On 28/10/2018 13:35, Tom Gardner wrote:> On 28/10/18 13:24, Rob wrote: >> Tom Gardner <spamjunk@blueyonder.co.uk> wrote: >>> I believe it is because there has been a change in the loads >>> on the grid. Nowadays there are a large number of devices >>> with SMPSs. Many presume a more-or-less constant input voltage >>> throughout the mains cycle, so they rectify the and smooth the >>> mains, "topping up" the charge in the capacitor only at the >>> peak voltages. Hence significantly more current is drawn at >>> the peaks than at other parts of the cycle. >> >> More modern SMPSs should fix that by having PFC (Power Factor >> Correction). >> >> It basically is an extra switching boost-converter in front of the main >> capacitor operating from unsmoothed rectified mains, it converts the >> half-sinewave voltage to a constant voltage to charge the capacitor. >> (the working point of the converter is changing all the time in the >> rhythm of the mains voltage) >> >> Of course there still exists a lot of equipment without this, now >> manadatory, feature. And it is not required for lowpower devices, >> which become more and more prevalent. > > What's not clear to me is whether the large number > of "low power" PSUs in domestic equipment is sufficient > to clip the peaks. > > I'm open to other suggestions, of course. >Not just SMPS, many mains transformers and motors go into soft saturation near peaks. But in general I think it is more to do with the large number of appliances within a few tens of metres of you - the waveform on the HV grid pylons might be much purer? piglet
amazing ARB pricing
Started by ●October 25, 2018
Reply by ●October 28, 20182018-10-28
Reply by ●October 28, 20182018-10-28
Tom Del Rosso wrote:>>> Just how arbitrary is an ARB? Can any of them download a waveform >>> from a scope and make little adjustments like reducing overshoot or >>> ringing, so you can see if doing so would help before you go to the >>> effort of reducing it for real? >>> >>> Or do they just do complex modulations, or is it just another name >>> for function generator? >> >> Some may be able to download directly from a scope but it would >> probably have to be the same brand. They usually have front panel >> waveform creation and editing where you can step through a waveform >> point by point and either directly enter a numerical value or use the >> up and down arrows to modify it. All should be able to talk to a PC, >> and the scope should also be able to talk to the PC so you should be >> able to upload a waveform with the scope software, either save it >> directly or export as a CSV file depending on the brands, then import >> into the ARB software, edit as desired, and then download. The >> waveform is point-by-point completely arbitrary but then you have to >> take into account the sample rate and bandwidth of the ARB to >> determine just how sharp a corner you can actually get and also what >> the actual output frequencies will be (if the scope and ARB sampling >> rates differ, for example). They are great fun to play with, and >> actually useful too :-). One gotcha for me with the cheap ARBs in >> this thread is that the longest a single waveform can be is only 8192 >> points. I assume that you can slow down the sample rate to extend >> that in time but eventually you hit the minimum required bandwidth. They >> can store 64 waveforms and might be able to chain waveforms >> together with no glitches or timing issues which would allow one 512 >> Kpt waveform but you would have to handle the breaking apart and >> downloading in software. I haven't read the manual to see if all >> that would work. > >Thanks, I suspected as much. There's still lots of room for improvement in >the software to cut the number of steps. > >I assume the memories are so small because they used a small FPGA with not >enough address lines. That's another place where they could improve it a >lot for a few dollars.Just browsing casually, in the 10-60 MHz range, going from $100ish to $350ish seems to get you from 8 bits to 12, 14, or 16 bits, and from 8 KPts to 1+ Mpts per waveform. www.saelig.com has a good selection of test gear so it's easy to compare features there (I'm a satisfied customer, YMMV), but there are more and more places to buy so price shop to your heart's content. -- Regards, Carl Ijames
