Matching your equipment and setting up for your expected goals - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: April 19, 2025, 06:02:59 pm
content: In a thread on Test Equipment, I asked about the precision of the Siglent SDG2122X AWG. I decided to upgrade to it before the tarrifs kicked in. Long story short, my observed "inaccuracies" were actually due to my expectation that the SDS824X could precisely reproduce a 10.7MHz sinewave generated from that AWG. You can read that thread for the details.The reason the scope was reporting variations in freq was not due to the AWF, but due to the design tolerances of the scope. If I wanted the level of precision I naively expected, I would need to spend orders of magnitude more money. That is why professional scopes can cost a $100K.OOPS!But it got me thinking. The SDG1062 x is sufficient for and exceeds that scope. I am not going to now buy a scope that matches the SDG2122x. I am simply do not expect to work at that level in my projected timeframe.This also leads me to suspect I do notneedthe SDS824. Half the reason for buying it is the capability to analyze digital signals. Digital electronics is not one of my goals. If it weren't for the math functions and potential of the Bode plots, I might be better off with a dual timebase analog scope. I am not going to give it up, but I may find space for my BK 1570A.In the meantime, I am still in the first year EE course in my studies. And I do have (and use) the Analog Discovery AD3. For my labs and breadboarding, this is entirely satisfactory.My point is, that non pros should carefully consider the level of precision they actually need in their labs. Most of us do not need 5 digit DMMS, let alone 6.5 digit ones. Alan on W2aew does a lot with a Simpson 260!Aldo keeps coming up with interesting alternatives. And if you have a decent meter, do you really need a PSU withcalibrated output meters? All of these add to costs.It is only if you get into repair/restoration that you need anything more than AD3 and some of the low level voltage stuff that Aldo champions. Especially if you are working with things like Arduino.I do have the sickness that makes high quality (read ex pro) equipment attractive. And bottom feeding is my hobby. But in recent months, I have been off loading some of that because it was really driven by ego, not rational requirements.In my experience, the best and most useful things I have purchased are:The AD3A couple DMMs (Fluke 45, Fluke77/FM) and Simpson 360s for concurrent measurementsAn ERSA soldering stationBOOKS!!!!Multisim (look on Internet Archive)TINA for StudentsOn the border about the scopes. Maybe should have stuck with the BK 20MHz Freq generator.ASP Breadboards (and yes I have been schooled on parasitics)An older Instek GPS4303Shannon TweezersYeah, the HK Curve tracerAO580 scope for SMD work (actually from my watch shop)Bench lamp with GLASS 3 x magnifierStorage BoxesYihua Heat Gun (shrink tube and drying cleaner off boards)On the fence about the Hakko FR301; very demanding of attentionI do have a Labvolt variable 120VAC/12VDC supply and a Tenma Isolation Transformer; They are used very rarely; but each cost under $50 so I can justify themWhile I have them from my business:A good set of screwdrivers with bits for all fastenersTweezers (I use bronze for much work but the ESD safe ones when indicated)Good EuropeanBoxjoint pliers and cutters. Vintage is great stuff!Stuff I shouldnothave bought:Bargain "Grabbers"Riden RD6012P PSU (do not use, do not like the interface, do not need programable)Generic Breadboards (Non ASP)Breadboard wire (use ribbon cable wire with connectors installed)A BK 415 Sweep/Marker generatorScopes that are not mainstream (like Kikusui)Ali Soldering Practice KitsTI Engineering Calculators (There is a great phone app that does it all, and makes your phone look like a calculator)Maybe the Retro Chip IC tester?? I enjoyed building it and have a bunch of Logic ICs, but not sure I will ever use the ICs.I am sure there are others, but I must have forced them out of my memory.I bought resistors and caps (TH and SMD) from Ali; but I buy current actives only from the accepted places. I did buy stockroom bags of caps (including ECs) but I built a 400VDC leakage tester to check them before I use them. I also bought a bag lot of transistors and assembled almost a complete run of ECG boxed and bagged components cheaply before ECG closed. (hence the HK Curve Tracer). I like the rational inventory.(30 years ago I bought mixed assortments of watch/clock pinions and spent evenings sorting them by size and leaf count. Still living off them and others want to be first in line when Mary sells my stuff. Same with mainsprings and jewels, now getting hopelessly expensive).As you progress, you can upgrade as needed. And prices will only come down while the technology increases. Do not bother trying to future proof yourself by buying over what you project doing for the next 5 years.Just my personal cautionary tale and I hope others with other points of view jump in.

