MultiMeter

[lefty]

Hi,

I just signed up today and am new to the whole electronics game. I have a multimeter that I picked up years ago, a Sperry DM-4100A. It's served me well but I've been learning that there are some other features that would be helpful in the electronics world. I checked out Amazon and the web but just like everything else these days, there's almost too much information. I'd like to be able to check capacitors and maybe have an auto-ranging feature. Does anyone have a suggestion? This is strictly a hobby at this point. I hope this is the appropriate sub-forum for this type of question and apologize if not.

Thanks
Lefty

[rstofer]

There is a Test Equipment subforum that might be more appropriate but the management doesn't care for duplicate posts.

In the sticky section of the Test Equipment forum there is at least one thread dealing with DMMs.

Everybody will have their favorite, some will suggest that either of Dave's (our host) DMMs are just right for the job (I have both) and others will expound on the CAT ratings and how high they ought to be. If you want to mess with mains, you should probably pay attention to the CAT ratings. 

For ordinary electronics work, there are some high dollar answers and some low dollar answers and everything in between.

This question comes up about every other week and there is a Search feature.  The replies, by contributor, don't change much over time.

You need 3 DMMs so think about that before you start spending a lot on one meter.

As I said, I have a bunch of meters including a high dollar Fluke, both of Dave's meters and a mix of others.  The one I USE is the inexpensive Aneng 8008.  It's a really handy meter and, yes, it measures capacitance.

https://www.amazon.com/Alloet-True-RMS-Digital-Multimeter-Voltage/dp/B072JMBLJS

[rstofer]

For the most part, unless the meter is from a VERY reputable manufacturer, the CAT ratings are bull-twinkle.  There is a thread over in Test Equipment (sticky, I believe) where one of the members has done a lot of testing.

I try to avoid working on mains and, when I do, I'm not using a DMM.  Why do I need 3 or 4 decimal places in a value I can't change?  A simple 'Wiggy' (or Knopp) will do a better job.  And, yes, I used to use these to make a living and I have had one version or another for about 56 years.  That's when I started work, I was using them for several years around the house before that.  My dad was an electrician...

https://www.amazon.com/Knopp-K-60-Cat-Number-14460/dp/B003A7T5KG

https://www.amazon.com/INDUSTRIES-61-065-Vol-Test-Voltage-Tester/dp/B000BVNSLG

The theme is that these are 'solenoid' type testers and they vibrate or bounce in your hand when you get something hot.  You don't need to look down, you don't need to look at a meter, you can keep your attention on the thing you're probing.

Clearly of no value in electronics...

[rstofer]

Dave did a video on the Aneng 8008

[bob91343]

It's a gamble to buy a meter when your requirements are too general.  Or, for that matter, when they are too specific.

The world is running over with meters.  In my ham shack/electronics lab I have about 15 or 20 of them, some analog and some digital, most are old.  Not to speak of oscilloscopes and signal generators and component testers and spectrum analyzers.

My suggestion is to decide what you want to do and then ask around for suggestions.  Each thing you want to do will come with a plethora of options.  You want to measure a capacitor?  Just with that, you will need to decide how accurately, at what frequency, and whether the parasitic parameters are important (ESR, ESL, breakdown, leakage, self resonance, temperature coefficient, etc.).  Similar issues exist for any other kind of component.

To measure volts, well there is input impedance, accuracy, frequency response, waveform effect, etc.

I could go on but you probably get the point.  Save your money until you see something that looks good at a decent price and that answers at least some of your list items.

For starters, you can pick up a cheapie Harbor Freight unit for almost nothing (and sometimes even nothing) and that will measure a lot of things accurately enough for many purposes.  I recommend what I call the Chinese Magic Box that measures resistors, transistors, diodes, capacitors, and inductors.  It also identifies the pinout of transistors.  They can be had for just a few bucks online; do a search on Mega328 I think it is.

Go to swap meets; it's amazing how much you can learn and how nice everyone can be to help.  You can see what all the parts look and feel like and how much they might be worth.

[magic]

IMO DMMs suck for capacitors. They are good for volts, amps and ohms; anything more is an afterthought.

I have bought the common LC100 meter which AFAIK is some DIY project cloned and mass produced in Asia these days. Much more resolution that any DMM in the price range and can be modded to support stiff test fixtures which don't change their stray capacitance as you plug and unplug pF-sized capacitors for testing. I have even used it to measure single digit pF capacitances of diodes and transistors and got results close to the datasheet spec.

More advanced meters can also measure ESR. Again, something you probably won't find for the same price in any DMM.

