Recent Posts

1

Test Equipment / Re: DG4000 - a firmware investigation

« Last post by RoGeorge on Today at 10:59:17 am »

By the high Z question, this is probably your first AWG generators.  Most probably the generator is calibrated and working fine.  The amplitude is constant only when the cable is also 50 ohms, and properly terminated in 50 ohms, otherwise the output can be very different than expected.

You may want to read about terminators, reflections, transmission lines and standing waves.

2

Projects, Designs, and Technical Stuff / Re: Does anyone here use docbook?

« Last post by voltsandjolts on Today at 10:55:51 am »

I circle this problem myself every now and again, but always seem to fall back on the lowest-common-denominator we use at work: MS Word. I give up on getting an engineering team to agree on anything else.

Given the choice, for technical documentation I would probably be looking at choosing between:

AsciiDoc
asciidoctor - see the RP2040 datasheet as an example. This can generate docbook so might interest you more.
https://github.com/bodiam/awesome-asciidoc

reStructuredText
restructuredtext - used for python documentation
https://github.com/ralsina/rst-cheatsheet/tree/master
https://github.com/vscode-restructuredtext/vscode-restructuredtext

3

Cooking / Re: [US] I require chicken salt

« Last post by jpanhalt on Today at 10:52:37 am »

@tooki

We both enjoy chemistry; although, it seems neither of us did/does that strictly for a living.  I may have mentioned a book I refer to often on food chemistry:  "Food Chemistry, 3rd Ed." H.-D. Belitz, W. Grosch, and P. Schieberle, Springer, Germany, 2004.*  That's the English version.  I am sure there are other books.  The sections I refer to mostly are the spices. 

*https://www.amazon.com/Food-Chemistry-H-D-Belitz/dp/3540408185

4

Repair / Re: strange low frequency switching noice from diy sg3525 smps

« Last post by T3sl4co1l on Today at 10:51:09 am »

Compensation problem, then?

Again, completely in the dark without an oscilloscope -- you're seriously handicapped without one, we can only guess.

Tim

5

Test Equipment / Re: DG4000 - a firmware investigation

« Last post by Blanc on Today at 10:49:40 am »

Thank you for your reply.
Reading your explanation, it seems like the DG4000's discontinuity is coming from the bug of calculation software and/or incorrect calibration. A kind person gave me an archive of old FWs containing the bug fix history. Although the history was not detailed, it seems likely that updating the FW and performing appropriate calibration will resolve the issue.

Unfortunately, I don't have a USB memory that the update process of DG4000 can recognize, so I haven't updated the FW yet.

Thank you again giving  me a manual for the calibration.
Fortunately, I already have a six and a half digit DMM, but no high frequency power meter.
However, I don't think the accuracy of high frequency output is much of a problem.

It's good for me that my troubles are not due to hardware.
I have already opened the cabinet and checked the PCB.
Seeing the small surface-mounted resistors and relays seemed a bit cumbersome.

6

Cooking / Re: [US] I require chicken salt

« Last post by wraper on Today at 10:41:56 am »

Isn't it something like bouillon cubes, just in loose form? https://www.walmart.com/ip/Knorr-Chicken-Bouillon-Cubes-9-3-oz-24-Pack/10291771

7

Repair / Re: 18V/3A HY1503 PSU - weird CC/CV behavior while charging battery cells

« Last post by iMo on Today at 10:39:28 am »

So - I've desoldered the 324, it is TI's LM324.
Soldered in the gold plated socket. I have not found the 324 in my junkbox, so now using TL084 (TI).

CV - as in my schematics.

CC - 100pF in the fb and 1k5 sense, added a 100nF decoupling

The circuit behaves differently:

1. with CC engaged no oscillation, noise below 20mVpp at CC's opamp output
2. with CC disengaged and loaded (2.2A, 18.7V):
a. when PSU switched on there is 30-40mVpp 270ns period oscillation at CC's output, it slowly decreases to 20mVpp, sometimes disappears (noise below 10mV at CC's opamp output) and appears, it disappears when touching output of the 741 or the feedback of the 741
b. when the load is inserted (2.2A 18.7V) the oscillation starts again at 30-40mVpp, then within aprox 15secs its amplitude goes down and disappears (noise below 10mV at CC's output), but still sensitive..

The TL084 gets pretty hot (+12/-12V).

A really mysterious stuff, indeed

I have here a different 084 and a TLC274, I will also try to find a 324 somewhere as well..

