out when used for heavily reused areas, like swap space, where they may only last days. I was still seeing that happen 5 or 6 years ago. Many SD cards also fail completely  after weeks or months, without particularly high usage. There is some evidence that this may be associated with particular products they are plugged into. For example, one of the Samsung Galaxys, I can't remember which, had a huge problem with dying SD cards. That doesn't seem to be your problem, though, as you indicated the cards become flaky rather than die completely. If they are wearing out, and write more reliably on one machine than on another, look at the power supply. Any setup with a droopy supply is likely to show up worn areas first. A rock steady supply will ensure they get pumped to the maximum.

4

Test Equipment / Re: Enabling options on Agilent ESA series E4402B E4404B E4405B E4407B

« Last post by Larry_Bridge on Today at 03:01:02 pm »

Hi friend,

I have E4404B with serial number MY41441147 and HostID: B842CBEA.
can you generate license code for options: 1DR, 219, 226 ?
Thank you.

5

Beginners / Re: Any off-the-shelf clock using DS3231?

« Last post by Peabody on Today at 03:00:43 pm »

I think even more accurate would be a clock that receives the time signals from WWVB in Colorado.  They are called "self-setting", or sometimes "atomic" clocks.  They need to be able to receive the very low frequency WWVB signal, but that frequency goes through walls pretty well.  In theory you never have to set them, and will never be more than one second off if you have good reception.  But even if you get a good signal only at night, it's never going to be off enough for you to notice.  Look at the WWVB entry on Wikipedia.

I suspect most normal clocks just use a crystal, which is a lot cheaper than a DS3231.

6

General Technical Chat / Re: piano switch

« Last post by vivi-d on Today at 03:00:03 pm »

Thanks for the great explanation

I'll watch for clues like that in the future.

7

Projects, Designs, and Technical Stuff / Re: Opamps - Die pictures

« Last post by Noopy on Today at 02:58:32 pm »

 

That´s ok for me.
The "four terminal problem" is another reason why I don´t like drawing MOS schematics... 

8

Projects, Designs, and Technical Stuff / Re: PCB humidity measurement circuit design

« Last post by GigaJoe on Today at 02:58:24 pm »

I would consider it as a joke ,
for a very simple reason ...  any analog humidity sensors have a special compound that change resistance absorbing water molecules.

from your question I would assume that epoxy foundation of PCB significantly change resistance , ( or capacitance ,  or some other  electrical parameters ...)
And that would be real fun ....  to see electronics behavior in real life ...  after rain outside ... for example ...

...   take a real sensor intead ..
https://www.newark.com/multicomp-pro/mp007422/humidity-sensor-w-o-case-90rh/dp/45AJ6216

9

Buy/Sell/Wanted / Re: WTB (UK/EU)- Toroidal coil winder & bobbin coil winder

« Last post by coromonadalix on Today at 02:57:06 pm »

For professional use ?

You surely know about diy ones ?

10

General Technical Chat / Re: Cable Management

« Last post by reboots on Today at 02:56:58 pm »

Most of my test equipment is in a 2-post aluminum telco rack. I have a couple of the Pomona cable racks mounted sideways, 90 degrees from the design orientation, on one of the posts. They work almost as well vertically as they do horizontally, and the cables take up less space. Not quite as convenient for avoiding tangles.