[AVGresponding]

For a hobbyist who's not going to be probing dangerous voltages/currents, cheap Aneng or Uni-T meters are perfectly adequate (I have a UT139C for such purposes, and numerous Flukes, TTi's and others for more serious work).

For capacitors, well these meters will measure the capacitance to a useful degree of accuracy, but you'll not see ESR measurement (which is probably the most relevant additional factor for general hobby/repair purposes), so for that I would recommend one of the many cheaply available LCR meter kits like this.

[rdl]

It's good to have more than one DMM. If I was just starting out I'd get the Aneng AN8008 and one from the Uni-T UT136 series. You can get both for less than $50. It's also very nice to have a bench style meter, not so much for more accuracy but for convenience. They plug in the wall and don't need batteries. They can sit on a shelf, up out of the way and are at least somewhat stackable. You can find cheap ones under $200 that'll do the job fine. VC8145 is one of the many.

[lefty]

This is all excellent info. Thank you very much. I'll check all of those devices out, as well as the equipment subforum.

But you all have pretty much hit it on the head. I won't be poking around in mains with these. I just like being able to fix stuff myself so I guess diagnosis /repair of my own stuff was the driving force behind my interest.

Thanks again.

[lefty]

Well, I just perused the equipment section quickly over my morning coffee and it's official....mind blown.

I did realize though, just like anything, there's no one tool that's perfect for everything. I guess that's a universal concept one learns as they get older.

[SpecialK]

Just buy the fanciest meter Canadian Tire has when it's on sale for 50% off.

[Wimberleytech]

I second the recommendations for the following:
Aneng DMM
LC100 component tester (or equivalent...these go by different names--search ebay for "component tester")

[rstofer]

It's true that DMMs aren't the very best tool for capacitors and they don't generally do anything with inductors.  I view that as a separate issue.

I have been doing this stuff for more than 60 years and it is only last year that I bought an LCR meter.  It is my least used piece of test equipment.  There was a discussion about it, the DE-5000, last week.  Maybe Search for it.

The DE-5000 does give series and parallel resistance for inductors and capacitors which might be handy under some circumstances.  It also gives impedance at a range of frequencies (100 Hz to 100 kHz, fixed steps).  I bought it because my grandson is in college and this semester he has a course in Circuits (even though his major is ME).

It's kind of pricey at $125 (with the adapters) for as little use as I'll ever have for it.  But that's just me, I pretty much play in the digital part of the electronics sandbox.

https://www.amazon.com/5000-Handheld-LCR-Meter-accessories/dp/B00S298KJO

I bought a couple of bench meters when that pay-to-learn electronics school went out of business.  They were all over eBay.  These too are seldom used.  They are really nice meters but neither one measure capacitance or inductance.

Until you are settled in some particular corner of the electronics sandbox, you should probably avoid spending a lot of money on dedicated equipment.   Ham Radio is not at all the same as Audio and neither are the same as Digital or <whatever> and the equipment needs vary significantly.

There is also a tendency to worship increasing 'counts' on DMMs.  What good are they?  If you get 3 decimal digits, that is close enough for all practical purposes.  More than close enough considering tolerances.  When I was in college, there were no calculators, we did everything with a slide rule with, what, 2 digits?  3 digits at most?  I'd venture to say that the Apollo program was designed with slide rules.  I knew some of the engineers working on the Atlas Missile Program and each of them carried a pocket slide rule.  Measuring 100V to the nearest uV is kind of silly.

As Dave shows, that little Aneng 8008 is pretty darn accurate.

[lefty]

Right. I may be a bit premature since I just started tinkering around. I still have a lot of learning to do before I even know what I'm doing. By the way, I have one of those slide rules. MICRONTA with a nice leather case. It was my Dad's. Dammed if I know how to use it.

[rstofer]

Move the left index of the C scale over '2' on the D scale.  Move the slider down to '3' on the C scale and you should read '6' on the D scale.

https://youtu.be/aj6_yYdt-Z8

[rstofer]

Right. I may be a bit premature since I just started tinkering around.

There are two different ways to play with electronics:  'Tinkering' and 'Designing' and, as you can imagine, designing is a lot more complex.  From a tinkering point of view, the Internet is full of projects that are fun to play with.  Designing from scratch takes a lot more knowledge of theory and, of course, math.

This forum is loaded with working EEs.  If you want to know something, this is the place to ask questions.  Somebody will know just about all there is to know about whatever it is you want to know.  The various forums on EEVblog are about as friendly as it gets.

