EEVblog #983 - A Shocking Oscilloscope Problem!

hi I was going to work this as a quick video on my second channel like I just uploaded two videos on Eevee blog too with two little bugs I found in the new road and Schwartz RTB to double for oscilloscope like five minutes after a couple of minutes after I started using it and I found another issue here is about to start like a first impressions review I just discovered this I thought it was worth showing you this and sort of i comparing it against different scopes we're talking about micro phonics in particular micro phonics in multi-layer ceramic capacitors now I've mentioned this on videos before on Maury on ceramic capacitors capacitors and things like that I've even shown you that how that the humble oscilloscope probe can also be microphonic if you tap it on the bench because well this end in here is going to have a multi-layer ceramic capacitors in it so when you tap it they can actually be microphonic generate a voltage inside the capacitor and it can cause a problem in all sorts of not just the oscilloscope probes but all sorts of products all sorts of systems real trap beyond players something to watch out for and you'll notice that this will change a bit depending on the surface I've got obviously if I tap it on the bench here that's a hard surface that's generating a lot of G into the actual probe itself now if I put it onto the anti-static mat over here which is sponger it's a similar kind of response it's slightly it's a say frequency response but the response is a little bit dampened now one of the keys to this is the orientation the physical rotation orientation of the probe when it actually strikes the surface like this that's the position that generates the most amount now if I just rotate it so that the switch is on the top there so I've rotated 90 degrees still does it we get a different response and it is Danton so I actually discovered this on this our TBR - mm and I guess it's not surprising that it's possible but I was a bit shocked at the extent of it inside this thing now what I've got set up I've got all my channels set to 2 millivolts per division here I've got it set to two milliseconds per division I've just chosen these as a reasonable example of what we're going to see here the triggering mode I've said to normal is just Ed's trigger triggered off channel 1 rising slope DC coupling no high frequency reject or anything like that it's a very typical low level triggering configuration and with a mid range art time base now take a look at this ok I'm going to work it in single mode and Wow look at that microphonic I'm just using my little plastic thing here that was not a particularly hard tap either that was a just a pretty cure that one didn't do it there's a level there's a level there that it's actually jogged that's where form actually that's because of my my trigger levels actually there sorry so if we set the trigger level just above the noise there ah Jay look it's the tiniest little knot oh that was so gentle and knock that was ah I barely even tapped it and there we go as triggering channel one seems to be worse than the others channel 1 and channel 4 seemed to be like the worst culprits channel 2 seems to be pretty good now I can experiment with this I haven't actually done this yet but ah tap the tap the probe front end like that on channel 1 just gentle tap on channel 2 look at channel 2 it's coupled straight through the B and C the vibration from tapping this couple straight through the B and C onto the PCB onto the front end multi-layer ceramic capacitors if you've no doubt seen my tear downs of analog front ends of oscilloscopes they're filled with multi-layer ceramic capacitors and if you get you know if you're not careful you can get ones that are you know much more micro microphonic than others you've got to be careful you wants a real multi-layer 10 microfarad 10 volt ones or something like that they have a horrible dielectric there they can be really horribly microphonic with all those you know hundreds of layers or dozens or however many layers they have inside there so there are piezoelectric and it's a piezoelectric effect anyway I won't go into details but that wood is almost certainly that what's at fault here because see this is horribly to me that is horribly microphonic I originally found this because I was actually yeah also I think I was tapping like the and touching the annotation button I noticed that the trigger lead came up every time I touched the it's not going to do it now and probably have to set up the configurations but that's how I discovered the problem here sorry I've got to go back knowing thing about the scope by the way you put in auto mode you hit single it doesn't take it out of auto mode like I want it to go when I press that single button I want it to just go into normal mode and be ready to trigger I don't like the way that operators do it's not a bug it's just an undesirable feature in my opinion anyway so let's actually compare that to many other oscilloscopes are having a lab and see if this is a common problem in oscilloscopes mic micro phonics on the multi-layer ceramic