Author Topic: GW Instek MDO-2000E  (Read 12139 times)

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Offline MrW0lfTopic starter

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GW Instek MDO-2000E
« on: August 08, 2017, 06:31:14 pm »
« Last Edit: August 08, 2017, 07:06:40 pm by MrW0lf »
 
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Online nctnico

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Re: GW Instek MDO-2000E
« Reply #1 on: August 08, 2017, 07:24:08 pm »
Interesting! This way you can have a complete test solution from a single piece of equipment. IMHO it seems geared towards educational situations.
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Offline MrW0lfTopic starter

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Re: GW Instek MDO-2000E
« Reply #2 on: August 08, 2017, 07:33:05 pm »
Reading manual:

Range Start: -250MHz ~ 499.995MHz
Stop: 500Hz ~ 750MHz
Span: 1kHz ~ 500MHz


Span:RBW
5000:1...1000:1 auto or manual


Up to 4 trace types (Normal, Average, MinHold, MaxHold) at same time, source is any (one?) analog ch.
I was thinking for some time now that something like this can and should be done (FFT with more conventional SA style approach) :-+

Edit: Something does not compute. Why max start 499.995MHz... Maybe they mixed up Stop and Span in manual.
« Last Edit: August 09, 2017, 11:52:00 am by MrW0lf »
 
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Offline saturation

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Re: GW Instek MDO-2000E
« Reply #3 on: August 10, 2017, 12:37:02 am »
GWI really leverages its Zynq development, adding "modules" to create forks in the DSO line.  Like nctnico, I do see this in particular focused on the EDU>> factory floor market, as with an AWG, DMM, DSO, PSU and SA rolled into one, really saves on school bench space but some of the specific instruments are not outstanding for the overall cost [ by list EUR1700 for the 4 ch 200MHz top line model], in particular:

The SA, spurious response is near that of the software FFT in the 1000B, even if overall its better than an FFT
I'd hate to damage an entire DSO using what is spec'd to be a $50 DMM, or lug the whole around for just a DMM
The PSU is like those in powered breadboards, and at most for TTL, somewhat limited for experimenting with robotics motors
Best Wishes,

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Offline MrW0lfTopic starter

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Re: GW Instek MDO-2000E
« Reply #4 on: August 19, 2017, 05:08:18 pm »
Spectrum analyzer demo on the MDO-2000E:

Not very technical... all shown could done with regular FFT also.
 
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #5 on: March 12, 2018, 09:23:32 pm »
Interesting! This way you can have a complete test solution from a single piece of equipment. IMHO it seems geared towards educational situations.
I've just ordered two for our embedded SW engineers and an extra one for my home lab.
Desk space does get crowded with a couple of 27" monitors. :D

It should be quite nice for debugging HW abstraction layer and the HW it self.
The AWG is nice for input signal simulation and the HW guy can simulate CPU output signals before the SW is ready.
The only missing thing that would be nice to have is an electronic load to test the outputs. :P
But to be fair - 6 instruments in one is quite a bargain for €1410. :-+

It's also a fairly cheap LabVIEW all-round I/O device for automated testscripts. :D

Best regards
Soren

PS: I haven't seen any comments on the built in self calibration using the CAL output on the back.
It would be a pretty good business case to include a bit of redundancy and good diagnostics to have a reliable CAL output.
I would gladly pay $100 extra for this if I'm saving $1000/year in external calibration and don't have to be without the instrument for several weeks.
Do any of you know about the reliability of this output? :-//
It would be really nice to be able to do self calibration in 20 minutes any time you like check the accuracy (and skip the calibration bill & being without the instrument).
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #6 on: March 12, 2018, 11:58:27 pm »
The problem with the self cal is the lack of traceability.  If you have enough scopes, buying a scope calibrator and sending it out for cal makes good sense.  With the Instek 2000E line, Leo's pulser and an FFT will get a lot of data.  The only shortfall is the higher ranges on the attenuator which are also the most problematic.

I've been meaning to see what the cal signal looks like.  That might make a good evening amusement.  I really don't feel like doing any heavy lifting and I'm back to "waiting on parts".   In this case I need to order some too. I'll see how long that takes.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #7 on: March 13, 2018, 06:17:07 am »
Yes, traceability is key if you CAL output is not fail-safe.
The big question is: how much would it cost to disrupt the calibration industry?