Reply by ●October 28, 20182018-10-28
On Sat, 27 Oct 2018 02:33:15 -0700 (PDT), speff <spehro@gmail.com> wrote:>On Saturday, 27 October 2018 04:36:58 UTC-4, Tom Gardner wrote: >> On 27/10/18 04:32, Johnny B Good wrote: >> > On Fri, 26 Oct 2018 13:27:07 -0700, Klaus Kragelund wrote: >> > >> >> A 200MHz scope for 379 USD: >> >> >> > >> > I've been considering replacing my ancient 1950s CRT dual beam 70Lbs >> > 'scope with something more up to date recently and this Siglent >> > Technologies SDS1202X-E 'scope looked like it might be a good value >> > proposition (a snip at a mere �363.05 for UK customers via Amazon's >> > 'Fulfilment' delivery) so have checked out some reviews[1] which seem to >> > confirm this view. >> > >> > However, this is a subject of very recent interest so I haven't yet >> > researched this in any great depth as yet so I was wondering if you had >> > any advice on this 'scope or possibly better alternatives (100MHz B/W >> > dual trace at a minimum) that you could offer to aid me in my search for >> > a reasonably specced and priced unit? >> >> This topic comes up once per week on EEVBlog forum, and is discussed >> ad nauseam there. Many of the responses are "just buy X it is >> the best available now", but a few are more measured. >> >> There are also some long /long/ threads on reviews of the popular >> bottom-end scopes. >> >> Read EEVBlog forum and you will have a better idea of what >> questions you should ask, and some answers for them. >> >> Don't throw the boat anchor away until you are satisfied >> that the new scope can do everything you want at least as >> well as the boat anchor. > >My Tek battery powered digital scope lies to you if you set the >sweep too slow for the signals.. there does not appear to be any >anti-aliasing filter. Analog scopes don't lie in that particular >disturbing manner. > >--spThe analog scope will just show a solid rectangle of light when the sweep is too slow for the waveform. I think a digital scope could do that, with a bit of code, instead of aliasing. It could also intensity weight on duty cycle, like an analog scope does. One quickly learns to recognize the aliasing and crank up the sweep rate. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●October 28, 20182018-10-28
On 10/28/18 12:40 PM, John Larkin wrote:> On Sat, 27 Oct 2018 02:33:15 -0700 (PDT), speff <spehro@gmail.com> > wrote: > >> On Saturday, 27 October 2018 04:36:58 UTC-4, Tom Gardner wrote: >>> On 27/10/18 04:32, Johnny B Good wrote: >>>> On Fri, 26 Oct 2018 13:27:07 -0700, Klaus Kragelund wrote: >>>> >>>>> A 200MHz scope for 379 USD: >>>>> >>>> >>>> I've been considering replacing my ancient 1950s CRT dual beam 70Lbs >>>> 'scope with something more up to date recently and this Siglent >>>> Technologies SDS1202X-E 'scope looked like it might be a good value >>>> proposition (a snip at a mere £363.05 for UK customers via Amazon's >>>> 'Fulfilment' delivery) so have checked out some reviews[1] which seem to >>>> confirm this view. >>>> >>>> However, this is a subject of very recent interest so I haven't yet >>>> researched this in any great depth as yet so I was wondering if you had >>>> any advice on this 'scope or possibly better alternatives (100MHz B/W >>>> dual trace at a minimum) that you could offer to aid me in my search for >>>> a reasonably specced and priced unit? >>> >>> This topic comes up once per week on EEVBlog forum, and is discussed >>> ad nauseam there. Many of the responses are "just buy X it is >>> the best available now", but a few are more measured. >>> >>> There are also some long /long/ threads on reviews of the popular >>> bottom-end scopes. >>> >>> Read EEVBlog forum and you will have a better idea of what >>> questions you should ask, and some answers for them. >>> >>> Don't throw the boat anchor away until you are satisfied >>> that the new scope can do everything you want at least as >>> well as the boat anchor. >> >> My Tek battery powered digital scope lies to you if you set the >> sweep too slow for the signals.. there does not appear to be any >> anti-aliasing filter. Analog scopes don't lie in that particular >> disturbing manner. >> >> --sp > > The analog scope will just show a solid rectangle of light when the > sweep is too slow for the waveform. I think a digital scope could do > that, with a bit of code, instead of aliasing. It could also intensity > weight on duty cycle, like an analog scope does.Lots of them do that now. It's a nice feature.