Another noob wants to buy a multimeter - Page 1
Forum section: electronics / beginners

author: nk7
author_rank: Contributor
timestamp: July 07, 2011, 08:03:54 am
content: Hi to all the techies. Yes I am a newbie in search of buying the 'perfect' (for my purposes) multimeter. Yes and before you suggest I read another topic or go milk a cow in amsterdam - here's a bit of background.I am a mech engineer student (last year) and know nothing of electrics and very very basic knowledge on multimeters but I want to learn much more. I require something for automotive and motorbike restoration use, aftermarket ecu replacements, tuning, fault finding etc (as a personal hobby) and in most cases problems in restoration arise from an electrical or electronics point of view. And since electrics are electrics whether in a car or toaster I figured I'd ask the electronics community (esp. someone with knowledge about electrics in cars etc) what their thoughts are. Just bounce some ideas back and forth.I have spent the last few months searching for this multimeter but cannot make my mind up due to conflicting views in forums especially. One thing I have noticed from my prowl on the net (that sounded dirty, yes I know sorry) that fluke is one of the best and if you pay big now you won't regret it.The multimeters I found interesting were (feel free to laugh, ignore, criticise, adjust or include your own suggestion):88V automotive one - yes i have looked at this already.the 87V (or 189 if people think this is a more suitable choice - thoughts anyone?? ??)and for the hell of having a multimeter with data logging and cool trends (although not sure how useful for my application???anyone?) - the 189IIThe comparisons I want to note are:1) the 88V does not have wide bandwidth (how important is this?)2) 88V does not do rms readings?3) 88V rpm measurement is apparently not that great - fluctuates - people suggested VR sensor or another tacho. Anyone used this mutimeter function? Can't I use the frequency function and do a few calcs?4) the 87V does not do pulse width - how does this affect me?5) 88V does not have motor drive measurement function. important? no?6)88v dc accuracy not as great as the other two...Apart from this, I want to say that I don't just want a basic multimeter with amps, volts and ohms - I want something more useful with features that I may not use now but will use eventually as I learn more from guys in the know like you. I want to spend once and never look back and hope that someone out there in the world wide web can help.I realise that's a lot of info to read through and you might read the first line and skip to another topic but if I could get any form of advice I would appreciate it.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 07, 2011, 08:44:51 am
content: Quote from: nk7 on July 07, 2011, 08:03:54 amIts best to milk a cow in Amsterdam, if you believe that.About troubleshooting cars, now days there is special analyzers.The automotive DMM's, they do same tricks, but its like a backup tool, not main.Currently, probably you need something robust + large display + simple to use.This forum is a nest of electronic engineers, and even me I am an exception,even so my father was cars electrician, end he did not based his carrier on a multimeter with an rpm probe.My advice are to get something simple for now,and get the special one, at the time that you will start practicing in the field.

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2011, 09:08:30 am
content: You won't need a precision electronics grade meter for automotive use.Automotive meters usually have RPM, and that's about it extra over a standard meter.The Fluke 88V is overkill IMO, but if you have the cash...This Amprobe one looks very automatic specific:http://amprobe.com/cgi-bin/pdc/viewprod.cgi?pid=2347&tid=1&type=elecAmprobe are owned by Fluke. Not quite the same quality, but the same company.I have no idea about cars, so don't know how useful those various features are.Dave.

author: nk7
author_rank: Contributor
timestamp: July 07, 2011, 09:28:06 am
content: Hey Kiriakos-GR thanks for the reply. i do want to start immediately - I have tools already just not many on the diagnostic side of things. Usually, we would have used the multimeter to deduce that there is a problem and perhaps specify areas affected then for further or 'proper' analysis use a scan tool etc which would be later down the track. And I'm not ready to fork out 3 grand for a oscilloscope unless it will be used a lot. A multimeter I would imagine i'd have around almost all the time. And a decent one will do nicely. Something that won't burst into flames as well..