You need to build in some redundancy and good diagnostic coverage on the CAL output, but it might not be terribly expensive to do that.
Adding $10 worth of HW would not be a problem because the function is worth much more.

With a careful design it should be possible to build a fail-safe CAL output with enough redundancy and diagnostics to detect when something is wrong with the CAL output signal. The circuit should avoid any common cause failures, be able to detect any possible failure and deny self calibration in case of a failure in the output or the diagnostics circuitry.

They might not have gone to this length with the GW Instek design, but I can't even imagine how much value there would be in disrupting the calibration industry.
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #8 on: March 13, 2018, 01:37:17 pm »
It would not be hard to disrupt the calibration service industry.  Whether or not that is good is another question.  Watch the video of Dave's visit to the Keysight cal lab.  However, $10 of HW would allow extending the cal interval out to several years.

I've not investigated what a Fluke scope tester does, but I did know  the procedures for a Tek 465 and had acquired most of the kit for that.

Most of the traditional analog scope tests can be replaced by some precision input signals and DSP routines.  For example, while rise time is an important aspect of BW it does not quantify the flatness of the spectrum.  But with a signal such as Leo Bodnar's 40 pS pulser  the spectral flatness can be recovered to ADC precision via an FFT.   The traditional method was a signal generator and a selective level meter in addition to a Tek 106 pulse generator.

As an example, a simple RC circuit and some mathematics are sufficient to characterize and correct ADC errors. The cost would be the flash to store the code.  However, the non-recurring engineering cost is not trivial.  What I'd consider a proper state of the art job would run $20-30k.  That's based on  using  a sparse L1 pursuit solution. It would only take me a few days to prototype the code, but implementing a production version is a lot more time consuming.  You have to make sure you have found and tested *all* the edge cases.  It can take days to identify the edge cases and days more to figure out how to test them.  And there is no such thing as self documenting code.

I wrote a couple of 15,000 line libraries that had no bugs reported in almost 20 years of use before being retired because it was obsolete.  This was part of a 500,000 line port of old FORTRAN code from VMS to Unix.  The first year in service we had fewer than a dozen user submitted bug reports.  It asymptotically  approached zero because we had a large regression test suite which ran every time we built the system on multiple platforms.

The Instek uses the Zynq 7010 for the main functions.  There is a Spartan 6 which appears to be for handling the LCD and front panel chores.  I believe the Siglent also uses the Zynq.

I  managed to pick up a GDS-2072E for $244 in an Amazon NOS clearout.  I'm assembling a development environment consisting of a Zybo Z7-20 and a BeagleBoard X15.  As I have no FPGA experience I got a MicroZed specifically for the Avnet tutorials.  All of this is for the purpose of developing an open source firmware for Zynq based instruments.  That will take a few years, but I need a good project.  There is no work for people like me in the oil industry (too old and over qualified) .

As it happens I spent the last 3-4 years studying sparse L1 pursuits which is a more general description of compressive sensing.  There are no instruments on the market that offer that yet.  A prototype was done by Nicholas Tzou at Georgia Tech for his PhD which he finished in 2014.  There appear to be many advantages to applying sparse L1 pursuits in a DSO besides reducing the data volume.  It's interesting and I think that an  FPGA compressive sensing IP has good commercial potential.  People will tell you they love you for free, but if they give you money, you know it's true.

I've posted a bit about this, but all it's attracted is a bunch of derision from people who do not know and will not read the mathematics.  Aside from not knowing the work of Candes and Donoho at all, they don't actually know Fourier, Wiener and Shannon well.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #9 on: March 13, 2018, 02:38:24 pm »
It would not be hard to disrupt the calibration service industry.
...
Most of the traditional analog scope tests can be replaced by some precision input signals and DSP routines.  For example, while rise time is an important aspect of BW it does not quantify the flatness of the spectrum.  But with a signal such as Leo Bodnar's 40 pS pulser  the spectral flatness can be recovered to ADC precision via an FFT.
I think it would be a pretty good business case to do this as a scope manufacturer. :-+

You don't need to find all possible errors on an instrument - just the ones that might go unnoticed by an operator like increasing voltage and frequency tolerances.
An LCD or a button that doesn't work would be noticed by the operator anyway.

