Recent Posts

1

Test Equipment / Re: TinySA Ultra launched

« Last post by erikka on Today at 03:03:47 pm »

PLL's locking after the step
I do not mute the output as this would slow down the maximum sweep speed and created larger gaps which you will hear as stronger clicks.
Any stepwise sweep will always have some form of artifacts

Can you explain why these may be a problem?
Or is this just curiosity because of what you saw on the DSO?

2

Beginners / Re: Convert US standard 115V to International 230V

« Last post by wasedadoc on Today at 03:01:32 pm »

If the circuitry after the capacitor has no problem with the voltage dips between refreshes from 120 V 60 Hz supply, there will be plenty of headroom for the slightly deeper dips when the supply is 230V 50Hz.

Except half of Japan, does anywhere else have 100 V 50Hz supply?

3

Test Equipment / Re: TinySA Ultra launched

« Last post by KungFuJosh on Today at 02:59:19 pm »

The tinySA does not do a continuous sweep but sweeps in discrete steps with possible silence in between. Set the scan speed slow and you will see the step

What are the random frequencies that appear between steps?

4

Power/Renewable Energy/EV's / Re: Power supply EMC document is erroneous?

« Last post by AnalogTodd on Today at 02:54:46 pm »

Simplification and idealization is used so much in our world to make solving problems easier (not to mention teaching of difficult concepts). Do you take into account the few milliohms of impedance between every connection in a circuit? Very few people do in their designs. Once you get into the 'real world' you often run into these bits cropping up and throwing off your design. The difference between a good designer and a great designer is in being able to figure out what is happening and learn from their mistakes.

How many companies out there just have good designers that don't understand real world implications? You can usually tell by the number of failed projects being left in their wake. Didn't design it with proper filtering? It doesn't pass certifications and it goes on the junk pile when someone can't figure out why it fails. I was involved in figuring out that 40dB drop in supply rejection on a linear regulator that I showed. It could have been left alone and written off as circuit models in SPICE not being as accurate as possible. Instead, we spent time playing with the circuit and found out that the MLCC we had at the input of the regulator made things worse, then spent time figuring out WHY it did so.

In that same vein, there are also people who are great for writing this stuff out in technical articles and including the real world issues. There are also people who are crap at it. Who are authors that you trust their writing and circuits? Personally, I think Jim Williams and Bob Pease were great at getting the details that mattered included in their writing. I've written articles and app notes over the years. I was fortunate to have some of the best engineers in industry review them before publication. I've also been the reviewer of writing that others have done and found fundamental flaws in their arguments. If you don't have the right reviewers going over a technical piece those flaws may never get discovered. I will be one of the first to admit my writing isn't perfect--sometimes you re-read everything you wrote over and over and see what you meant for it to say instead of what it actually says. You can't see the forest because of all the trees blocking your view.

So why spend all this time and energy pointing out the mistakes others make? There are plenty of companies out there trying to do things based on those mistakes and the circuits end up in the trash. Instead, make a better circuit to sell. Are you worried that younger engineers may read this stuff and make mistakes based on it? Then be a mentor to engineers directly instead of in an anonymous internet forum.

Engineering is about designing the best possible solution for a problem at a price point that maximizes profits. A simpler solution may not work as well as a more expensive one, but it may be 'good enough' that it gets the sale. There are plenty of engineers out there who will design the low-end stuff that sells at profit margins that are barely sustainable and will make ends meet based on quantity sales. Those of us who design the higher end solutions don't get the number of sales as the low-end guys, but we make enough in profits from it to be comfortable.

5

Projects, Designs, and Technical Stuff / Re: Corrosion on DIP pins

« Last post by edavid on Today at 02:52:51 pm »

Just an additional annoyance: MOSTEK is known nowadays to have a relatively high incidence of memory rot, which renders the IC unusable due to internal degradation even on ICs that are physically in good shape.

That's a problem with mask ROMs like the MK36000.  Aren't the ICs in the photo DRAMs?

6

Test Equipment / Which Arbitrary function Generator Can Hold after generate Arbitrary waveform

« Last post by ElectronicABC on Today at 02:49:07 pm »

For Rigol DG1062Z,output  Arbitrary waveform in *.raf then cycle again，but how to hold after the latest point?

and I test the Burst mode ,but there is 1ms zero voltage Pulse before it go to Idle (as set ) level.

7

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by mawyatt on Today at 02:40:53 pm »

Generating a precise & stable amplitude (and frequency) square-wave isn't difficult, see below.

https://www.eevblog.com/forum/testgear/ac-rms-dmm-tests/

However extracting a precise & stable sine-wave from this square-wave may be more difficult than expected.

Since a waveform's rms value is the sum of all the individual components that make up the waveform, extracting the fundamental from a squarewave requires removing all the harmonics to a level sufficient to guarantee the "precision" of the leftover sinusoidal like waveform relative to a pure sine-wave.

Removing these harmonics entails utilizing a Low Pass filter, which must attenuate the harmonics to sufficient levels to meet the desired precision and stability of the desired resultant waveform but not attenuate the fundamental to effect the desired result.

This may become a tall task if one seeks a high level of precision, and even more so if one demands temperature and time stability. Sure one can "calibrate" the LPF and squarewave but then the circuitry must maintain an acceptable level of temp and time stability after calibration. As shown in the link above, creating a precise low frequency squarewave that is stable in frequency and amplitude over temp and time isn't difficult, converting to an acceptable precision sinusoidal waveform may be another story!!

Best,   

8

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by Alex Nikitin on Today at 02:38:18 pm »

Have a look at how it is done in the Fluke 510A AC Reference circuit, it compares the amplitude to the level of a DC reference (easily set with a good DC voltmeter) and provides a ppm-level of amplitude accuracy and stability on AC.

Cheers

Alex

9

Beginners / Is it safe to store CMOS devices in the AideTek ESD Boxes

« Last post by watchmaker on Today at 02:31:19 pm »

I now have some CMOS devices in ESD tubes and envelopes.  I would like to develop a rational storage system. Are the AideTek ESD boxes safe or do I still need the black foam?  The Learning Art of Electronics offer I purchased made this an issue much sooner than I was ready for.

Also, since I tend to order by 5s (at least) from DigiKey, what are the storage strategies for tubes?

I am thinking of categorizing by logic chips, op amps, regulators, etc. and then call number.

Regards,

Dewey

10

Manufacturing & Assembly / Re: Brief review of the Zhengbang ZB2520HL reflow oven (T-962A alternative)

« Last post by MR on Today at 02:27:58 pm »

Cheap IR heater ... no thanks. might be okay for some easy PCBs without special requirements. And no one can convince me that unshielded IR will be good (or good at all for components).
Conventional is much less troublesome, the next level of that seems to be Vapor Phase Soldering.

One of those IR modules probably costs around 5-7$ (just that you know what the engine of that IR heater costs). Multiply it with 4 and that's it the rest is enclosure and the controller.