author: nk7
author_rank: Contributor
timestamp: July 07, 2011, 09:37:14 am
content: Quote from: EEVblog on July 07, 2011, 09:08:30 amthanks for the help. It was just that when I look at prices for these multimeters - they are reasonably close (compared to the 88V which comes in a kit). Also, do you use trend capture? How is it useful for you? What things do you look for in a multimeter for your applications? Maybe this will help me make my mind up.Btw how does the amprobe differ in quality?Thanks

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 07, 2011, 09:59:32 am
content: Ok mister noob, you have lots of questions.Its best to start reading lots of useful threads, so to get an wider view.https://www.eevblog.com/forum/index.php?topic=718.0https://www.eevblog.com/forum/index.php?topic=660.msg7847#msg7847

author: nk7
author_rank: Contributor
timestamp: July 07, 2011, 10:02:27 am
content: Quote from: Kiriakos-GR on July 07, 2011, 09:59:32 amhaha Thanks. I appreciate your patience with me.

author: ipman
author_rank: Regular Contributor
timestamp: July 07, 2011, 10:20:42 am
content: Simply put, you cannot compare an automotive multimeter -Fluke 88 with something like Fluke 189/289.Even on the same type of measurement like DC: 88 has 0.1% accuracy, 189 has 0.025% for example. 6000 counts for 88 (19999 in high resolution), 50000 counts for 189. If you are interested in numbers, I can continue, but does not make any sense.88 was made for automotive use, it's a purpose-built multimeter, and it's best used at this application.BTW, 189 has pulse width and logging on the meter itself. But will not display the variation on it's screen.

author: nk7
author_rank: Contributor
timestamp: July 07, 2011, 10:35:51 am
content: Quote from: ipman on July 07, 2011, 10:20:42 amThanks for info.Granted I understand your point. But it was also due to a price similarity between these items that I decided to compare them. I thought since I was willing to pay for a 88V why not pay, say.. $20 - $40 more to get something with more precision albeit a feature like a rpm measure. For the moment that is as much difference as I can see from an automotive meter and a precision electronics meter.So do you think that high accuracy count won't really make a difference in troubleshooting compared to the 88 right? But considering prices...does it then come down to practicality and user-friendliness ? both are things which I cannot compare...any thoughts?Btw what place would pulse width have in automobiles?

author: ipman
author_rank: Regular Contributor
timestamp: July 07, 2011, 10:43:47 am
content: You cannot compare such tools based only on price.If your primary and urgent need is automotive, get an automotive one. You will end up having at leas two eventually.In automotive troubleshooting, there is no need to have a very precise reading. You cannot troubleshoot inside the ECU, for example, because it's sealed, so it will be swapped as a whole. If you want to troubleshoot electronic circuits in cars (supposing you can open without breaking them) the you will need an electronics-oriented one as 189-289.

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2011, 11:00:20 am
content: Quote from: nk7 on July 07, 2011, 10:35:51 amYou are into automotive, so it's likely automotive functions are essential in your field. It might be foolish to buy a meter without it.Buy a proper automotive meter and see how you go.The 88V has MUCH better battery life and is simpler to use for everyday use than the 189.Many professional electronics engineers would find they would hardly ever need the precision offered by the 189. So it's almost certain a newbie won't who's mainly into automotive. Forget buying the 189.Check these outhttp://www.tequipment.net/UeiADM4201.htmlhttp://www.tequipment.net/UEiADM5201.htmlI like the UEI, decent brand and only $137 for the basic one which will do what you want.The ADM5201 looks comprehensive and seems like a bargain. I'd rather have that than the Fluke 88V, and the extra money in my pocket if I was a beginner into auto.I had no idea you could get such features on an automotive meter:http://www.tequipment.net/pdf/UEi/ADM5201_datasheet.pdfMakes the Fluke 88V look pathetic really.I reviewed a UEI in my $100 shootout. A very nicely made solid meter. 3 year warranty.Stop looking, buy it!Dave.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 07, 2011, 01:03:20 pm
content: Although I would not normally recommend them,as they are not very useful for normal electronics work,one of the handheld DMM/Oscilloscope units may be very useful for trouble shooting in cars.In the past,I have done all my own car maintenance,& when I had a nasty intermittent ignition fault I borrowed one of the early Tektronix versions of these devices.I was able to determine that I was losing the input signal to the ECU from the distributor,which would have been very hard to see with an ordinary DMM.On a later occasion,I had a similar fault,but had to drag an old BWD out on the end of a power lead to do the same trick.Many of the sensors associated with the ECU deliver their data in pulse form,so the handheld DMM/'scopewould come in handy.VK6ZGO