You do need a precision input signal with redundancy and diagnostics, so that you can detect if it is no longer as accurate as required.
The test needs to uncover the same errors as the standard calibration procedure - no more and no less.

I would certainly fork out some cash for a function like that or choose an instrument over one that didn't have it. :)
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #10 on: March 13, 2018, 02:56:51 pm »
It would not be hard to disrupt the calibration service industry.
...
Most of the traditional analog scope tests can be replaced by some precision input signals and DSP routines.  For example, while rise time is an important aspect of BW it does not quantify the flatness of the spectrum.  But with a signal such as Leo Bodnar's 40 pS pulser  the spectral flatness can be recovered to ADC precision via an FFT.
I think it would be a pretty good business case to do this as a scope manufacturer. :-+


They are doing  it.  The self calibration and signal path corrections are examples.  They may be doing a lot more of it in manufacture than is widely known.
 

Online nctnico

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Re: GW Instek MDO-2000E
« Reply #11 on: March 13, 2018, 08:26:17 pm »
Yes, traceability is key if you CAL output is not fail-safe.
The big question is: how much would it cost to disrupt the calibration industry?
A lot. The CAL output is nothing more than a 'known' signal an oscilloscope can use to do a quick verification of ADCs and input attenuators. It is a very nice to have and for some high-end oscilloscopes it can mean the difference between needing a lot of equipment (Tektronix TDS500/600/700 series for example) or just a BNC cable (Agilent Infiniium 54000 series for example) to adjust it.

Nevertheless a self calibration/adjustment isn't traceable to any standard. So even with a CAL output you'd need to verify the oscilloscope using known-good equipment which has a traceable calibration if you want to absolutely sure the oscilloscope meets it's specifications.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #12 on: March 13, 2018, 11:12:57 pm »
Nevertheless a self calibration/adjustment isn't traceable to any standard. So even with a CAL output you'd need to verify the oscilloscope using known-good equipment which has a traceable calibration if you want to absolutely sure the oscilloscope meets it's specifications.
Traceability to a known standard is only needed if it is possible for the reference signal to become inaccurate without being able to detect that it has become inaccurate.

If it was possible to design an accurate reference signal and have fail-safe detection of any deviation outside the specified tolerance, then you wouldn't need any traceability to a known reference as long as the signal is within specification. You would need to avoid common cause errors in the redundant diagnostics circuits.

The disruption is the removal of the need for traceability to a known reference. :-/O
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #13 on: March 14, 2018, 12:56:27 am »
You can't remove the need for traceacability. Calibration is the process of verifying the system against the international standards.  There are different classes of calibration, but what a calibration lab offers is instruments which they in turn send to the national labs for calibration.

If the instrument performance can vary over time, so can a built in calibration reference.  The real key to lowering calibration costs is a low cost calibrator that can be checked on a regular basis at low cost.  An ASCII file of measurements of one  of Leo Bodnar's 40 pS pulsers measured with a calibrated DSO combined with some DSP work will handle a very large chunk of the DSO calibration tasks.  There is no reason that having such a device measured on a calibrated instrument should be expensive.    Nothing is being adjusted.  All that is required is to connect the device to a 10 GHz or faster scope,  run a program on a PC and store the measurements in flash on the device.

Designing such a device is not trivial, but it's not that hard either.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #14 on: March 14, 2018, 07:34:23 am »
You can't remove the need for traceacability.
...
If the instrument performance can vary over time, so can a built in calibration reference.
The big question is: can you build a reference that cannot vary undetected?

If you can build a circuit that can detect any deviation outside a defined tolerance range, you can use it for calibration if it is within range, and display a message that it has to be shipped for external calibration if it is outside the defined tolerance range. ^-^

I agree that a very well defined square wave can be used to calibrate the input channel of a scope over a wide bandwidth range. The key issue is to make a circuit that can detect a variation in this reference signal with a very high propability. The propability of failure detection must be higher than the propability of an instrument going out of spec between calibrations.