> > One quickly learns to recognize the aliasing and crank up the sweep > rate.You can also just live in 'envelope' mode. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●October 28, 20182018-10-28
On Sunday, 28 October 2018 17:57:25 UTC, Phil Hobbs wrote:> On 10/28/18 12:40 PM, John Larkin wrote: > > On Sat, 27 Oct 2018 02:33:15 -0700 (PDT), speff <spehro@gmail.com> > > wrote: > > > >> On Saturday, 27 October 2018 04:36:58 UTC-4, Tom Gardner wrote: > >>> On 27/10/18 04:32, Johnny B Good wrote: > >>>> On Fri, 26 Oct 2018 13:27:07 -0700, Klaus Kragelund wrote: > >>>> > >>>>> A 200MHz scope for 379 USD: > >>>>> > >>>> > >>>> I've been considering replacing my ancient 1950s CRT dual beam 70Lbs > >>>> 'scope with something more up to date recently and this Siglent > >>>> Technologies SDS1202X-E 'scope looked like it might be a good value > >>>> proposition (a snip at a mere £363.05 for UK customers via Amazon's > >>>> 'Fulfilment' delivery) so have checked out some reviews[1] which seem to > >>>> confirm this view. > >>>> > >>>> However, this is a subject of very recent interest so I haven't yet > >>>> researched this in any great depth as yet so I was wondering if you had > >>>> any advice on this 'scope or possibly better alternatives (100MHz B/W > >>>> dual trace at a minimum) that you could offer to aid me in my search for > >>>> a reasonably specced and priced unit? > >>> > >>> This topic comes up once per week on EEVBlog forum, and is discussed > >>> ad nauseam there. Many of the responses are "just buy X it is > >>> the best available now", but a few are more measured. > >>> > >>> There are also some long /long/ threads on reviews of the popular > >>> bottom-end scopes. > >>> > >>> Read EEVBlog forum and you will have a better idea of what > >>> questions you should ask, and some answers for them. > >>> > >>> Don't throw the boat anchor away until you are satisfied > >>> that the new scope can do everything you want at least as > >>> well as the boat anchor. > >> > >> My Tek battery powered digital scope lies to you if you set the > >> sweep too slow for the signals.. there does not appear to be any > >> anti-aliasing filter. Analog scopes don't lie in that particular > >> disturbing manner. > >> > >> --sp > > > > The analog scope will just show a solid rectangle of light when the > > sweep is too slow for the waveform. I think a digital scope could do > > that, with a bit of code, instead of aliasing. It could also intensity > > weight on duty cycle, like an analog scope does. > > Lots of them do that now. It's a nice feature. > > > > One quickly learns to recognize the aliasing and crank up the sweep > > rate. > > You can also just live in 'envelope' mode. > > Cheers > > Phil Hobbsit's a somewhat effective way to get a scope to see signals above its frequency limit, doing the enveloping externally. NT
Reply by ●October 28, 20182018-10-28
On 10/28/18 3:00 PM, tabbypurr@gmail.com wrote:> On Sunday, 28 October 2018 17:57:25 UTC, Phil Hobbs wrote: >> On 10/28/18 12:40 PM, John Larkin wrote: >>> On Sat, 27 Oct 2018 02:33:15 -0700 (PDT), speff <spehro@gmail.com> >>> wrote: >>> >>>> On Saturday, 27 October 2018 04:36:58 UTC-4, Tom Gardner wrote: >>>>> On 27/10/18 04:32, Johnny B Good wrote: >>>>>> On Fri, 26 Oct 2018 13:27:07 -0700, Klaus Kragelund wrote: >>>>>> >>>>>>> A 200MHz scope for 379 USD: >>>>>>> >>>>>> >>>>>> I've been considering replacing my ancient 1950s CRT dual beam 70Lbs >>>>>> 'scope with something more up to date recently and this Siglent >>>>>> Technologies SDS1202X-E 'scope looked like it might be a good value >>>>>> proposition (a snip at a mere £363.05 for UK customers via Amazon's >>>>>> 'Fulfilment' delivery) so have checked out some reviews[1] which seem to >>>>>> confirm