Recent Posts

1

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

« Last post by m k on Today at 11:19:29 am »

Around here original flu shot gave some narcolepsy symptoms, mostly permanent I guess.
Then the vast majority of vocal minority were crying major error in vaccine.
Adjuvant was the supposed cause back then, also a must for enough shots in time, of unknown H1N1 spreading.
Spanish flu was the obvious scare, and dropping out from the vaccine queue.

Same time China was giving that same vaccine and quite a bit more than here.
Final outcome, that had only very little news coverage, was that vaccine wasn't the thing, it was genetical.
So the live virus, that was not present in vaccine, was the reason, combined with a genetical exposure.
Good thing was that all compensations were left in place, without any hassle.

One other thing, live viruses and their doings.
My guess is that many don't understand what it means for everyday life and exposure.
Especially when very viral bug is in question, like norovirus.

One thought for young vs. old.
If virus goes to lungs it's, up to the point, good the have worse than better immunity.
Very good immunity can hit back so hard the you'll finally suffocate.

Then there is this society vs. individual.
Maybe a poll of how high hit rate one would still try to miss.
I've heard that some have tried 1/6.

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Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by john23 on Today at 11:18:48 am »

Hello XVR,siss65dn sounds great,however I need to use CGHV1A250F amplifier.
regarding being able to hanle rise and fall times.
As you can see in te attached photo they put very very large capacitors.
suppose for the drain i will only put  1uF + 470pF.
I=CdV/dt
C=470pf
dV=45V
dt=100nsec
so 1470pF*45V/10ns=6.6A which is possible with this great mosfet.

The problem with this new  CGHV1A250F amplifier the it needs 45V on the Vds to function.
However siss65dn  PMOS has tottaly different  .
Where in the datasheet i can see the needed Vds for 6.6A .

even if we needed 12A for example from this mosfet :-) how can connect this mosfet with the new amplifier so each one of them will get the bias it needs for proper functionality?


Thanks.


https://www.alldatasheet.com/datasheet-pdf/pdf/1673867/WOLFSPEED/CGHV1A250F.html
https://www.mouser.co.il/ProductDetail/Vishay-Semiconductors/SISS65DN-T1-GE3?qs=gTYE2QTfZfRTVNwOG%2FwJeQ%3D%3D&_gl=1*1ew6q0n*_ga*MTc3OTc5NzEwMS4xNzE0MzE3MTU5*_ga_15W4STQT4T*MTcxNDgxNzUzNi41LjAuMTcxNDgxNzU0MS41NS4wLjA.

3

Projects, Designs, and Technical Stuff / Re: Emergency stop for runaway large DC motor

« Last post by Muttley Snickers on Today at 11:16:59 am »

Just fit a normal manual E-Stop in reach of the operator, which cuts supply power seperately to the motor driver

You REALLY should have one of these anyway, because getting your head dragged into a lathe and being unable to stop it, really isn't very nice (don't, unless you really are not squeemish, google this, because the pictures are pretty horrible.........)

I'm going to assusme you are not silly enough to leave the lathe spinning un-attended btw!

That's exactly what I did by installing an additional E-Stop switch at knee height when we were first setting up my lathe after the unboxing. I wasn't happy with the location of the factory fitted combination Start/ Direction/ E-Stop panel which looked like a tacked on afterthought mounted on top of the gearbox.

I recognised immediately that if I got caught up there was no way to stop the machine, and as a machining nut I have also seen those disturbing images. Fortunately there was a screw on cover over a cavity cast in the machine alongside the gear selection levers which is where it appeared they intended to put the control panel, so it was an easy install and I already had the kill switch in stock.

The lathe is a Hafco AL320G, not a huge machine but heavy and plenty of grunt with both 160mm 3 jaw and 200mm 4 jaw chucks, and every edge on the machine and its accessories are like a razor blades. I can post a picture tomorrow for reference but a warning, machining involves plenty of blood, sweat and tears so one needs to regularly check that the stuff dripping on the floor is just oil and cutting fluid.

4

Microcontrollers / Re: SD Card reliability in SPI mode

« Last post by coppice on Today at 11:15:16 am »

The cards are fine. They're reading on a PC. You need to step through the initialization and file listing process and find where and why it's failing.