You would need redundant channels with separate power supplies to remove the possibility for common cause failures, but if this could be constructed to be cheaper than an external calibration you would have a good business case. Not having to be without the instrument and the ability to do a calibration any time you're suspicious of a failure would be an added bonus.  :-+
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Online nctnico

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Re: GW Instek MDO-2000E
« Reply #15 on: March 14, 2018, 10:28:41 am »
You can't remove the need for traceacability.
...
If the instrument performance can vary over time, so can a built in calibration reference.
The big question is: can you build a reference that cannot vary undetected?
NO! Not with 100% certaintity.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline rhb

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Re: GW Instek MDO-2000E
« Reply #16 on: March 14, 2018, 01:06:10 pm »
You can't remove the need for traceacability.
...
If the instrument performance can vary over time, so can a built in calibration reference.
The big question is: can you build a reference that cannot vary undetected?
NO! Not with 100% certaintity.

Well, actually you can.  But you have to calibrate it at regular intervals to detect the deviation.  This is what the national and other primary standard grade labs do.  They constantly compare their standards against each other and other laboratories.  Comparisons to other labs are typically done with transfer standards.

Read the metrology thread.  There's a set of transfer standards that circulates among amateurs.

The existing built in functions can correct a lot of things, but they can't correct errors in the builtin references.

There's an old saying, "Go to sea with one watch or three."
 

Online nctnico

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Re: GW Instek MDO-2000E
« Reply #17 on: March 14, 2018, 02:03:59 pm »
I think SWR is asking whether it can be done without comparing (calibration) to known-good references and then the answer is still no.
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #18 on: March 14, 2018, 02:21:26 pm »
Which is what I said.  If you don't check it the variation can't be detected, but that's not a solution.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #19 on: March 14, 2018, 02:49:03 pm »
NO! Not with 100% certaintity.
I agree - not with 100% certainty, but then again calibration doesn't give you 100% certainty.
Your scope could go out of calibration on the way back from the calibration lab.
Although the propability that this is going to happen is quite small it is not zero.

I don't think you can ever achieve 100% certainty, but if you can achieve an acceptable high level of certainty on par with what periodic calibrations can deliver, then it should be an equally good solution - just at a much lower cost because you remove the manual work of doing a calibration and all the overhead of running a business that perform the calibration.
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #20 on: March 14, 2018, 03:19:18 pm »
The existing built in functions can correct a lot of things, but they can't correct errors in the builtin references.
They might not need to correct it (fail operational) - it might be enough to detect it (fail safe).
All you need is a message that your instrument is no longer within the specified tolerances, and the message has to have a high level of reliability - not 100% but pretty close to that. :)
Quote
There's an old saying, "Go to sea with one watch or three."
Thats a fitting example using redundancy as a mitigating factor - diagnostics is another useful tool. If the three watches were of different construction (reducing common cause failure) that would further reduce the propability of all three failing the same way at the same time. :)
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #21 on: March 15, 2018, 03:01:12 pm »
Most of the traditional analog scope tests can be replaced by some precision input signals and DSP routines.  For example, while rise time is an important aspect of BW it does not quantify the flatness of the spectrum.  But with a signal such as Leo Bodnar's 40 pS pulser  the spectral flatness can be recovered to ADC precision via an FFT.
Thank you for the reference - that's a really cool device and I've just placed an order for one. :-+

As far as I could read in another thread it's got quite accurate TCXO timing, but there's no mentioning of the amplitude accuracy, so I assume that it doesn't use a precision voltage reference for the amplitude. That would only be for the gain calibration anyway, so it's perfectly fine for relative amplitude measurements over a wide bandwidth. It should be perfect for a 200MHz scope and I'm looking forward to playing with this. :D
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #22 on: March 15, 2018, 03:32:01 pm »
You may not like your scope's step response after you get it.  I was nervous about accidental damage, so I covered mine with a big piece of heatshrink.  I cut X's for the connectors, slipped it on and shrank it.

One of the goals of my FOSS Zynq DSO project is to implement filters in the FPGA that correct errors in the step response.  The step responses of my MSO-2204EA and GDS-2072E are awful.  Interestingly, the 100 MHz BW response of the MSO is almost identical to the step response of the GDS.  I need to plot them together for a closer comparison.  When I do that I'll calculate the amplitude spectra.

I cut down a heatsink to fit my MicroZed and glued it on yesterday, so I'm about to start work on Vivado and Verilog.  The heatsink took the slow boat from China but finally arrived.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #23 on: March 15, 2018, 03:56:11 pm »
That's some interesting projects you're working on. :)

I think I'll just 3D-print a small housing that fits the unit.
Thank you for the tip. :)
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #24 on: March 15, 2018, 06:04:58 pm »
Much nicer, but  you've got to have access to one.  Please consider posting the files to Leo's pulser thread.  I think others would be interested.
 