author: MrPlacid
author_rank: Frequent Contributor
timestamp: July 07, 2011, 02:22:10 pm
content: Quote from: vk6zgo on July 07, 2011, 01:03:20 pmEven though I don't do automotive, I agree vk6zgo. I've heard people recommend the DMM/'scope like the S2405 (after scouring the web a year ago). However, I wouldn't recommend such meter to anyone here for electronics works.

author: ipman
author_rank: Regular Contributor
timestamp: July 07, 2011, 08:21:03 pm
content: It's not that bad, some electronic work can be done. But not measuring current consumption of a sleeping microcontroller.

author: nk7
author_rank: Contributor
timestamp: July 07, 2011, 11:15:39 pm
content: I hear you. Yes the dmm/do sounds pretty good but I will have to gauge how useful the scope portion will be even if the multimter side of things is pretty much a reproduction of an automotive multimeters. In saying that, man those scopes look nice - if people don't mind me quoting Dave.... that is definetelyporn for engineers. hahaHave people had good experiences withunisource(seintek) as a brand? Even better a unisource scope like the s2405 mentioned above? Comparing something like the s2405 and the uei adm5201 (that was suggested earlier) is about a $100 difference for extra features like that? Is it worth it? I guess for plotting o2 sensor readings and diagnosing faults would be perfect and very handy...but doesn't this become something similar to a 189II/289 with trend capture ?

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2011, 12:20:30 am
content: The s2405 had a 4 hour battery life, that could be massively frustrating.You really need a both, a proper meter with good battery life that just works for everyday measurements.You could get both and it's probably still less than a Fluke 88V?Dave.

author: nk7
author_rank: Contributor
timestamp: July 08, 2011, 01:02:41 am
content: Yes 4 hr battery life definitely frustrating. but buying both would be close to $650-$700 and there would be so much overlap in features. A lot of scopes I've found on their own without meter capabilities are bordering half-a-grand mark. It would be good to have scope functionality separate without the high price tag. But I suppose it is for a specific purpose so price would be higher.Any recommendations for scopes to accompany the uei adm5201 meter?

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2011, 01:45:55 am
content: The Velleman HPS10 has been popular for a long time.Dave.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 08, 2011, 01:57:26 am
content: I think there are DSO/DMMs about with the fairly basic oscilloscope features you need for automotive work at a lot less than $650.At that price you could almost buy a full featured Rigol 'scope&a cheapie DMM.I suggested the combined device because I am a bit dubious about the various functions on DMMs which purport to be able to give you sensible results on pulsed waveforms.If you were going to go into Electronics,I would recommend an older Fluke DMM & an Analog bench 'scope both bought secondhand,but when grovelling round inside cars,the DSO/DMM,(although they usually have quite low performance on the oscilloscope side) would offer a great deal more convenience.VK6ZGO

author: nk7
author_rank: Contributor
timestamp: July 08, 2011, 02:06:19 am
content: The only issue I have with DSO/DMM combos is they generally state up to a maximum of 5 hrs battery life which is pretty poor. Granted it is a restoration hobby not so much a full fledged business but would this not seem like a hindrance to you? So then you would still recommend something like the s2405 or their newer automotive inclined s2800 scope?Also, what do you mean bylow performance on the oscilloscope side?

