Recent Posts

Pages: [1] 2 3 4 5 6 ... 10 Next
Metrology / Re: Ultra Low Noise Reference 2DW232, 2DW233, 2DW23x
« Last post by Nuno_pt on Today at 04:55:23 AM »
We've also the express mail, that is from 100g - 250g = 4.70€ and from 250g - 500g = 6.40€ for EU.

The normal mail is 100g - 250g = 2.35€ and from from 250g - 500g = 4€ for EU.

And 0.65€ for an bubble bag, so if the 25x 2DW23x are from 100g - 250g, that will be 2.35€ + 0.65€ = 3.00€ + 23% VAT = 3.69€ if my math is correct, and I'm looking at this the correct way.

Let's see how many are need for EU & US.
Beginners / Re: Natural Response of RL/RC Circuits
« Last post by Tom45 on Today at 04:55:22 AM »
Is that decaying voltage the voltage that is calculated with V = L * di/dt?  So when current no longer flows through the inductor after the switch closes, that voltage in the inductor discharges through R3 and the switch?

The inductor discharges through R3 and R4, but otherwise yes.

So the current through the switch at t > 0 is the sum of the 1.2 A from the 30 volt supply and the decaying current from the collapsing field in the inductor.

This forum flags inductor as a spelling error. Resistor and capacitor are OK.
Beginners / Re: SMPS acting strange under heavy load
« Last post by SeanB on Today at 04:53:57 AM »
Do they look too small to be 330uF caps, and is the PCB layout where they are set up with space for larger ones? If so then they are relabelled 100uF caps, and should be replaced, along with the ones in the secondary side, as they likely are relabelled ones as well.
Test Equipment / Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Last post by tinhead on Today at 04:53:13 AM »
they actually hired someone who can at least read my buglist, and even fix some of them .. but it takes still forever ;(
Beginners / Re: Identifying unknown transformer voltages
« Last post by belzrebuth on Today at 04:52:14 AM »
Thanks for your input bktemp!
Very informative.
General Chat / Re: Perfecting my Resume [Updated] - Resume Attached
« Last post by Cerebus on Today at 04:47:40 AM »
No employer is interested in learning what hobbies you have or what musical instrument you play. If you want to nail it, consider getting help from professional resume writing service. They know the market and your local employment culture. This will be money well spent. Some of headgunting companies help their customers with this for free.

Edit: it is often easier to build you resume when applying for a particular  posted job, in which case you simply use the job description/responsibilities listed and just put the relevant information in the resume. Guaranteed, the employer will be looking for best match  to the posted job description, so this helps. Try to only answer questions the employer asked in the job post (figuratevely) and this will give you an edge over those who fills their resume with useless fluff about how good they are in areas irrelevant to the job they are applying for.

I'm guessing that you personally haven't had, as an employer, to sit and wade your way through a few hundred Resumes/CVs. I have, and most 'professionally prepared' CVs are so bad that you beg for any information that can give you a glimpse at the person behind the CV.  I can categorically state that I, as an employer, have been interested in what hobbies and pastimes an applicant has.

Also, you might think one gets a bespoke service from 'professional' resume writers. You don't. When there are 10-20 resumes prepared by the same service in a batch of 200 applications it quickly becomes clear which resumes were written by individuals and which by not just some, but which, service bureaux - the one from services bureaux tend to head for the big round filling bin faster than the others.
Beginners / Re: Identifying unknown transformer voltages
« Last post by bktemp on Today at 04:45:56 AM »
Estimating the power rating of a transformer is quite easy:
There is no hard limit, you can draw any current as long as the transformer temperature does not get too high.
So the typical power rating is the point when the temperature of the transformer increases by around 40°C without any additional cooling. I estimate the possible power dissipation based on the transformer dimensions.
You get the highest power density when the power dissipation of primary and secondary windings are equally distributed. That is how typical transformers are designed.
At 200VA the primary current is around 0.9A, so it dissipates 4.3W. The secondary current is 200VA/11.5V=17.4A, so the ideal copper resistance is 4.3W/(17.4A²)=14mohms. Since the secondary wire is quite thick and therefore needs a lot of space, I assumed a slightly higher resistance of 25mohms. But even with 15mohms the estimated power is only 230VA, so 200VA is in the right ballpark.
I'm using Bitcloud 3.2.0, which I believe has this function.
In this case you need to careful - if you enable this, then you don't have to manually go to sleep, but device will wakeup (briefly) on every hardware timer interrupt (10 ms for default system timer).

There is not much else mounted on the board except this chip and the sorroundings (antena, balun, etc, what is mentioned in this chip's sheet).
I would not expect the rest to consume more than 1mA altogether.
Have you ever seen this board to go to low power mode? Can you try to run unmodified WSNDemo and see what numbers do you get?

The problem is now, that I have 3 buttons handled by an AppTimer.
Why not pin change interrupts? Your scenario looks 1:1 like WSNDemo.

It sounds for me that polling only occurs if CS_SLEEP_PERIOD expires. CS_SLEEP_PERIOD means CS_END_DEVICE_SLEEP_PERIOD in here?
There is some mix in terminology. Internally there are 3 types of wakeups:
1. Very short (a few us) every 8 seconds - this is because of limited range of the asynchronous timer and it is unavoidable. This is totally transparent to the application.
2. MCU wakeup. When external interrupts happen. This one does not wake up the radio, but the stack (parts of it) is awake. You need to manually call ZDO_WakeupReq() or ZDO_SleepReq(), depending on hoe you want to proceed. It sounds like that's exactly what you want and it is already implemented.
3. CS_SLEEP_PERIOD - the whole stack and radio wakes up and sends the poll request.

Anyway what I'd like to do is to make HAL to differentiate it's waking up source:
It already does this. Look at WSNDemo application.
Sorry, I have no clue about that.
General Chat / Re: How many countries are cell phones made now?
« Last post by coppice on Today at 04:41:11 AM »
Cell phones are primarily made (including design) in the US, South Korea, China. Japan (Sony) is a niche player. Europe is gone: Nokia (Microsoft now), Ericsson (Sony now), Alcatel (Lenovo now), ... Motorola is Lenovo now.

Looking at those losers will teach all of us a lot of lessons. Looking at why those three countries dominate the smart phone mkt is also quite educational.
You seem to be behind the times. Cell phone manufacture is rapidly moving to Vietnam, following printer manufacture (Brother, Epson and others) which went to Vietnam a couple of years ago.
Pages: [1] 2 3 4 5 6 ... 10 Next