Offline SWR

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Re: GW Instek MDO-2000E
« Reply #25 on: March 16, 2018, 09:09:01 am »
I'll give it a shot and post the results when I have received the generator. :)
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #26 on: March 21, 2018, 08:15:52 pm »
I received the Leo Bodner pulse generator tonight ;D ... What a handy little device! :-+

It was measured at 32ps rise time and 27ps fall time.
Well below the specified 40ps. :)
Well done! :-+

I measured a rise and fall time of 1,22ns on the MDO-2204EX with a low end 50 \$\Omega\$ terminater on a BNC T-adapter.
All my RF terminators are N or SMA and I don't have a BNC through terminator, so that will have to do for now.
It should compare to an analog bandwidth of 287MHz which is above the specified 200MHz.
It would propably be a little bit higher with a proper termination so I'm quite satisfied with that. :)

It doesn't get warm so I'm going to print a small housing for it to protect the SMD components. :-/O

Thank you Leo for a well designed and useful calibrator. :clap:
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #27 on: March 21, 2018, 11:06:51 pm »
I made a small protective shell for the LB generator and attached the STL file in case some of you want it and can't be bothered designing one. ;)

It clicks together and is held in place by a moderately tight fit between the tiny layer ripples.
It was sliced for and printed on a Prusa I3mk3, so adjustments might be needed if you have a different printer. :-/O
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #28 on: March 22, 2018, 12:48:07 am »
Please post a link in the thread Leo started so other people see it.  While not as elegant, the heatshrink should serve me fine.

BTW I was playing with mine and one of the 60dBm.com reflection bridges.  Vary educational.  I discovered that most of my BNC cables were NG and my DEC thinwire 50 ohm terminators were not as good as cheap Chinese stuff from eBay. Most of the BNC cables came out of an aircraft harness.  Most likely replaced for cause rather than retirement of airplane.

 

Offline HighVoltage

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Re: GW Instek MDO-2000E
« Reply #29 on: March 22, 2018, 08:32:48 am »
I made a small protective shell for the LB generator and attached the STL file in case some of you want it and can't be bothered designing one. ;)

It clicks together and is held in place by a moderately tight fit between the tiny layer ripples.
It was sliced for and printed on a Prusa I3mk3, so adjustments might be needed if you have a different printer. :-/O
Nice!
Could you please save the two shell pieces in separate STL files or even better in two IGS or STEP files.
Thanks
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #30 on: March 22, 2018, 10:38:27 am »
I have included the Design Spark files, but unfortunately Design Spark can't make STEP or IGS files.
The program can be downloaded for free from RS-components if you want to make changes.

If your CAD program support many import formats, you can also rename the .RSDOC files to .ZIP and check if you can find something that is compatible with your system. :-//
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Offline HighVoltage

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Re: GW Instek MDO-2000E
« Reply #31 on: March 23, 2018, 01:41:23 pm »
I have included the Design Spark files, but unfortunately Design Spark can't make STEP or IGS files.
The program can be downloaded for free from RS-components if you want to make changes.

If your CAD program support many import formats, you can also rename the .RSDOC files to .ZIP and check if you can find something that is compatible with your system. :-//
It worked, I figured out a way to use the STL files and make them in to CAD files.
Thanks
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Offline SWR

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Re: GW Instek MDO-2000E
« Reply #32 on: March 23, 2018, 03:11:12 pm »
Cool. 8)
Then you can post a pair of STEP files. :-+
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Offline grizewald

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Re: GW Instek MDO-2000E
« Reply #33 on: January 08, 2020, 04:41:22 pm »
I made a small protective shell for the LB generator and attached the STL file in case some of you want it and can't be bothered designing one. ;)

It clicks together and is held in place by a moderately tight fit between the tiny layer ripples.
It was sliced for and printed on a Prusa I3mk3, so adjustments might be needed if you have a different printer. :-/O

Many thanks for this, it printed perfectly on my printer (custom CoreXY). I made a small modification to the design and added the specs as embossed text so that I could fill them with black marker and gently sand the surface afterwards to remove the overspill from filling the text.



The effect looks better in the flesh than it does in the picture!

