Recent Posts

Pages: [1] 2 3 4 5 6 ... 10 Next
1
Thermal Imaging / Re: seek thermal xr- otg connection plug broken
« Last post by Fraser on Today at 12:46:41 am »
Farnell (Newark in the USA) sell several types of male Micro USB plugs at less than. £1 each.

http://uk.farnell.com/w/c/connectors/usb-connectors-adapters/prl/results?st=Micro+USB+plug

The plugs are the same whether for OTG or non OTG use..... 5 pin.

There may be similar chassis mount plugs on eBay but finding them amongst all the other micro USB stuff can be a challenge :) Plus quality varies.

Fraser
2
Yep, you keep digging that hole "Fungus"  :-DD

What hole?

In practice brick wall filters cannot be achieved in hardware, they have to be done in software.

This means that if you want a 'scope with a a non-gaussian filter you have to sample at a much higher rate than Nyquist then digitally post-process it.

ie. you have to massively underrate the bandwidth which is printed on the front - inside the oscilloscope it has to actually have the bandwidth needed to match the sample rate.

In other words, it's a bit of a con game played in "high-end" oscilloscopes. That Tek paper which was posted earlier is really just a sales brochure in disguise ("You want a 'scope with only 3% error in rise time instead of 30%? We sell those!").

The reality is that a 'scope with 3% error is just a scope with 30% error (ie. gaussian filter) that's been derated, has a software filter applied internally, and a different label stuck on the front.

If you want to believe those scopes are breaking math, well... that's up to you.
3
Beginners / Re: Diodes in parallel.
« Last post by Hero999 on Today at 12:43:41 am »
In the prototype I worked on, lots of 1N5822 diodes were connected in parallel, which worked out much cheaper, than a more beefy diode and the package was more convenient for a quick lash-up, than an SMT package.
Did you dare to use thermal imager?
No, there was no need to because none of the devices came anywhere near to overheating. Using multiple, smaller devices also spread the heat, over a larger area, which removed the need for a heat-sink. The voltage drop was significantly lower, with all the devices in parallel, than the equivalent big rectifier and was sufficient for the application, which only needed 10A continuously, 15A peak and 8×3A diodes gave ample headroom.

It simply isn't true that one diode hogs all of the current. It's true that current sharing is not perfect, but it's not all or nothing, like you're implying. This isn't the same as connecting multiple discharge tubes in parallel, which would indeed result in one device firing, leaving the others unused.
4
Test Equipment / Re: Handheld meter electrical robustness testing.
« Last post by rsjsouza on Today at 12:43:37 am »
Joe, I don't know what control unit you had or how many stations, but I recently replaced an ancient Toro unit with this one from Orbit. The advantage is that it is enclosed, which even in a garage it will probably have a long life (my older unit was eaten from rust coming from dust and spider webs).

Your ancient Toro controller was much newer than mine.  :-DD  Mine uses a mechanical timer with programming pins.  Why they even put a microcontroller in there, I am not sure. 

I started to look at new ones but they all take a battery for the RTC.  I don't need it to call my cell phone that I don't have have, update my blog or graph my water usage.  It's grass, it gets water, don't over complicate it.   :-DD
That was a concern of mine as well; both units (the old and the new) only use it for the RTC and to keep the programming in a power failure. I explicitly avoided the Wi-fi connected units because of that.
5
General Chat / Re: Why SpaceX Are Going to Beat NASA to Mars
« Last post by EEVblog on Today at 12:41:06 am »
Bullshit. It's been possible for decades. It always dies on the vine.

That doesn't mean larger space tourism won't be viable in the near future, there have been a LOT of advances since then in cost reduction and specific private venture companies dedicated to it. Space tourism has already happened.

Quote
"If going to the moon was safe enough and relatively cheap enough,"
Yeah and if my grandma had wings she'd be an F-15. So what? It's all just bullshit dreams, Dave.

Except for the people who have already paid $20M a pop to go into space, it's already an industry that has had a half billion dollar customer turnover. Not to mention those who have already ponied up the money to go with Virgin Galactic.
Bullshit dreams huh?

Quote
Going up in MiG-29 is not just "practically" doable, it is LITERALLY doable. How many do it? Did you?

Thanks for bringing that up. I was actually very close to paying the $10,000 or so back in the 90's when this became a thing. I was seriously trying to decide between a Mig-29 and SU-27. I'm not joking, I almost booked the ticket. Ultimately decided it was better to save that money at the time due to various circumstances. Sure I talked about this in a live show long ago.
It's still on my bucket list.

Quote
Why not? Because you are more attracted to the dream than the reality. If everyone COULD go to the Moon, you'd want something even more exotic because this isn't about space, it's about a dream. You'd want to visit the core of Jupiter instead because THAT's unattainable.

You don't seem to be grounded in reality.
Of course not everyone goes on these thing, majority of the population of the US for example have never even left their own country.
I would not go for a shot into space or the moon right now because I have kids I want to see grow up, and the circa 1% chance I wouldn't come back is too high for me. But in my retirement I most certainly would take that risk.


Quote
That's fine, just don't confuse daydreams with the toxic space religiosity or sci-fi nonsense of children who grew up on TV and no critical thinking skills.