author: ivan747
author_rank: Super Contributor
timestamp: July 08, 2011, 03:36:44 am
content: Quote from: EEVblog on July 08, 2011, 01:45:55 amFor that price I might consider getting a DSO nano. Here I have a quick comparison:Don't get me wrong, but the Velleman's specs are very bad nowadays.Consider, for example, high frequency noise. The display resolution is too low, the sampling memory is tiny. I took it apart and I have to say the construction is much better than the Nano. It uses proper DIP relays and some beefy input protection. A look at the main IC shows that they tried to sand of the part number but with a magnifying glass and lots of light I identified it. It was a Microchip brand so it had to e a PIC. I could figure out the numbers: P*C1*F45* The most common part with that designation is the PIC18F452. They probably updated to the PIC18F4520 because the former is not recommended for new designs.I don't know if a 18F series PIC can do most of the job of interfacing the whole thing. I think it has an external ADC.The DSO Nano uses MOSFETs for switching and doesn't have too much input protection. Also it probably isn't rugged enough for typical automotive use.Here's a table inspired in Dave's "comprehensive comparison chart":<--- The Nano was so bad I lost all my inspiration.JUST DISCOVERED THE SH*T BANDWIDTH OF THE DSO NANO:200KHZ!!!What a waste of time, really, I don't know why people buy this. I hereby accept any criticism to the Nano, due to it's crapness.It is as bad as those crap USB scopes!Sorry for the rant,Ivan

author: vk6zgo
author_rank: Super Contributor
timestamp: July 08, 2011, 05:19:59 am
content: Quote from: nk7 on July 08, 2011, 02:06:19 amThey usually do not have the high frequency response required for most Electronics work,or if they do,it is only at very short time/cm settings. (See Dave's blog #86 & the comments on that blog.)If it is a restoration project,you may only need basic DMM functions,depending on the age of the vehicle.Pre 1980s cars ,in the main,did not use computer control,so most of the signals are plain old DC.VK6ZGO

author: nk7
author_rank: Contributor
timestamp: July 09, 2011, 06:12:06 am
content: Quote from: vk6zgo on July 08, 2011, 05:19:59 amSo say something like a fluke 27 second hand and then a scope to supplement like the s2405/2800 or from velleman the HPS10/40?

author: vk6zgo
author_rank: Super Contributor
timestamp: July 09, 2011, 07:09:21 am
content: My multimeter is a Fluke 77,which I use for everything.If you got something like that,you could then grab a real cheapie from an auto store which will give you dwell & tacho functions as well as being a standby DMM.I haven't had anything to do with the s2405/2800,or the Velleman for that matter,but there seem to be a lot of the latter around,& they are well regarded.If you are doing a restoration in a garage with mains power available & don't need the portability,you may be able to get by with a cheap secondhand analog oscilloscope,or a USB type such as a PicoScope.The analog scope will be very useful if you want to have a bit of a play with Electronics other than just Automotive.The PicoScope is fairly limited for general Electronics,but is apparently widely used in Automotive circles.When you buy a PicoScope,they will sign you up for a very good Auto diagnostic site where you can see case histories of variousfaults on all sorts of vehicles.(My last work bought the PicoScope data logger,so we were automatically signed up).So it all depends on where you see yourself going in the future,The analog or the PicoScope are obviously limited in portability,(Although the PicoScope is powered from the USB,so can be used portable with a laptop)whereas the handhelds should be more useful if you are going to fix cars as a business.I assume that if you work for someone,they will supply the more high tech type equipment.I'm a retired Electronics Tech,but I like cars!VK6ZGO

author: nk7
author_rank: Contributor
timestamp: July 09, 2011, 07:45:53 am
content: Yeh I have heard about Pico but automotive kits generally are in the 2-4000 mark unless you look at older models for 2-500. I assume software is updatable to keep up with technology trends but I think you're right that might do the job. I wonder if these can be used with bikes as well. Checking ignition timings etc..Hmm analog. Would they require calibration due to age? How often do you need to do this? All I would need is a long wire probes and long power adaptor leads and I'm 'portable'. Yeh working at home garage mostly.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 09, 2011, 09:25:03 am
content: For what you're doing,it probably isn't a major drama,as most of these old beasts maintain their calibration fairly well.Most Analog Oscilloscopes don't have voltage & time readouts,so you have to learn how to read the displayIf you are using DC coupling,you can usually check the volts/div against an AA cell(check the batt voltage with a DMM first),(Australian practice is to call an Analog Oscilloscope a CRO,from Cathode Ray Oscilloscope,so I will use the term for convenience.)Set the CRO triggering to "AUTO".This should give you a straight line across the screen.If the volts/div is set to 0.5volts, an AA Ceil should cause the line to deflect verticallyapprox 1.5 divisions.Your timebase (time/div) can be checked against a 50Hz signal as 1 cycle at that frequency should appear on the CRO display as20mS duration.DON'T ram your probe into a mains socket!!.You can pick up enough 50Hz out of the air.A PAL TV line sync pulse is 4.7uS duration.If you look up w2aew's thread on Oscilloscopes in this forum,you will learn a lot about these wondrous devices.You may have to experiment when it comes to measuring ignition timing & suchlike,but you should be able to see the controlpulses into the ECU ,& the pulses out of the various sensors OK.VK6ZGO

