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General Chat / Re: Digikey's website privacy and analytics
« Last post by floobydust on Today at 01:58:00 pm »
Loaded up uBlock Origin and it stops Digikey's crap, aside from them giving out your personal account information and IP etc. to unknown parties  :rant:

Making revenue selling your customer's personal information, I think it's an awful business model, kind of hate it actually.

The Facebook scandal, the stock has fully recovered and you would have made over 28% buying in the low and dismissing privacy  :palm:
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Quote from: WacoAvionicsTech
I would like to build an add on circuit that has ovecharge protection and a charged indicator.
My favourite SLA+ battery charge / management IC is the BQ24450 (or similar). Easy to set up and does everything. Cheap and easy, with
any functions, as you need them.
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A logic analyser seems like a very useful tool for my upcoming project.

a logic analyzer (I highly recommend the dslogic knockoffs on eBay, bang for buck is untouchable)
You mean something like this: eBay auction: #https://www.ebay.de/itm/New-USB-Logic-Analyzer-DSLogic-Basic-16Ch-100MHz-4Ch-400MHz-FPGA/201435318371?hash=item2ee67b0863:g:n74AAOSwkbpa4fgl? I had looked at them before but I thought that the specs they promised where too good to be true for the price.


a used spectrum analyzer if you have some extra cash beyond the 150 to spend (I recommend either the R&S CMU200 or the HP856x series) depending on whether you are focused on repairs, digital logic work, or RF work respectively
My 9354AM apparently has all math options that were available at the time installed. Those also feature FFT based spectrum analysis. http://cdn.teledynelecroy.com/files/manuals/9300_om_reva.pdf (appendix C, page 214 onwards) Do you think that will suffice for general purpose use?


What's your soldering station situation?
I have digital 48W soldering station. Not the best but I think I could do much worse. https://www.pollin.de/p/loetstation-daytools-ls-937-450-0c-840185

Yes that is the kind of logic analyzer I was referring to. I have one, and if you get the cheap version that only has a few kb of onboard memory you can buy the 256MB memory chip on mouser or digikey for like $0.50 and solder it in yourself. You'll save money on the device and have an incredibly effective logic analyzer to boot. That's what I did anyways.

For your applications, your FFT on the scope should be fine unless you really want to get into the weeds analyzing signals with frequencies greater than 1GHz, then you'll need something like the R&S CMU200

That soldering station will probably be ok; I prefer Weller or Hakko for proven reliability and quality.

Good luck with your project!
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Yeah, and what happened to the op?, ran out of flux?
In particular, why "Banned!" ? I missed the reason for that one...

Don't recall exactly, but pretty sure it involved sockpuppetry.
Just banned someone the other days who had no less than 4 anonymous active accounts, and he's not a happy camper.
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Consider the situation in Figure 1. Each period produces a result - either G or L. These results are analyzed over the averaging interval. If the probabilithy of obtaining G is p, then the probability of obtaining a L is 1-p. For simplicity it is assumed that p=1-p=.5.

For measuring oscillator stability the statistic of interest is not how many Gs or Ls appear in an averaging interval, but the difference between these values. The process represented by an averaging interval is well-known and is called a bernoulli trial. The expected value of the difference between the number of Gs and Ls is presented here, specifically: 2mp - m = m(2p-1) = 0. [Note: the referenced web page uses n as the number of trials, whereas here that value is m. The value n is used here to represent the number of averaging intervals. Also, the problem solved there is stated in terms of successes and failures. The logic is exactly the same. Simply substitute L for success and G for failure.]

The variance of the difference between the two random variables in a Bernoulli trial (see above reference) is: 4mp2 = m. Notice (!) that the variance depends on m. So, as the value of tau increases, so does the variance.

Your picture of an oscillator has evolved from a Gaussian distribution (in earlier posts) to a binomial distribution, but the distribution for any real oscillator is not purely one or the other.  Oscillator noise is complicated -- it cannot (generally) be reduced to a simple Gaussian process with it's "jitter" described by a single parameter, i.e. by a standard deviation.

Quote
Given the capabilities of computers in the 1960s and 1970s, when Allan Variance was developed, it was necessary to increase tau in order to obtain long-term measures of clock stability. Today, computers are much more powerful. So, it would be interesting to determine the sample_time/tau ratio above which an analyst would be forced to increase tau in order to obtain practical clock evaluation results. This would, of course, depend on the computer available. However, I would guess most desktop systems these days could analyze a very long data set in a practical amount of time.

Allan Variance calculations are very simple calculations.  They do not require much computational power, even when measuring long term stability. Tau is often increased for long term measurements because there are hardware advantages (reduced dead time, higher counter resolution, etc.) and it is computationally convenient to simply increase tau instead of increasing the number of data points. There are no serious disadvantages to increasing tau instead of increasing the number of data points.

An example: Let's say you want to measure the Allan Variance from tau = 1 s to tau = 105 s. To get a reliable Allan Variance at 105 s, you will need 106 s of data.

Method 1) Collect 106 counter readings with a gate time of 1 s. Total number of data points is 106, and the total acquisition time is about 278 hours.

Method 2) Collect 103 counter readings with a gate time of 1 s, then collect 104 counter readings with a gate time of 100 s. The total number of data points is about 100x less than method 1, the dead time is about 100x less than method 1, counter resolution is improved, but the total acquisition time is only about 17 minutes longer. Resulting Allan Variance will be consistent with that attained by method 1.
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Beginners / Re: Bypass thermistor safety circuit
« Last post by raybies on Today at 01:50:10 pm »
All I'm doing is replacing the battery pack. I have no idea what's in the original pack, bcos I don't have an original pack.
My assumption is that the pack provides 58v and that's what I am supplying, but I have tried 48-58.8v.
Everything works fine for 5 seconds.
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The video output is actually supposed to be color. It's not proper color but rather a rainbow that gets overlaid on top of the white elements to give the illusion of color. The effect of which can be seen here. The overlay actually comes through perfectly if I remove R10:



Could it be that perhaps L1 and L2 are necessary as some kind of filter?
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EEVblog Specific / Re: 4K Video Editing PC Build
« Last post by EEVblog on Today at 01:41:49 pm »
I'm well aware. I can see a large portion of them you know. But you only seem to reply to comments which push your buttons.

It only seems that way, but that's not true.
I'll let you in on another Youtuber secret and why a Youtuber might respond to question or comment in what might seem like a harsh way;
When you ask a question, you are often not aware that a dozen or a hundred other people might have asked the same question, or made the same comment. So it's often not the first time the Youtuber has seen that question or comment, it could be the 10th time, or even the 100th time. That can be kinda frustrating sometimes.
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Microcontrollers & FPGAs / Re: multiplexing five analog signals
« Last post by Geoff_S on Today at 01:40:21 pm »
Would something like the Analog ADGS5414 work for you ? 
http://www.analog.com/media/en/technical-documentation/data-sheets/ADGS5414.pdf
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EEVblog Specific / Re: 4K Video Editing PC Build
« Last post by EEVblog on Today at 01:39:52 pm »
So you just pulled the most expensive i7 you could see out of a hat and went with it.

Not quite.
It was faster than the 8700K, not nearly as expensive as the i9's and others, it was on special at my local store, and by all accounts I could find is a pretty decent CPU and had good benchmark results.

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