this view. >>>>>> >>>>>> However, this is a subject of very recent interest so I haven't yet >>>>>> researched this in any great depth as yet so I was wondering if you had >>>>>> any advice on this 'scope or possibly better alternatives (100MHz B/W >>>>>> dual trace at a minimum) that you could offer to aid me in my search for >>>>>> a reasonably specced and priced unit? >>>>> >>>>> This topic comes up once per week on EEVBlog forum, and is discussed >>>>> ad nauseam there. Many of the responses are "just buy X it is >>>>> the best available now", but a few are more measured. >>>>> >>>>> There are also some long /long/ threads on reviews of the popular >>>>> bottom-end scopes. >>>>> >>>>> Read EEVBlog forum and you will have a better idea of what >>>>> questions you should ask, and some answers for them. >>>>> >>>>> Don't throw the boat anchor away until you are satisfied >>>>> that the new scope can do everything you want at least as >>>>> well as the boat anchor. >>>> >>>> My Tek battery powered digital scope lies to you if you set the >>>> sweep too slow for the signals.. there does not appear to be any >>>> anti-aliasing filter. Analog scopes don't lie in that particular >>>> disturbing manner. >>>> >>>> --sp >>> >>> The analog scope will just show a solid rectangle of light when the >>> sweep is too slow for the waveform. I think a digital scope could do >>> that, with a bit of code, instead of aliasing. It could also intensity >>> weight on duty cycle, like an analog scope does. >> >> Lots of them do that now. It's a nice feature. >>> >>> One quickly learns to recognize the aliasing and crank up the sweep >>> rate. >> >> You can also just live in 'envelope' mode. >> >> Cheers >> >> Phil Hobbs > > it's a somewhat effective way to get a scope to see signals above its frequency limit, doing the enveloping externally. > > > NT >I prefer to just buy a faster scope. Why waste a nice excuse like that? ;) I have scopes with bandwidths of 50 GHz (11801C), 20 GHz (11802), 3 GHz (TDS 694C), two at 1 GHz (TDS 784A), and a number of slower ones. Fast boat anchors are pretty cheap. I would like one with serial decode eventually, but I rarely need that sort of thing. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●October 28, 20182018-10-28
On 2018-10-28 02:44, Martin Brown wrote:> On 27/10/2018 23:36, John Larkin wrote: >> On Sat, 27 Oct 2018 14:50:08 -0700, Joerg <news@analogconsultants.com> >> wrote: >> >>> On 2018-10-25 14:27, John Larkin wrote: >>>> >>>> >>>> https://www.amazon.com/Adoner-Precision-Arbitrary-819214bits-Modulation/dp/B07BF7Y7TJ/ref=sr_1_3?ie=UTF8&qid=1540502597&sr=8-3&keywords=fy6600&dpID=41vbYI%252B7YiL&preST=_SX342_QL70_&dpSrc=srch >>>> >>>> >>>> Other places have this box for $99. >>> >>> I have a no-name ARB because I needed one year ago for aerospace >>> testing. The 1st one had a bum FPGA. Was replaced. The 2nd one now has a >>> slowly failing rotary encoder. Oh well. >> >> Even if they are junk, I can't understand how or why they would sell >> all that for $99. > > Presumably because they can make them in bulk for less than $80 and are > content with a rather small margin on each sale. I am tempted to get one > but so far I have resisted. Sooner or later I will find an excuse to > buy one and clutter up my equipment rack some more. I presume the model > of choice is the 14bit DAC version but which of the many "brands" of > identical spec kit is the original design or are they all made in one > factory and badged by the resellers (much like some LCD TVs). >Likely much less than $80. Even back in the early 90's we had Asian pricing and rest of world (ROW) pricing. I learned that very quickly when working in South Korea for the first time. Internet was in its infancy so they had wallpapered a whole hallway with daily updated computer printouts (remember the "tractor paper"?) and there was a constant pilgrimage to that wll by design engineers. It's amazing how low you can go if a transistor costs around one cent. They also did not have the hugely expensive placement cost penalty that many Western enterprises had to or sometimes still have to deal with. What blew my mind was when in the mid-90's (!) someone showed the fully burdened cost of a simple fax machine, from scratch to packaged product with manual and all. That cost total was slightly under $7. Profitably making and selling an ARB generator for around $100 is a piece of cake for Asians. Especially since the R&D costs are often, ahem, negligible. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 28, 20182018-10-28