I've attached a ZIP of the revised .STL.
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #34 on: January 08, 2020, 05:18:46 pm »
I want three!  1 MHz, 10 MHz and 100 ps pulse.  Unfortunately, I don't have a 3D printer.  If someone reading this can print 3 of these for me I'd be very grateful with payment by PayPal. Or direct me to someplace that will print them to order.

It would be *really* nice if Leo offered these.  I've got heatshrink on mine, but the case would be much better.

Reg
 

Offline grizewald

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Re: GW Instek MDO-2000E
« Reply #35 on: January 10, 2020, 07:30:31 pm »
I want three!  1 MHz, 10 MHz and 100 ps pulse.  Unfortunately, I don't have a 3D printer.  If someone reading this can print 3 of these for me I'd be very grateful with payment by PayPal. Or direct me to someplace that will print them to order.

It would be *really* nice if Leo offered these.  I've got heatshrink on mine, but the case would be much better.

Reg

I'd be happy to print three for you if you want at no cost other than the postage, you could even have three different colours. Then again, if you get hit for import charges, it might turn out to be a stupidly expensive way to get three plastic cases printed, what with you being in the USA and me being in Sweden!

I used Tinkercad (free, web based) to add the lettering to SWR's original .STL files. You should be able to find someone local to you via 3dhubs or you could get Shapeways to print some for you.

Alternatively, you can get perfectly acceptable prints from a $200 Creality 3D printer and once you start, you'll discover no end of useful housings, jigs and accessories that you'll never know how you lived without. :)
  Lord of Sealand
 
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Offline rhb

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Re: GW Instek MDO-2000E
« Reply #36 on: January 11, 2020, 12:51:40 am »
My mother grew up in Stockholm before coming the the US with the Swedish diplomatic service in 1944, so it might be worth any tariff (unlikely) just to say they came from Sweden.  "Made in Sweden" is a big deal to me and my two sisters.  I never had the opportunity to stay in Sweden long enough to  learn Swedish, but both my sisters did.  However, I think you are correct, I should buy a small 3D printer.

I didn't realize that 3D printers had become cheap and good enough to be worth having.  The Monoprice Mini Delta looks as if it would serve my needs very well.  I have a well equipped 150 sq m shop with a full range of tools and tooling for wood and metal.

The Creality reviews I read indicated that they have some issues with ABS in the cheaper models and bed leveling is a hassle.  While they offer greater build volume, I don't expect to be making large prints.  Small custom enclosures or brackets are my most likely build.  And the print times are so long that even if I got a bigger printer, I'd keep the Mini Delta for small prints.

Thanks a lot.

Have Fun!
Reg
 

Offline grizewald

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Re: GW Instek MDO-2000E
« Reply #37 on: January 11, 2020, 12:25:20 pm »
My mother grew up in Stockholm before coming the the US with the Swedish diplomatic service in 1944, so it might be worth any tariff (unlikely) just to say they came from Sweden.  "Made in Sweden" is a big deal to me and my two sisters.  I never had the opportunity to stay in Sweden long enough to  learn Swedish, but both my sisters did.  However, I think you are correct, I should buy a small 3D printer.

I didn't realize that 3D printers had become cheap and good enough to be worth having.  The Monoprice Mini Delta looks as if it would serve my needs very well.  I have a well equipped 150 sq m shop with a full range of tools and tooling for wood and metal.

The Creality reviews I read indicated that they have some issues with ABS in the cheaper models and bed leveling is a hassle.  While they offer greater build volume, I don't expect to be making large prints.  Small custom enclosures or brackets are my most likely build.  And the print times are so long that even if I got a bigger printer, I'd keep the Mini Delta for small prints.

Thanks a lot.

Have Fun!
Reg

In addition to what I said in reply to your PM, I'd steer clear of a cheap delta as they're often more trouble than they are worth. I'd also steer clear of ABS. It's an absolute bugger to print, often requires a heated enclosure to prevent warping and emits foul smelling and toxic fumes while you are printing with it. There are far better plastics available - PLA for things which don't need to withstand more than 50°C during use and PET-G for up to 80°C. Neither of these two emit toxic fumes and neither is particularly difficult to print.