author: nk7
author_rank: Contributor
timestamp: July 09, 2011, 09:30:51 am
content: Cheers for the info - yeh I had already started watching the mammoth video. had to take a break. I will definitely consider the analogue against digital - reminds of good ol' film cameras. I still have em and love them. When converted to digital they outperform a lot of expensive digital cameras if you do it right.But can analogues still do audio work as well - like checking for noise and sound levels etc? anyone know what sort of max frequencies I can expect in automotive...Will 2Mhz be enough? Noticed a special on Velleman HPS10SE on tequipment.net for $150 - not sure what 2nd hand analogues will set me back but not a seemingly bad price. Btw what brand and specs for analogues should i look out for? Will they offer diverse capabilities for these older models?

author: vk6zgo
author_rank: Super Contributor
timestamp: July 10, 2011, 04:02:45 am
content: Analogue CROs are real-time devices,so you can't hit "STOP" & save the display like a DSO.Well,actually, my Tektronix 7613canstore a waveform on the screen,but you can't manipulate the stored waveform like you can with a DSO.When you are looking at a real-time display,however,many CROs enable you to pick a particular point an the display & "zoom in " to it--they don't call it that,but it is a similar effect to "zooming in "with a DSO.Analogue units don't offer Fast Fourier Transforms(FFT) like DSOs,so you do not have the (fairly limited)ability to do spectral analysis that they offer.For Audio work,an Analogue CRO will enable you to look at wideband noise,power supply ripple,hum ,etc down to a few mV p-p.I doubt whether Automotive work requires very wide bandwidth,but it is unusual for even the cheapestAnalogue CRO to have less than 10MHz bandwidth.Brands? Well, you can do good work with even the most basic CRO,which in this context would probably be the single channel 10MHz units that Jaycar & Dick Smith were selling for around $150 new.You could probably pick up an old BWD quite cheaply,with similar specs to the above,but 35MHzbandwidth & a very nice display,but they are valve units,& also have a common faultwhich causes the sync circuit to fail.More sophisticated units will have multiple channels & in many cases,delayed timebases,which allow the"zooming" effect referred to above.Tektronix would be my first choice,particularly the 400 series,as they are reasonably cheap ,& are fairly small.Some of the later types are very nice,such as the 24xxx series ( I can't remember actual numbers offhand,but look through the threads here on EEVblog).I like the (old) 7000 series,but they are very large.(Tek for some unknown reason,saw fit to recycle the "7000" numbers).HP made some very nice CROs,but they don't have quite the same reputation for reliability as Tektronix.There are quite a few Philips units around,of varying capabilities,again not as "bullet proof" as Tek.BWD made a whole range of CROs,from the single channel ones referred to above,up to multi channel devices of similar performance to the Tektronix units.BWD tubes almost always have a bright display,notseeming to be so prone to loss of tube emission as other brands----but remember the sync problem on some models!Hameg are rugged units,& will probably be a bit pricey.There are a number of Trios,Telequipment Serviscopes,JVCs around,which may be OK,but are getting a bit long in the tooth & may not be worthwhile.Where to get them? eBay,the Equipment thread on this forum,Newspaper For Sales columns,Hamfests,word of mouth.As Analogue CROs don't "spoon-feed" you like DSOs,I'd recommend you sit down with your Oscilloscope & "have a bit of a play" to get used to interpreting the display.A Scientific Calculator will also help to check the relationships between time & frequency,etc.VK6ZGO