On Saturday, October 27, 2018 at 4:04:13 AM UTC-4, speff wrote:> On Friday, 26 October 2018 20:53:56 UTC-4, tabb...@gmail.com wrote: > > On Friday, 26 October 2018 23:26:30 UTC+1, speff wrote: > > > On Friday, 26 October 2018 14:05:08 UTC-4, Carl wrote: > > > > > > grounding. It's on eBay for $110-120 depending on frequency range (20, 30, > > > > 40, 60 MHz) so basically the same price. Interestingly, each frequency step > > > > only adds about $2-3 to the price so I don't see why anyone wouldn't just > > > > get the 60 MHz model. > > > > > China domestic retail pricing is almost exactly double for the 60MHz compared to 20MHz. That's for the original unit from the factory. Some (maybe most) of the eBay ones appear to be clones. I wonder if they cheaped out on the DAC. > > > > > > you don't think they cheaped out on every bit? > > > > > > NT > > The original manufacturer, probably not. They say they've sold more than 100K pieces. > > ------ > Listen to the advice of the majority of users, and strive to provide customers with friends with more convenient and easy to use high-performance, cost-effective products. > > Product upgrade! > > 1. Add AM, FM, PM, ASK, FSK, PSK modulation functions! > > 2. The phase adjustment resolution is upgraded to 0.01°; > > 3. The duty cycle adjustment resolution is upgraded to 0.01%; > > > 4. The square wave rising edge and falling edge time are adjustable. When the instrument sets the square wave output, press the F4 button to switch between the duty cycle and the lifting edge time setting, thus making the instrument more applicable!One of my sig gens' does square waves with adjustable edges, that can useful. GH> > 5, the use of silicone buttons and gold-plated button contacts, so that the instrument button life is longer, the operating feel is more comfortable.
Reply by ●October 28, 20182018-10-28
On Sat, 27 Oct 2018 02:33:15 -0700, speff wrote:> My Tek battery powered digital scope lies to you if you set the sweep > too slow for the signals.. there does not appear to be any anti-aliasing > filter. Analog scopes don't lie in that particular disturbing manner. >Speff! Good to see you back again! And making great sense, too. We need more of that here nowadays. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.
Reply by ●October 28, 20182018-10-28
On Sunday, October 28, 2018 at 8:53:40 AM UTC-4, Jeroen Belleman wrote:> On 27/10/18 03:23, George Herold wrote: > > On Friday, October 26, 2018 at 4:27:11 PM UTC-4, Klaus Kragelund wrote: > >> A 200MHz scope for 379 USD: > >> > >> https://www.amazon.com/Siglent-Technologies-SDS1202X-Oscilloscope-Channels/dp/B06XZML6RD/ref=pd_aw_sbs_328_of_13?_encoding=UTF8&pd_rd_i=B06XZML6RD&pd_rd_r=0578ee0f-d95c-11e8-8a27-e7c97784a407&pd_rd_w=dV3r6&pd_rd_wg=B2YIF&pf_rd_i=mobile-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=926ebe02-3236-40c6-ac63-01ad178f498a&pf_rd_r=Y2SMMGCRT1ZGCYBYF1GE&pf_rd_s=mobile-dp-sims&pf_rd_t=40701&psc=1&refRID=7M8XSZS3XF3JSQZ68R27 > >> > >> Cheers > >> > >> Klaus > > > > I'm totally in love with this keysight 'scope, but I think it's > > close to ~$1k.. it just does everything right. > > (and it all starts with the triggering.) > > > > I turn it on and it remembers all the last settings, > > all stuff should do that. > > > > George H. > > > > All stuff *used to* do that. Welcome to the new age. > > Jeroen BellemanI've mostly been using cheaper stuff, that doesn't have that feature. You turn it off and it forgets, and goes back to defaults. Have you tried one of the new keysight 'scopes? I have yet to find something to complain about.. and mostly I'm just amazed. I was doing single screen captures bang... there's the event I'm looking for, now I need to see how it ends, I turn the time base knob.. and low and behold the rest of the signal is there! George H.