Bed levelling can be a hassle on many printers, particularly so when the designers insist in repeating the mistake of having four connections between the bed and its support. Levelling a plane by adjusting four corner points is nearly impossible. The correct way to do it is with three points in a triangle (which as I'm sure you know, is all you need to mathematically define a plane). First you adjust one of the three points to be your reference and then you use the other two points to adjust pitch and roll.

Given that the actual print surface on most printers isn't perfectly flat to start with, the best solution is to get the print surface as level as possible mechanically and then use a sensor to create a map of the actual bed surface at many points and use interpolation when printing to translate the grid of probe points into the correction needed at any point on the print surface.
  Lord of Sealand
 

Offline rhb

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Re: GW Instek MDO-2000E
« Reply #38 on: January 11, 2020, 05:03:01 pm »
I have always considered the delta design a cost compromise.   After your post I spent several hours looking at prices and reviews startng with the cheaper Creality models, some of which compared them to the Monoprice models..  The Monoprice Mini Delta got very high marks from several reviewers.  The small size and speed were a significant plus for my intended uses.  So I bought one on Amazon and a roll of black PLA.

I've been following 3D printing for a long time, but generally unimpressed.  However, I also have extensive knowledge of manufacturing processes of all types.  I'm much more interested in hydraulic (aka rubber) forming of aluminum sheet,  injection molding plastics and casting aluminum.  But for under $200 if it will make usable brackets and boxes that will justify it.

My sister does a *lot* of miniature stuff.  I suspect she will use it more than I.  However, if I start using it for making molds for investment casting or  injection molding plastic that might change.

In general I view 3D printing as a solution for one offs, prototypes and tooling.  Spending several hours of machine time to make a single item isn't really satisfactory if you need a couple dozen of something.  So I've always been amused by the idea of 3D printers for manufacturing.

Have Fun!
Reg

 

Online nctnico

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Re: GW Instek MDO-2000E
« Reply #39 on: January 11, 2020, 05:41:33 pm »
In general I view 3D printing as a solution for one offs, prototypes and tooling.  Spending several hours of machine time to make a single item isn't really satisfactory if you need a couple dozen of something.  So I've always been amused by the idea of 3D printers for manufacturing.
You can use 3D printers for small batches but getting at that point requires a lot of effort and good 3D printers. The casings for my HF differential probe are 3D printed and they seem to have a nice repeatability. I have outsourced design & printing to an external company though and they went through a couple of test prints to see what works best.

I have always been amused by the idea that you can buy a $200 printer and expect it to print perfect plastic parts right out of the box. From what I've read it won't and even 3D printers which cost 10 times more can be outright finicky.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline grizewald

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Re: GW Instek MDO-2000E
« Reply #40 on: January 11, 2020, 09:53:19 pm »
It's true that all 3D printers can be fickle beasts. My main printer is a CoreXY design which I've built from aluminium extrusions. It's built like a tank and has the best control systems and parts that I can afford. Most of the time, it makes great prints. However, I can't control the climate and consistently get worse results in the winter from all my printers.

However, I don't think it's fair to sweep all the cheap Chinese printers into the same hat. Many of Creality's 1st generation printers are "nice try, but no cigar", but the revised versions where they have added things like levelling probes are actually superb value for money.

The also have the huge advantage of only needing two main assemblies bolting together and they're ready to go. My big printer took me a long time to build properly and even longer to tune it and get to know the unique characteristics which it has.

The main limitation of FDM printing is speed. There are fundamental limits on how quickly you can lay down a string of molten plastic with +/- 10 micron or better accuracy. Then again, speed is only a perceptual issue. If you did want to mass produce parts with an FDM printer, all you have to do is add more machines! Just look at Prusa printers - they now have 500 of their own printers in their printer farm pumping out parts for new printers 24/7.
For the hobbyist, the only problem caused by FDM printing speed is one of impatience. As my printer is close to silent in operation, if a print takes 72 hours then fine! It's not as if it keeps me awake at night and power cuts are very rare.

 
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Offline grizewald

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Re: GW Instek MDO-2000E
« Reply #41 on: January 11, 2020, 09:56:10 pm »

My sister does a *lot* of miniature stuff.  I suspect she will use it more than I.  However, if I start using it for making molds for investment casting or  injection molding plastic that might change.


She won't be using an FDM printer for miniatures, the resolution is simply too low. An SLA printer on the other hand is the miniature maker's dream and these days, similarly priced compared to a good FDM printer.
  Lord of Sealand
 


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