author: 2N3055
author_rank: Super Contributor
timestamp: April 19, 2025, 08:08:49 pm
content: Quote from: watchmaker on April 19, 2025, 06:02:59 pmIt is not about "design tolerances of the scope in question"!!It is about how scopes in general measure this, and not understanding that 3-5 ps uncertainty (which is mind-bogglingly high accuracy 0,000000000003s. 3 trillionth the second) is still what looks like large error in frequency on top of 10MHz but is 40ppm error.In attachment from MSOX3104T that was 15000USD scope when new.Together with your scope measuring same thing but with help of little math. This averaging method will work on Keysight too to get better results.What do we conclude? Scope is not an instrument for this measurement if you want parts per billion accuracy. And nobody will claim it is.OTOH a measurement technique and good understanding how things work will yield better than order of magnitude better results.And some 500USD scopes will do as well as 15000USD scopes.Same thing applies to any instrument and measurement.Best,

author: watchmaker
author_rank: Unknown
timestamp: April 20, 2025, 01:25:49 am
content: Trust me, I am not dissing Siglent stuff. I think the line represents a remarkable level of technology, reliability and value for money. I was remarking on my naivete.My point here is that it is easy to get distracted by shiny objects; which I admit to.While I have the wherewithal to indulge, the conversation we had on TE got me to thinking a bit more rationally. Maybe I will use all the features of AWG; but perhaps the BK 20MHz would have met my "real" needs/goals? Do I need more than the AD3? (although I do enjoy troubleshooting as a problem solving exercise which means more powerful tools).And I pointed out specifically that the SDS824 has functions that are well worth having and unimaginable when I was a shop student using a DuMont. And it is very well featured for those working in digital. But those features are lost on me.Hence the sharing of my observations as an adult learner with a little over a year of experience in this area. To be honest, I think I acted a bit like someone who declares he wants to be a watchmaker and buys all the toys without understanding them. New and shiny objects.Problem is, as pointed out in the TE thread, there are techniques and approaches that are freely shared in a professional setting and in vendor seminars that, while there are people here who are very generous, those settings cannot be reproduced in this forum or even on YouTube. And for people like me, who do not work with scope every day, I constantly find myself forgetting where I filed the hints and practices that resolved my issue the last time.It is like one off lathe work. The best way to learn is with an experienced hand and doing it every day.I am hopeful others can benefit from my experience and what people like you have to say on the subject.

author: 2N3055
author_rank: Super Contributor
timestamp: April 20, 2025, 08:35:22 am
content: I am sorry if it came out as I meant you are bad-mouthing something.It was not my intention. I just wanted to enhance your message with my "tool for the job" mantra.Many times we are encountering users that are on the learning curve that bought some tool and are now confused about details.And many times we have questions that are basically equivalent to "I wanted to buy better tools than my old dollar store ones. And now I am disappointed because my new, expensive, PB Swiss screwdriver is no better at driving nails than the cheap old one...".As for reproducing results, that is all about learning. I explained in detail how things need to to be set to get good result. Also explained why. Additional questions are welcome.

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2025, 09:12:15 am
content: Quote from: watchmaker on April 20, 2025, 01:25:49 amWe are all enticed by shiny new geegaws, and it is good to recognise it.Nonetheless, engineers and scientists do well to be guided by Occam's Razor, and - for many reasons - pare things down to the minimal essential. "An engineer is someone who can do something for $1 that anybody can do for $10".Plus, there is a satisfaction to be gained from using insight and understanding. See the aphorism in my .sig.