The fact that a card reads on a certain machine does not mean its fine. If there are cells approaching the marginal condition as they wear out, they may read and write OK on one machine and give errors on another with slightly different voltages, or decoupling quality. I don't think SD cards have an ability to scan for marginal flash cells in the way, say, some MCUs can do these days. So, you can't really do a performance analysis on a card, except, perhaps, by cooking the supply rail, and seeing how sensitive to operating conditions it is.

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General Technical Chat / Re: What ICs are used in this rocket?

« Last post by soldar on Today at 11:15:12 am »

It's all noodle logic.

6

Beginners / Re: how can I measure AC voltage of bridge diode on PCB of CRT TV?

« Last post by MathWizard on Today at 11:14:03 am »

I don't like probing by hand much of anything AC powered, especially if I don't know the circuits. Do you have alligator clips, or a soldering iron ? With the power off I'd find solid places to attach clips, or solder on wires, and clip onto them.

If you're not sure about using a DMM, I'd say read up on some safety stuff too. Modern TV's can still have some pretty high voltages in them, even after turned off for a while.

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Power/Renewable Energy/EV's / Re: Flyback controller output voltage and amps under load

« Last post by Faringdon on Today at 11:12:11 am »

And you are measuring vout right at the output capacitors of the SMPS?

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Test Equipment / Re: Who is the OEM for this PSU? Multicomp MP711057

« Last post by csuhi17 on Today at 11:07:15 am »

https://www.aliexpress.com/item/1005004866118328.html?spm=a2g0o.productlist.main.9.2774FRDAFRDAXJ&algo_pvid=e26830f6-9ce4-46f2-8c52-81d6dc728aa7&aem_p4p_detail=2024050404052713560946799941560001871184&algo_exp_id=e26830f6-9ce4-46f2-8c52-81d6dc728aa7-4&pdp_npi=4%40dis%21USD%21241.30%21108.58%21%21%21241.30%21108.58%21%402101fb0a17148207279417611ee966%2112000038633526296%21sea%21HU%210%21AB&curPageLogUid=CCIMXa7n4cCu&utparam-url=scene%3Asearch%7Cquery_from%3A&search_p4p_id=2024050404052713560946799941560001871184_1

https://www.aliexpress.com/w/wholesale-owon-spe6103.html?spm=a2g0o.home.auto_suggest.2.650c76dbZId3q5

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

« Last post by coppice on Today at 11:04:57 am »

Do you realise that if you keep taking a vaccine you loose immunity to the disease it is for? This is one of the body's regulatory mechanisms, which limits auto-immune diseases from wiping us out.

Coppice, come on! I expected better from you. This isn't the case at all.

So, you think more and more is better and better? That's unlikely to be true. Everything in a biological system is about balance. Not to little of something and not too much. Why would you expect the immune system to be any different? Try reading on the topic, and you'll find exposure to pathogens, whether natural or mutated ones in vaccines, is the same kind of balancing act as most other things you may put in your body. There are reasons why vaccines have a dosage program, and its more than just too much is wasteful. Try reading on the topic. COVID got me interested in the immune system, so I read. There is plenty of easily accessible material out there. The interplay of the immune response to infections, and how well the body cleans up its own mutations, and avoids them developing into tumours is really interesting. The thymus is a pretty interesting organ, that's only really active in early childhood, and whose purpose is to help train the body's immune system to distinguish self from non-self. Without that functioning a baby descends into an auto-immune death spiral. The thymus is a fascinating natural solution to bootstrapping a functional system.

Most of what people colloquially refer to as vaccine booster programs aren't. A lot of people say they take a flu shot each year, like its the same shot over and over. It isn't. Its a new cocktail every year, based on the flu variants that seem to be around.

10

Beginners / Re: Lab PSU for learners

« Last post by MathWizard on Today at 11:02:52 am »

Yeah Agilent is a top brand, it's a fairly new PSU if it's only from the early 2000's. Overall that would make it harder to repair, compared to ones made with all discrete parts, like something from the 1960's. But there's still lots that could be repaired on them.