Dave has some great videos, I especially like the Fundamentals Friday series.  When you get to op amps, watch Dave's videos including #600:

https://youtu.be/7FYHt5XviKc

Or the equally good videos from W2AEW including #75

https://youtu.be/K03Rom3Cs28

Now, maybe op amps aren't really of interest at the moment but a couple of concepts will be:  Ohm's Law and Kirchhoff's Laws.  Dave does a great job with Kirchhoff's Current Law in that op amp video.  It's absolutely magic the way the inverting input works.  And you will absolutely need Ohm's Law, Kirchhoff's Laws, Norton's Theorem and Thevenin's Theorem.  These are the fundamental tools of electronics.  Khan Academy Electrical Engineering curriculum can help.  As can all the other YouTube sites that deal with this stuff.

If you truly understand those 4 items, you will be far ahead of the average tinkerer.  Just understanding the negative feedback in video 600 moves you a long way down the road.  Op amps are magic!

[lefty]

Thanks for the encouragement. I've taken some online ed for electronics over the past couple weeks and have been watching a boatload of videos on youtube. so I'm still learning the basics and am truly a beginner. We'll see where it takes me. I might be a little too old for a new hobby/interest. I've been using everycircuit.com a bit, which I'm sure all here are aware of. I find it helpful as a lot of the early education is pure math. It's helpful to see how the math actually works in real life.

[rstofer]

I have never stumbled across EveryCircuit.com - interesting!

Most of us use LTspice for simulation.  TINA is another choice but not as common.  There are a lot of LTspice tutorials and there is a group over on Groups.Yahoo.com and there are a couple of fellows that are REALLY knowledgeable.  Which means, they are a week ahead of the rest of us.  Seriously, one of the moderators has direct access to the author.  It's free, BTW.

Circuit animation has its proponents and, unless it gets annoying, I kind of like it too.

Side comment:  Electronics is applied mathematics.  The nice thing is that much of what hobbyists want to do can be done without a whole lot of math.  A little algebra goes a long way!

One thing to remember:  Simulation is an hallucination of how a circuit might operate if the world was perfect.  And it isn't.  In general, simulations don't account for parasitics, they certainly don't account for what a breadboard does to performance and they rarely account for tolerances.  Simulation lives in a perfect world and we don't.  Don't be surprised when there are differences when you get to measuring things.

The real trick is to account for the differences.  What kinds of things in the physical world are causing the deviation from the simulation?

But it's all good!  There is a bit of education in everything!  It's even worth simulating the early DC Circuits where there are multiple power sources and several resistors.  Just to see if the simulation agrees with the math.

When I was stumbling through college back in the early '70s, I would have loved to have the tools we have today.  Then the emphasis could shift from trying to solve the stuff with a slide rule to actually understanding the material.

[lefty]

I appreciate that. The simulation is definitely helpful. I'm really stubborn when it comes to learning. I'm not satisfied with knowing how, I have to know why. The why isn't always available at the very beginning of learning something. I know it probably slows down my progress a lot of times when learning new stuff. I have a breadboard, some various components and such, odds and ends I picked up online in a kit.  But it's helpful to see it in some sort of action before I start a fire at my desk. I'm working on a power supply right now. Trying to figure out if I'm going to build one or buy one. I have several power supplies in my computer graveyard I've collected over the years. I figured I'd check out the equipment forum and then decide.

I downloaded LTSpice and will take a look at that as well. Thanks for the tip.

[rstofer]

I appreciate that. The simulation is definitely helpful. I'm really stubborn when it comes to learning. I'm not satisfied with knowing how, I have to know why. The why isn't always available at the very beginning of learning something.

Sometimes the 'why' isn't taught because it is assumed that the learner doesn't have the math skills to deal with calculus up to the level of differential equations.  We just toss out the current in a capacitor is C*dv/dt and there is no particular emphasis on dv/dt. From the equation, the current can get very high when dt (the time interval) gets very short - down in the ns region.  The thing is, there is parasitic series inductance that limits the current and there is series resistance as well.  The current can't get anywhere near that high.

On this topic, the LC Oscillator in EveryCircuit shows how the circuit oscillates but is totally unrealistic in the real world.  There is series resistance, intended or not, that dissipates energy and ultimately collapses the amplitude.  But the simulation doesn't show that!  It could be added, of course, and then you wind up with the more familiar form of Damped Harmonic Motion.  Again, the simulation isn't anywhere near reality.  It's just a thing with me...

 I know it probably slows down my progress a lot of times when learning new stuff. I have a breadboard, some various components and such, odds and ends I picked up online in a kit.  But it's helpful to see it in some sort of action before I start a fire at my desk. I'm working on a power supply right now. Trying to figure out if I'm going to build one or buy one. I have several power supplies in my computer graveyard I've collected over the years. I figured I'd check out the equipment forum and then decide.

