Recent Posts

1

General Technical Chat / Re: H5N1 bird flu and how we're risking another global pandemic

« Last post by ConKbot on Today at 02:12:34 pm »

Oh no, even chickens bad now, the only solution to save humanity is to switch to industrially produced protein supplement brick meals! Totally not because it's very very profitable for us to turn any garbage protein, fat, and carb source into kibble for humans.

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Projects, Designs, and Technical Stuff / Re: Homebrew Lock-In Amplifier

« Last post by shabaz on Today at 02:10:30 pm »

This won't meet the OP's needs, but it might be of slight interest to beginners: I created an educational project. I was hoping people could create new experiments with it to improve on my simple ones, but there's no traction (at least, I'm not aware of anyone trying it out).

The project is called Wave Miner (Github link) and has 10 starter experiments so far.

It uses a DSP board from AliExpress and a simple breakout board to BNC connectors (the photo shows it attached to a Raspberry Pi for programming the DSP; the Pi can be detached afterward).

The Gerber files for that breakout board are at that Github link. From the 10 starter experiments, experiment #9 is a very crude lock-in amplifier.

Here is a video demo of the LIA  (before I constructed the breakout board).


The experiments are very basic and for fun/learning rather than serious use, and the DSP used is extremely limited, but on the plus side, very little construction is needed (the breakout board is entirely through-hole construction for simplicity).

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

« Last post by mawyatt on Today at 02:10:18 pm »

We have both the Siglent SDS800 and the Rigol DHO800, well the Rigol is a clients that has run into financial difficulty, so likely to remain at "The Labs" for awhile.

We acquired the Rigol for said client and the plan was to teach them the DSO use for a specific application, so spent some time and became familiar with such.

Simply put, Rigol hit a Home Run with the DHO800 introduction, with the custom 12 bit Chip Sets, small form factor, nice screen (altho a bit dim), solid build, excellent UI, VESA, HDMI, nice probes and so on at a price point most could afford. As one popular Rigol Fanboy put it, "Game Changer"!! Which was true, this little Rigol DSO was quite remarkable in every respect, especially considering the price point!!

Needless to say we were impressed with this Rigol DSO, and this was our 1st direct "hands on" with any Rigol product, similar to our experience with our 1st "hands on" with our Siglent SDS2000X+ a few years back, both these folks have really done a superb job   

When the SDS800 was available we decided to spend our own nickel, well the Rigol so far has ended up on our nickel as well

Simply put, Rigol hit a Home Run with the DHO800 introduction, then Siglent hit a Grand Slam with the SDS800 introduction 

As good as the Rigol DHO800 is, and it's good, really good is every aspect, the Siglent SDS800 is just overall better IMO.

We have no brand preference, just have a preference for the best instrument for the task (know thy instrument so to speak), and when one factors in cost, the best value instrument for the task!!

Bottom line is you can't go WRONG with either the Rigol or Siglent, but as 2N3055 mentioned the Siglent is the more "Pro Like" Instrument, and more in-line with making quality/trustworthy measurement/observations rather than just playing around and tinkering, which is fun BTW    

So when we reach for a DSO, now we reach for the SDS800, usually with the Rigol probes tho (these are really good, better than the Siglent IMO) 

Anyway, how either one of these can be offered at this price point is remarkable and a tribute to both Rigol and Siglent, but honestly from a well seasoned old Pro who's used every piece of TE imaginable, one would expect the Siglent to cost ~10X......yes it's that good!! Heck one would expect the Rigol to cost ~3X also!!!

BTW we are NOT open for doing direct comparisons, we'll let that reside in the hands of others!!

Of course, as always, YMMV!

Best,

 

4

Repair / Re: Rigol DP712 Output Shorted; Fuse? / I Screwed Up

« Last post by Harry_22 on Today at 02:08:03 pm »

You are absolutely right, the SCR should short the output if the voltage exceeds a set threshold for any reason. This is confirmed by the cooling radiator designed for long-term operation. To discharge the energy stored in 470 uF capacitor a radiator is not needed.
Topic starter sent us the PS settings that he installed. We see that the OVP was 13 volts and the battery was 11.5 volts. In this case, the OVP should not have worked. Only the current through the shunt could exceed the OCP set value. But it flowed in the opposite direction and I'm not sure that the reverse current is measured here.

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

« Last post by Majorassburn on Today at 02:05:21 pm »

What could be a proved single opamp for a wien oscillator?