capacitors on the front end hmm but by the way um this is like a high that you know this is a high frequency tap right so this is a relatively you know it's a pretty high frequency tap what is that you know I you can go in there at the time base and measure it but also you can get the lower frequency thump now if I actually do the bench it's you know you can see it coming through but it's reasonably well isolated from the bench presumably because it's got you know big huge rubber feet on the bottom there some of the biggest I've seen on any scope so that's going to dampen any vibration coming through the bench so I wouldn't be too concerned about that with them it we can go down to 1 millivolt per division if we want but yeah it's not you know I'm not too well not too concerned about coming through the bench like that even though it is possible but as I said I just saw it like tapping on the screen and this is a big touchscreen it's designed to be touched and prodded and poked and everything else but you know I'm always tapping the Skype you don't go like that boom you know anyway let's compare with some different scopes shall we okay let's do another rohde & schwarz exactly the same settings two milliseconds 2 millivolts per division I'll keep the settings the same on all the Scopes we do here this is actually even though it's rohde & schwarz rohde schwarz brought out pay Meg like I don't know seven eight years ago a long time ago and this is actually a hey Meg designed and produced unit but it's rodent which was so anyway I'm saying it might even have some rohde schwarz tech rohde schwarz front end by the way that are to be to double for rohde & schwarz scope we just saw has its own 10-bit ADC it's absolutely killer there's no other scope in that price range with a 10-bit ADC in there and that's a rodents warts are designed ADC custom ADC in there so you know this might have a rohde schwarz ADC as well so let's have a look at this know it's possible to up not as not as big as well there we go got some low frequency stuff so the rodents warts really seem to be yeah really seem to be susceptible don't man that's not a particularly you know big thud really I mean stood you probably wouldn't do it normally but it's it just something see did we tap it there we go we can see that doing either you know I have to turn down the 1 millivolt or something to really start seeing that but that's not allowed in the bench you know and whoa you're that tap in the B and C's that's horrible mural okay let's have a look at the good old keysight 3000 our x-series shall we been around for a long time it's a stalwart let's give it a tap on top and it looks like it's doing it's doing it it's got something there oh yeah really got to hit it hard but it certainly it is possible it's much higher frequency content than what we were getting on the road and Schwarz one of course that's going to be totally dependent upon the construction of the multi-layer ceramic capacitors used inside these things so you know it's all to do with mechanical resonant modes of the piezoelectric material and the size of the plates and you know every other you know a ton of other it's not easy to get in here and do that but look one bit coupled through to channel 1 & 2 there - yeah okay yep it's getting through whoa oh that's a shocker in it but that's some real high frequency stuff going on there 200 microseconds per division so much higher frequency but you know it's still doing the business so I'd say the keysight one is fairly susceptible as well the brand-spanking-new not even released yet that's not the correct number it's going to be the 1202 XE Sigler this is the only one in the wild in the world apparently by GM once again 2 millivolts are per division this can go down to 500 micro volts so let's actually turn that down to 500 micro volts good having separate controls there oh there we go oh wow jeez is not much is there not well yeah I can see that really got a whack ah can I even look like that I can't I can't is a is good from a point of view of you know tapping on the box but if we yep we can see that coming up definitely if we are tap that once again like the keysight very high frequency er stuff they're being coupled through so you know but this one doesn't have the issue like you know touching the screen touching the top of the box unless you and directly couple through to the B and CS this one's rock-solid and the good old Roy gold es 1054 Z once again 2 millisecond here 2 millivolts per division 2 millisecond time base there and yep wow that's actually Wow that's potentially what that's got to be is that that is worse than the road and Schwartz is it where it's on par Wow I'm just gently gently tapping the top of that geez I thought the road and Schwartz was ah man that's terrible Wow top on the band see there there we go once again that's like just totally saturated that we yep even tapping on the second channel is enough to trigger channel one Wow I am bellied I am barely touching that seriously Wow that is terrible what a shocker we try keysight's new IDs Oh ex 1100 are 1000 x-series our scope and was a little bit that'll be going on there