author: cs.dk
author_rank: Unknown
timestamp: July 10, 2011, 07:42:40 am
content: Quote from: vk6zgo on July 10, 2011, 04:02:45 amI've got my first CRO, an old 20 MHz dual channel Aaron BS-601. Borrowed a signal generator from a friend, and I'm beginning to figure out how to adjust the trigger, sweep time, etc.My question is, whats the formula for time/frequency calculations?Btw: There is a good post about older Tek scopes here:https://www.eevblog.com/forum/index.php?topic=3506.msg46786

author: vk6zgo
author_rank: Super Contributor
timestamp: July 10, 2011, 09:09:06 am
content: t in seconds= 1/f,where f is in Hzf in Hz=1/t,where t is in seconds.For instance, the duration of 1 cycle at 50Hz=1/50 second,or 20 milliseconds(mS),&the duration of 1 cycle at 1MHz =1/1000000 second,or 1 microsecond.(uS)VK6ZGO

author: cs.dk
author_rank: Unknown
timestamp: July 10, 2011, 09:19:30 am
content: Quote from: vk6zgo on July 10, 2011, 09:09:06 amThanks

author: nk7
author_rank: Contributor
timestamp: July 10, 2011, 09:42:01 am
content: So you vk6zgo you mentioned the Picoscope - I am assuming this is similar:http://www.ebay.com.au/itm/Hantek-Digital-USB-Osciliscope-DSO-2150-150MHz-/320725056618?pt=AU_B_I_Electrical_Test_Equipment&hash=item4aacb3fc6a. What are limitations compared to analogue - is the measurable frequency crap? Is this popular or does analogue still win? Just that when I consider older oscilloscopes - i don't really know how to fix them just in case they get sent as faulty and if there are expensive parts then...handheld DSO like velleman hps10 seems a better candidate. But you do say you can do a lot more with the analogues in comparison which is something I like. So many toys to choose from? Can I buy them all?!

author: Zero999
author_rank: Super Contributor
timestamp: July 10, 2011, 11:39:03 am
content: That so-called 150MHz 'scope only has 60MHz of analogue bandwidth which is presumably only any use for repetitive signals with only one channel enabled, use two and it'll drop to 30MHz. In one shot mode, the usable bandwidth is probably something like 15MHz, again with two channels, it's probably 7.5MHz. The maximum peak input voltage is only 35V and that's at frequencies under 10kHz.I've never used a USB 'scope before but everyone on the Internet seems to say they're shyte.

author: nk7
author_rank: Contributor
timestamp: July 10, 2011, 11:51:34 am
content: hmm okay. That's also prob why I can't find support articles for those items less than 4/5 years old. So if a cheap analogue can do everything a decent or perhaps an expensive handheld DSO can do apart from FFT analysis then maybe that's the way to go...?And if I do get faulty equipment, fixing that shouldn't be too bad since I can see that there is a lot of support for analogues here and on net it seems. Any ideas on what sorta costs involved in procuring a second hand analogue? Or some sort of aim - given the hps10 is only a $150 on tequpiment.net?

author: vk6zgo
author_rank: Super Contributor
timestamp: July 10, 2011, 04:06:35 pm
content: Well,the Tektronix 7613 100MHz mainframe with 2 vertical plugins (it can display 4 channels)& a delayed timebase plugins cost me $135 at a Hamfest,so this gives a fair idea of the likely cost of something similar.A 7613 is a bit too large for convenience in your application.If you are only going to use an oscilloscope around a car engine,the USB things may do the job,but they lack versatility compared to an analogue Cathode Ray Oscilloscope.VK6ZGO

author: Zero999
author_rank: Super Contributor
timestamp: July 10, 2011, 05:53:54 pm
content: How about buying a low end 25MHz 'scope, then hack it to 100MHz, when you've got more experience and the warranty has expired?

author: nk7
author_rank: Contributor
timestamp: July 11, 2011, 05:49:45 am
content: Heck if I can get something that high spec for only $135 with no issues I'd be very happy! I would work around the size and weight for that great a price.

