Recent Posts

1

Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by iMo on Today at 02:27:07 pm »

I've updated above table, there are RDN and RDP "fixed" clocks (5 as an example), and the zero values returned by RDN and RDP (an example), where the RDP returns always at least "1" (we make the decrement before the comparator check).

Also my understanding is the rundown process above returns max 31+1 "net" counts, where one count == 2 SM clocks.

2

RF, Microwave, Ham Radio / Re: MFJ Shutting Down Production and Going Out of Business

« Last post by pienari on Today at 02:26:45 pm »

I have owned a few products but each time has been a disappointment.
MFJ is been late all the time in product development.

3

Beginners / Re: Connector name

« Last post by tooki on Today at 02:24:09 pm »

What zanfar said: we cannot possibly begin to identify it based on the uselessly blurry photos (and lack of other info) provided. There are literally thousands of connector series out there, and many of them look extremely similar, especially without any scale. (Some essentially are scaled up/down versions of others, so without scale, they are the same!) You need to provide sharp, well lit photos from every side, and either a carefully placed ruler in the photos, or provide accurate measurements. Also, give us context of what the connector is used in: someone might already know what it is.

Just to be clear, though, pin pitch is NOT the distance between pins, it’s the distance between pin centers.

4

Security / Re: Microsoft repackages apps with a telemetry .NET wrapper

« Last post by PlainName on Today at 02:23:10 pm »

getting panties in a twist over nothing…

Microsoft forcing telemetry on you is 'getting your panties in a twist'? That only seems innocuous compared to them not limiting it to the Store.

5

General Technical Chat / Re: Why Circuit Breakers DON'T Protect People (electric shocks)

« Last post by AVGresponding on Today at 02:21:55 pm »

RCDs also prevent fires.  One of the original justifications for RCDs was detecting rodent damage to tasty cables.  A rodent could chew through a cable and create a path from live to earth which might be insufficient to trigger an MCB but the imbalance would quickly trip an RCD.

This is a particular issue in lofts.

https://www.electrical-installation.org/enwiki/Protection_against_fire_due_to_earth_faults

Yeah, take that article with a pinch of salt; it's by Schneider Electric.

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Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by Kleinstein on Today at 02:19:32 pm »

The main scale factor for the rundown is still the same as the runup. So ideally just the number of clock cycles per run-up set. It's only small corrections from asymmetry and settling effects during runup that may apply. Especially the correction for settling may not be needed unless the modulation is really fast (I don't need it at 8 digit resolution). The way with rundown may have 1 or maybe 2 correction constants, while the resudual ADC directly needs a pretty stable auxiliary ADC and a more critical cal factor there. Getting full 12 bits from the residue is pushing it: there is extra noise from the 2nd conversion and the gain factor and integrator capacitance have limited stability. After rundown the auxiliary ADC is something like 30 times less critical.

The rundown part is usually quite stable, as it uses the same reference as the runup.

For just 6.5. digits (with 1 or 10 PLC) just the resudue ADC can be OK. When aiming for more (especially high resolution already with short integration like 1 ms) the extra resolution from the rundown can really help. Getting more resolution from faster modulation is challanging on the integrator.

A downside with the extra rundown is a bit of extra time needed and also more code, which may be an issue with the limited code space for PIO. One may want a bit slower modulation or at least longer minimum pulse lengths to avoid the settling effect - for the resolution the fast runup is not longer needed.

7

Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD

« Last post by 2N3055 on Today at 02:18:45 pm »

I'm not a somnambulist

Are you sure you haven't sleep walked into a manual or two? 🤣

A somnascriptor ??

8

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Fungus on Today at 02:16:34 pm »

FWIW you'll get the same with a hardware filter, too.

eg. I've seen the "2.5x rule" appear when sending a PWM signal into an RC filter.

My PWM frequency was 31.25kHz and the "AM" effect appeared right around 12.5kHz  (31.25/2.5=12.5). 

This image shows where it comes from - the amplitude changes depending on the phase difference between the samples and the signal:

9

Manufacturing & Assembly / Long thin part rotating during placement.

« Last post by loki42 on Today at 02:14:14 pm »

I am placing an connector with my pnp machines. I have tried multiple heads with different styles of nozzles.  The connector is df40hc(3.0)-100ds-0.4v(51

from Hi rose. With the unsettling lack of ). I'm having trouble with them being placed with the wrong rotation.  I'm unsure if a different nozzle choice would work better but the pickup surface is tiny and the tape isn't easy for a gripper nozzle to get into.  I'm unsure why they are moving.  My other parts are placed with correct theta.  Maybe the small rotation errors are due to insufficient board support and the board bouncing after placement?  Maybe I should force them to be placed last,  but I'm just guessing.  Had anyone had a similar issue?

10

RF, Microwave, Ham Radio / Re: MFJ Shutting Down Production and Going Out of Business

« Last post by pdenisowski on Today at 02:14:09 pm »

I think a lot of the newer available things like the NanoVNA and less of a need for brute force transmitting like the olden days (think FT8) really made a dent in their product line.

Aside from being harder to read in direct sunlight, the NanoVNA is - in my opinion - much a better antenna analyzer than the MFJ analyzers ever were.

There has definitely been a move in the hobby towards computer + store-bought rig (especially for newer hams), which I'm sure didn't help MJFJ's sales.  There are also a lot more companies now that MFJ had to compete with for things like tuners (especially auto-tuners), antenna analyzers, digital interfaces, power supplies, etc.  Even as late as the early 1990s, MFJ was just about the only game in town (so to speak) for many ham radio accessories.

I'm not surprised that Mr. Jue wants to step away from the company at 80 years of age.  And, frankly, I'm not surprised that they did not (try to?) find someone to take the business over.  But it is very sad to see them close up shop - will have to stock up on anything I might need before they close up for good.