I'm basing this on actual data, and the blindingly obvious psychology of human adventure.
Do you think those 1000+ people a year who pay $50k+ to be hauled up everest for bragging rights and spend a few months doing it in horrible conditions would rather do that, or take the same chance of death and fly to the moon instead that could be done in a week in far more comfort and also zero prep in comparison? FYI, there is already a zero death rate for space tourism, and it's an actual thing.
And that's just for starters. Once people see it's a "tourist thing", albeit an extreme once-in-a-lifetime tourist thing, they will flock.
Heck, once-in-a-lifetime trips to the antarctic take longer than a moon flight would.
6
Is it possible to change the mounting point at all to just keep the lens from being the point of contact?  Or is it possible to use some other material to build up areas near it to at least share the pressure?

I guess my first instinct would be to try to lessen the blow on the sensitive parts rather than just trying to strengthen the part itself, at least in the case of something that's already small and fairly durable on something so large.
7
I thought wifi is only in 5.725 to 5.875 GHz ISM band,I googled it and yout right! Is the 2.4 GHz wifi wider too than the 2.4 to 2.5 ISM band?
No. (Surely the same page that confirmed what I said would have answered your question?!?)

https://en.wikipedia.org/wiki/List_of_WLAN_channels
8
- Any thoughts/ideas/recommendations?

Check out the Tektronix AM502 which can provide a gain of 100,000 (100db) with a 1 MHz bandwidth.  It was made for exactly this type of application.

Quote
- If I have to design something from scratch, do you think a single low-noise op-amp stage (or instrumentation amp) with 60dB gain at >20KHz be feasible?

Not without a lot of care in design and construction.

Quote
- Also am I right to look for op-amps which perform well with high source impedance of approx. 10MOhm to support a 10x probe and/or high impedances for probing with a 1x probe?

There are some suitable JFET input operational amplifiers but watch out for variation of input bias current and input capacitance with signal level.  Low frequency noise will be a limitation and MOSFETs are worse in this regard.  High open loop bandwidth in the first stage to get high gain will be counterproductive because high bandwidth devices are also higher noise.

Quote
- Or alternatively would you recommend to look at discrete jfet designs?

Check out the Tektronix AM502 for an example of a discrete JFET design.  Notice that neutralization was used and gain of the JFET stage is relatively low.

A discrete JFET input design could have 1/4 the noise of an equivalent integrated JFET design but other considerations are more important.

Quote
Such as Fig. 4 from http://www.janascard.cz/PDF/Design%20of%20ultra%20low%20noise%20amplifiers.pdf

That is AC only.

I suspect you are going to want a differential input like the AM502 to avoid noise contributed by ground loops.
9
You didn't answer how electric cars for a tiny minority address progress for HUMANITY (7.5 BILLION) when a lot of people don't even have sewage systems?

I'm not the one talking for the whole species here.
Than why are you not fixing that to your ability if you have such high morals?

Shifting goalposts. YOU are the ones with the "high morals" of speaking for Humanity while beating your meat to rocket pictures. How does THAT help poor Africans? It doesn't, it just makes YOU feel good while YOU do nothing.

You don't know what I do or contribute to, because unlike you lot of space-on-the-brain puerile dreamers, I *DO*, I don't *talk*.

I used to be a Space Nutter just like you guys. When I was young. Part of growing up is realizing that limits exist and fairy tales are just fairy tales.

I recognize word for word the same exact drivel and Future Of Humanity(tm) and Space Catastrophe(c) nonsense I spewed decades ago. The painful truth of it is that it's a religion.

https://www.theatlantic.com/technology/archive/2012/03/the-holy-cosmos-the-new-religion-of-space-exploration/255136/

https://en.wikipedia.org/wiki/Russian_cosmism

It's all nonsense. It hurts to grow up but that's reality. It's just you and me right here on this planet. You will die here, your children will die here, their children will die. No one is going anywhere. Not now, not ever.

It's done. Deal with it.
10

During development you can you *everything* through SWD  (it will get you up an running much quicker).   This includes programming external flash.

The Manufacturing Tool (and the flash loader tool) are more for factory programming once you are in production.   

Do you mean that I can program the QSPI directly by SWD without using OpenSDA? I have read that to program QSPI or SD card, directly, without using OpenSDA, I must connect via USB or UART to a PC and use the MFG software.

SWD I understood, that it will only work for Debug, not to directly program the QSPI or the SD card.


Quote
I have not used a configuration where you boot from SD and then program the QSPI.       You may need to write your own 2nd stage bootloader if you want to be able to select which images you want programmed.   I.E.     Boot via SD (load program into internal RAM) and then that program looks for files on the SD card to program the QSPI.      You would also probably need some configurable pin strapping to boot from SD when there is a card present vs boot from QSPI when running application software.

I generally always write my own  2nd stage bootloader to have some additional flexibility/control of the process.

You use case probably is supported, I just have never done it.


The question is how to provide firmware updates to the end user, so that they can be uploaded from the SD card to the QSPI. All my boards with Kinetis MK66 install a micro SD card to update the firmware, and I want to do the same with the RT1020 board.

All the examples in Application Notes for loading firmware in RT1020 and RT1050, without using OpenSDA, are made by connecting the board, by USB or UART, to a PC computer, there are no examples to update the firmware of QSPI with SD card.

To provide firmware updates, if the board boots from the SD card, I understand that I simply need to provide a copy of the SD card programmed for the first time with the MFG tool, although there is also no information in the Application Notes about it, I'll check it for myself.
Pages: [1] 2 3 4 5 6 ... 10 Next