author: saturation
author_rank: Super Contributor
timestamp: July 11, 2011, 10:35:35 am
content: For auto work, portability and some robustness is key, given your equipment will be taken to garages and such.http://autospeed.com/cms/title_Using-Oscilloscopes-on-Cars-Part-3/A_109873/article.htmlQuote from: nk7 on July 10, 2011, 11:51:34 am

author: nk7
author_rank: Contributor
timestamp: July 11, 2011, 10:45:07 am
content: Quote from: saturation on July 11, 2011, 10:35:35 amEven if most, if not all, work would be done in my own place??Also, what do you guys think of this analogue from jaycar - 10Mhz one. So my understanding is effective frequency that can be measured is essentially 10Mz/10 = 1Mhz effectively. Is that right? Btw it was mentioned that analogue can behackedor "overclocked" - is this by substituting hardware or getting like a 100:1 probe?

author: EEVblog
author_rank: Unknown
timestamp: July 11, 2011, 01:16:23 pm
content: Quote from: nk7 on July 11, 2011, 10:45:07 amIMO, better value can be had in a second hand 20MHz dual channel scope.But it is only $100 or so brand new with warranty.Single channel can be limiting.Dave.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 11, 2011, 01:42:16 pm
content: Quote from: vk6zgo on July 10, 2011, 09:09:06 amMy Agilent U1272A it can measure mS of wave forms, and at my Mains plug ( 50Hz) I got a reading, of 9.50mS ..If what I measured are pp , then if the 20mS if it is the total wave length, then we are both correct.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 11, 2011, 04:15:33 pm
content: Quote from: nk7 on July 11, 2011, 10:45:07 amThe low end OscilloscopeHero999was referring to was a digital unit.This idea sounds like a good option,after reading the linksaturationposted,as the Automotive signals don't seem to require very wide frequency response in the 'scope.As he suggests,if you want to play with general Electronics later,you can probably hack it to give better performance.With Analogue Oscilloscopes (CROs),what you see is what you get!A "10MHz" CRO will display amplitude for a 1 volt peak to peak (p-p) signal of,say ,1MHzas 1 volt p-p ,but with the same input voltage at a frequency of 10MHz,will show it as 0.707 volts p-p.In other words,the response from DC up stays pretty much the same,until a few MHz below 10MHz,it begins to fall off,until it reaches the level referred to above.As far as measuring frequency,you may or may not be able to show a single cycle & measure its duration,& hence calculate frequency at 10MHz with a "10MHz" CRO,depending on the timebase circuitry.A square wave signal of up to about 2MHz will be displayed without apparent distortion,but above that point will show increased distortion due to loss of the higher frequency components.Sine wavesquite a bit higher in frequency than 10MHz can be seen with these "10MHz" CROs by simply increasing the input sensitivity,but eventually they disappear into the noise.VK6ZGO

author: Zero999
author_rank: Super Contributor
timestamp: July 11, 2011, 04:55:49 pm
content: Quote from: vk6zgo on July 11, 2011, 04:15:33 pmWhat I meant was you can buy a Rigol 'scope, use it, learn a lot then, when the warranty has expired hack it to the full bandwidth.With many cheap digital 'scopes the only difference between the higher end and lower end of the model range is the software so if you know what you're doing, you can buy a 50MHz 'scope and modify it to 100MHz. The manufacturers obviously don't want you doing this so is invalidates the warranty.Quote from: EEVblog on July 11, 2011, 01:16:23 pmYes, I'd never recommend a single channel 'scope to anyone.

author: saturation
author_rank: Super Contributor
timestamp: July 11, 2011, 05:32:05 pm
content: Yes. Its easier to take the scope to the car, than the car to scope, unless you are pulling a part out for bench top analysis. Bench scopes generally do not float its inputs, and are tied to ground; for overall safety for your scope its preferable to have gear with full floating inputs, like the cheap Velleman. Automotive waveforms are not very demanding in bandwidth, but some, like spark plug outputs are in the kV relative to car ground, but to earth ground it can be far worse ... even the operating voltages within the ECU can be high, and what that is relative to earth ground I know not.If you need a bench scope for electronics, its best to get it for that purpose and get a specific one for in-car work.Quote from: nk7 on July 11, 2011, 10:45:07 am