Anything with sufficient frequency response, and output voltage swing, and drive capability.

Since you still haven't bothered to tell us those parameters, how do you expect us to help you?

In addition, ponder the second paragraph here.

More thread-choking negativity and useless crap from tggzzz. 
He's a real thread-killer if I ever saw one!

Your question about op amps?  I use T.I. OP07's with excellent results in my low frequency sine wave oscillators.
Data Sheet link: https://www.ti.com/lit/ds/symlink/op07c.pdf?ts=1714331934514&ref_url=https%253A%252F%252Fwww.google.com%252F

Also, check out the numerous TI App Notes for oscillator designs with sample circuitry you might use as starting points. Best Regards.

The context is these threads from MajorAssBurn:
https://www.eevblog.com/forum/buysellwanted/fs-affordable-dmm-checkers-ac-reference-dc-reference-ohms-reference-etc/msg5463700/#msg5463700
https://www.eevblog.com/forum/metrology/affordable-useful-ac-dc-references/msg5438690/#msg5438690
Anybody with too much time on their hands can read those. They will, no doubt, notice that many people have made negative comments about MajorAssBurn's claims in those threads.

BTW, it isn't good practice to read the first couple of posts in a thread and then jump to conclusions without reading the rest of the thread.

I have this mental image of tggzzz sitting in his week-old undies and moth-eaten robe, in the corner of his tiny, gloomy, cold-water flat, in a poverty-stricken slum section of Birmingham, pecking away at his twenty-year-old Pentium computer while desperately searching forums and threads for topics wherein he can spew out his unwelcome drivel and negativity and display his legendary (in his own mind) philosophical and technical superiority as compared to the woefully ignorant and uninformed commoners who participate in these threads looking for useful suggestions from fellow members, as he, the self-ordained master of thread imposition, reflects within himself how utterly failed as a human being he is, as he seeks out these thread-killing opportunities so as to feel somewhat compensated for his lifelong worthlessness and complete failure to achieve anything noteworthy or meaningful.

Now, with those facts in mind, I will ignore all further written diarrhea that tggzzz dumps in various discussions from now on. 

6

General Technical Chat / Re: H5N1 bird flu and how we're risking another global pandemic

« Last post by magic on Today at 02:03:01 pm »

Nice reddit drama thread.

You forgot to add that you don't intend to bash the US because China uses industrial farming too and mention something about chipageddon to make it electronics-related

7

General Technical Chat / Re: H5N1 bird flu and how we're risking another global pandemic

« Last post by Zero999 on Today at 01:59:35 pm »

It's true there will be another pandemic and nothing has been learned from the one just gone, but isn't this a bit too off-topic?

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Projects, Designs, and Technical Stuff / Re: Control of 2 CAN Open DS402 motors on a single shaft

« Last post by max_torque on Today at 01:57:23 pm »

Ok, i'm gonna ask another "stupid" question: Does the system actually NEED two seperate motors?  It's going to be cheaper, simpler, and more robust to just fit one motor to do the work if you can!

Ie, rather than have to invent some complex control archecture to suit some dynamic load you may never get a chance to properly validate, just simplify the system to one drive node!!

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Projects, Designs, and Technical Stuff / Re: Build or buy? Multi-level vessel temperature logger

« Last post by max_torque on Today at 01:55:06 pm »

Aside: This ^^ has been done many times!  I use an optical fibre temperature sensing array to measure various temperatures inside a running high voltage permanent magnet machine. Works by firing a lazer down the fibre and measuring the phase shift that is driven by a temperature dependant scintilating end "reflector"



Back with the OP, whats best probably depends on how dynamic the system is going to need to be, ie how quickly temperature changes and how fast it must repond.  For slow systems then a thin pcb with NTC resistors (or serial output temp sensor ICs etc) along it's length could be easily sealed into a length of food grade silicon tube pretty easily.  That silicon covering is going to limit thedegree of isotropic conformity to it's surrounding as compared to a more thermally conductive protection medium (ie stainless steel etc)

Again, you need to consider just how precise, accurate, responsive and complex the measurement device actually needs to be!

10

Test Equipment / Re: Siglent SSA 3021X... Ooops

« Last post by Joel_l on Today at 01:51:55 pm »

Looking at it, there are a couple I think I can do, though I have always wanted a power meter....

Problem is still the flakey nature of it, might pass this time and not the next.

I will do the ones I can for a baseline. I always thought the noise floor on mine seemed high, so that will be a good one to go through.

Thanks