once again 2 millivolts per division I'm going to whack it pretty hard to do anything doesn't do the low frequency stuff rock-solid on the low freq or maybe yeah if you're lucky jeez but let's uh yep yep there we go we can get it once you directly couple in there you get it every time don't you jeez anyway alright the GW inspected es 1104 B sorry but I don't still can't get over how sort of I believe this scope is I'm sorry for any fans of it out there see it okay scope but it's you know anyway well low frequency stuff is not it's got some low frequency stuff in there let's try and single Wow yeah maybe in channel 4 there but geez you really have to work it hard generally that's pretty solid plastic poker oh you really have to go to town you really have to get you know nothing really got to get ah quite vicious with it before it'll do anything Wow wow that's probably the best isn't it is that the best on the BNC is that we've seen that's that's pretty good compared to the others that's not bad at all and the Tektronix MDO 3000 series scope once again 2 millivolts per division 2 milliseconds got the trigger point just above our channel 1 there ah it's pretty awesome that's pretty awesome this one looks like the best so far bingo we got the front panel but it Hey it requires you know a significant little significant little work there you know so yeah we've got the susceptibility in here maybe not as good as the GW in stick we just saw it I think from memory but yeah as far as actual wire case coupling through to the front end goes no this one is the best so far rock-solid and probably the equally ugly Teledyne lacroix waved yet touch three five four I can just switch this on because it's boot timers are ridiculously quick look at that um so I've already set it up to millivolts all the rest of it let's put in single mode jeez having a hard time yep not susceptible whatsoever something else fell down on the bench said let's go channel one oh hello yep yep that's pretty violent that's pretty violent yep I'm just touching that is that is that the worst one perhaps Teledyne Lacroix it's not cut oh yeah you got a couple through got a trigger off that channel that could potentially be the worst in terms of the B and C I'm just gently touching that I mean low-frequency stuff not all you really need that high frequency even a gentle tap like that that is really that is really quite that's feather touch wow it's a most susceptible I suspect and the Rye gold 2000 series yep it's acceptable from two low frequency and yet high frequency but not it's about average let's try to be and see oh yeah thank you very much look at that and I know you want to see old school let's get the HP fifty four six one six B and give it a ball yep we can do exactly the same thing but give it a whack on a Chevy wah that's fine and dandy even on the case down here Wow that's the shield in metal shielding for the front end you really have to tap the B and C to get that directly coupled to the front end coupling cap so there you go I think that's every scope I have in my lab I'm not entirely sure anyway I still contend that the road and Schwarz RTB to double a four is an issue because not only of course does it work on the BNC input it just goes absolutely off the scale but it's actually sorry yeah it is the most sensitive I mean what is what is that I mean that's you know let's go to 20 millivolts per division and yeah there we go so that's just a gentle tap let alone er let alone a good whack like that but not only that but the problem is this is touchscreen I mean I can just tap on the screen like that and cause that to come up especially if you've got like fingernails are for example and you you know which I don't but you tap it with the fingernail it's probably going to be a bit high frequency than if you've got you know a bit of a stump of a digit and calls out to go in but you don't want that when you just playing around with your touchscreen and this is a capacitive touchscreen so my non capacitive pokers not going to work but like in terms of actual are operating the screen but look what happens I mean if you did have one of these that you know even get capacitive pokers can't you I mean that's just ridiculous I'm just gently touching that and look at the amplitude wow that's just like a girl I swear like I'm not even holding that rigidly just like loosely going like that anywhere on the screen that's just that that's saying you can't have that and they advertise that their front E and I'm super low noise front end with their 10-bit ADC and custom blah blah blah and everything's fantastic until you actually use their big functional touchscreen that's just what is it a feature you could say that's a feature right so touch triggering whack triggering trademark hmm anyway hope you enjoy that catch you next time

Channel: EEVblog

Views: 150,292

Rating: 4.7888155 out of 5

Keywords: eevblog, video, Rohde & Schwarz, RTB2004, oscilloscope, capacitance, piezoelectric, tap, effect, touch screen, review, comparison, shootout, mlcc, ceramic capacitor, microphonic

Id: WE9pYUVvr00

Length: 18min 38sec (1118 seconds)

Published: Wed Mar 29 2017