author: nk7
author_rank: Contributor
timestamp: July 11, 2011, 11:21:47 pm
content: Quote from: saturation on July 11, 2011, 05:32:05 pmWhat do you mean by full floating inputs? Is that floating point numbers..as in programming or something else? yeh the Velleman would be good for quick jobs even if it is only 1 channel. Yeh I will work mostly at home in the garage - but if I do take it somewhere else and need a a scope, a portable would come in handy. So are you saying that moving a CRO/analogue around isn't particularly safe for the scope? It would either be sitting inside on the car seat or on a table (that can be wheeled around) when looking under the hood.I found some cheap analogues on ebay here in Oz if anyone would care to comment on:1) Kenwood CS1021http://www.ebay.com.au/itm/Kenwood-CS1021-2ch-20MHz-Oscilloscope-/370524265455?pt=AU_B_I_Electrical_Test_Equipment&hash=item5644f79bef2) Digitec 20MHZhttp://www.ebay.com.au/itm/Oscilloscope-Digitec-20MHZ-Dual-Trace-Near-New-/220811758055?pt=AU_B_I_Electrical_Test_Equipment&hash=item33696809e73) BWD 530Ahttp://www.ebay.com.au/itm/BWD-OSCILLOSCOPE-Model-530A-made-Melbourne-LQQK-/180691538341?pt=AU_Electronics_Vintage_Electronics&hash=item2a120e11a54) Tektronix type 422http://www.ebay.com.au/itm/Tektronix-type-422-oscilloscope-15-MHz-/330587200436?pt=AU_B_I_Electrical_Test_Equipment&hash=item4cf8885bb4and 5) Tektronix 2225http://www.ebay.com.au/itm/Tektronix-2225-50MHz-oscilloscope-/330587201570?pt=AU_B_I_Electrical_Test_Equipment&hash=item4cf8886022I tried to look for dual trace and ones that are not being sold 'as is'.ThanksN

author: vk6zgo
author_rank: Super Contributor
timestamp: July 12, 2011, 06:13:27 am
content: "Automotive waveforms are not very demanding in bandwidth, but some, like spark plug outputs are in the kV relative to car ground, but to earth ground it can be far worse ... even the operating voltages within the ECU can be high, and what that is relative to earth ground I know not."A car is normally an isolated system,with the chassis as the reference point,so the voltage at some high voltage test point with respect to mains earth could be almost anything -but it willalwaysbe lower than that at the same point with respect to the car chassis.Normally, the only connection to the mains earth will be via capacitance between the car chassis & earth, in parallel with the quite high resistance of the car tyres.Of course,if the Oscilloscope has an earthed connection,the car chassis goes to earth potential,so thevoltages w.r.t mains earth & chassis become the same.Voltages "floating" w.r.t car chassis are not at all common in Automotive equipment,so using a "floating"input is not necessary for that reason either.nk7:- A "floating" input just means that neither side of the input is connected tothe common side of the 'scope power supply--in the case of a mains operated unit--mains earth.You would not attach a CRO probe to the 30kV or so of the Spark plug leads,but anything else in a car is no more than about 400 volts.Voltages of this level are commonly observed with a X10 probe when working on CRT type monitors,or Tube type radios & Amplifiers.Professional Auto tester units usually have special pickups that can read Spark voltages,but these(mains operated) units are extremely expensive.Apart from being awkward to handle,using bench 'scopes in Auto situations does present the possibility of breaching the insulation of the mains lead in some of the mechanicals & elevating the car chassis to mains potential.VK6ZGO

author: nk7
author_rank: Contributor
timestamp: July 13, 2011, 10:28:28 am
content: Quote from: vk6zgo on July 12, 2011, 06:13:27 amWith this then I can guess that you are saying perhaps handheld DSO like HPS10 is the way to go for automotive and if I do want to get into electronics (which I do at a later stage) look for a second hand oscilloscope to get me started. Although I was trying to think of ways for making the CRO work (in terms of portability) the handheld is prob the best option apart from being inferior in a lot of its specs.