8

Cooking / Re: [US] I require chicken salt

« Last post by digger on Today at 10:39:10 am »

IMHO, this type of prescriptivist nonsense is the sign of someone who may be a great scientist, but is not a great cook.

i would say that the best way to get good at cooking is practice (experience).

i find a strong attention to detail, taking detailed notes (and making recommendations for yourself for next time after the meal is done), gravimetric measurement, etc are very valuable as a home cook.

you're right that some inputs are a moving target, but that doesn't negate the value of my approach. i would not champion it if i did not know from experience that it has great value.

if you extend your argument to a logical extreme, it would seem to suggest that any recipe measurements are unhelpful to a home cook. it should be easy to see that more accurate, reproducible measurements can only help with recipe reproduction and communication despite variances in inputs and environmental conditions.

i also do not think that it makes me inflexible. it's not smart to assume someone like me can't just wing it

having an eye/feel for things and being able to document/communicate things are complementary skills. i don't get why you see them as skills in opposition of each other.

She responded simply: “you just add enough!” Back then that confused me.

this is a sign of an experienced cook that lacks documentation/communication skill.

I know people who cook this way, and while they’re certainly successful at cooking, they aren’t flexible cooks, and struggle to correct things when something isn’t cooperating.

this is a sign of an inexperienced cook (or lacking recent experience) who relies on his or her documentation skills as a crutch.

9

Test Equipment / Re: FNIRSI-1013D "100MHz" tablet oscilloscope

« Last post by Atlan on Today at 10:36:21 am »

The design of the entrance is terrible.

The line should be aligned with the cursor of channel 1 yellow or 2 blue. (putting a photo of the trigger cursor here is pointless - yes, I know there is a small inaccuracy, maybe I'll fix it one day)

To align the channel lines:
A basic calibration must be performed through the menu. (you can do this whenever you want, nothing is required.) You should do this every time you see a deviation of the line from the channel cursor. (you should ALWAYS do this calibration before calibrating the input dividers and calibrating the DC offset)

The center line (channel lines) is shifted by heating the oscilloscope and discharging the battery. Therefore, there is a possibility of basic calibration.

In the DC mode, it is more complicated with the centering of the channel lines.
(however, you didn't put the photo I asked for - 3V signal with 0V offset + photo of diagnostic screen)
If any DC offset is present, it will be recalculated to shift the line from the channel cursor. For example, my cheap Chinese generator does not have a 0V offset on the output when set to 0V offset !!!!

If you try basic calibration (disconnect cables, probes from inputs), the lines should align. In AC mode for sure.

In the photo I see DC offset=6, this can cause a shift, the output of your generator may not give 0V offset, try to connect the signal to the oscilloscope through a 100n capacitor, and press autosetup again, if the lines align.

10

Power/Renewable Energy/EV's / Re: Alternative to microinverters

« Last post by Siwastaja on Today at 10:28:50 am »

I genuinely have no idea why suddenly home energy storage is being viewed as a green alternative, on a global scale, as a solution.
Dave's installation is a prime example, he barely uses a few dozen percent per day, once. It's not efficient usage of batteries.
The same batteries used in a device on utility scale could be sized to charge and discharge several times in a day and serve several households.

I wholeheartedly agree. 99% of home battery installs are probably crippled like this, running small DoD% and small number of cycles per day. In Finland for example they sit 3 months disabled, during which the need for grid load balancing within the day is very real, and you can also get some very real money out of it.

But no, expensive high tech sits unused in most homes.

This is also exactly why our control box gets sold and installed... but it's still niche. We have surprisingly few competitors and most of the batteries are sold without any smart control, just for PV timeshift.

I mean, even with smart controls it is very hard to have batteries make financial sense. So our first simple algorithm reduced the payback time from 100 years to 50 years, and we are hoping the next better algorithm I'm working on gets that in range of 20-30 years. Then if we are able to sell our customers into reserve markets of frequency markets, it might be able to almost make financial sense, but...

As I always say, there are better low-hanging fruits. Like controlling EV charging and electric heating/hot water on/off based on those same market mechanisms one controls battery with. You can't export (sell to grid) but financially sane sell events are pretty rare anyway and make a small, maybe single-digit % of total. Juggling the timing of "self-use of PV" vs. "import" vs. "self-use of imported" is equally possible with aforementioned simple loads (even just relay control), you don't need a 5000-10000 EUR battery to do that.