I bought a Rigol DP832 a couple of years ago and it's a great supply - but it's pricey.  For decades I got along with batteries and wall warts plus the occasional fixed output supply - usually 5V.  PC supplies aren't highly regarded but if you plan to use one, at least fuse the outputs:

https://www.sparkfun.com/products/12867

There are MANY PS projects around here.  A few of them actually work properly but most have problems getting down to 0V and the current limit doesn't seem to be 100% successful.  You can build up fixed voltage supplies using something as simple as an LM7805 but why bother?  You can buy a 5V wall wart easier.  Everybody tries to make a DP832 in terms of functionality without really understanding how it works.  There's a reason they are expensive and it starts with that custom toroidal transformer with multiple secondary taps.

Another big difference between low end and high end power supplies is the way in which the current limit is set.  On the DP832, I just dial in a number.  On a low end PS, you short the output and set the maximum current.  For some reason, I don't like the idea of shorting a 12V 3A supply.  Maybe it's just me.

ETA:  Try to avoid switching style wall warts.  That is not always possible at higher currents but linear supplies will have less noise.

Here's a nice supply for breadboards:
https://www.seeedstudio.com/5V-3-3V-Breadboard-Power-Supply-p-566.html

DigiKey has the same kind of thing but I'm having a problem with their site right now.

Another approach:
https://www.sparkfun.com/products/114

I have some of these:
https://www.mouser.com/ProductDetail/Bud-Industries/BBP-32701?qs=sGAEpiMZZMve4%2FbfQkoj%252BN1%252BOwm3e8RAmsQ2NWu9W78%3D

Yet another approach:
https://store.digilentinc.com/powerbricks-breadboardable-dual-output-usb-power-supplies/

There a lot of ways to get power to your project without spending a lot of money on a power supply.

OTOH, the current limit and current trip feature of a modern supply (like the DP832) will save you a lot of escaping smoke problems.  Of course I recommend a decent lab supply but they are too pricey and maybe they can be deferred for awhile.

I downloaded LTSpice and will take a look at that as well. Thanks for the tip.

There are books about LTspice -- I haven't read any of them.

Another idea:  Instead of spending a lot of money on a lab power supply, why not spend it on a good oscilloscope?  You will need that a lot more than you need the features of a lab PS.  The Rigol DS1054Z is on my bench (as is a Tektronix 485) and it's a GREAT tool but it's getting old.  Search Test Equipment for riglol (spelling IS correct) and follow along to get the 100 MHz feature unlocked.

The new Siglent SDS1104X-E is newer and apparently a lot easier to use.  I think there is a thread over in Test Equipment on how to unlock the 200 MHz feature in a 100 MHz scope.  Saves about $300...  The Rigol was available when I went shopping.  Today I would probably buy the SDS1104X-E or spend the money for the SDS1204X-E

I would highly recommend 4 channels.  That is the specific reason I bought the Rigol - two channels won't display all the signals of an SPI serial transaction.  That the scope also decodes the data is a plus.

https://siglentna.com/digital-oscilloscopes/sds1000x-e-series-super-phosphor-oscilloscopes/

https://www.amazon.com/Rigol-DS1054Z-Digital-Oscilloscopes-Bandwidth/dp/B012938E76  Easily unlock for 100 MHz!

It's easy for me to spend other people's money!

[rstofer]

On the theme of equipment, I would suggest you at least consider the capabilities of the Digilent Analog Discovery 2.  This one gadget has a 2 channel Arbitrary Waveform Generator, a two channel Oscilloscope, a dual output power supply, 16 channels of digital input/output with protocol decoding and a lot of other features.

I have the feeling that a lot of folks just blow off this recommendation.  In my view for LEARNING electronics, there is nothing like it.  Every tool I need in a small, breadboard friendly package.  Maybe it is suboptimal for tinkering and I'll concede that when I want to see some arbitrary waveform, I might use my scope(s) but if the intent is to breadboard small circuits, there is no tool on the planet that comes close.

Read over the Features list and download the free Waveforms software.  There is a "Demo" device that will allow you to exercise the various features.  There are a lot of videos on YouTube and they are probably worth watching.

The problem is, it's expensive by the time you get it kitted out.  Heck, it starts out expensive even when just bare bones!  You can delay some of the add-ons and just use it the way it comes.  Or, think about buying 2 or 3 Breadboard Adapters.  You can then build up an experiment per breadboard and keep them assembled for a while.  The other stuff, like the BNC adapter and scope leads can wait.  BTW, you lose the differential input capability of the AD2 when you add the BNC connectors.  The shell of the BNC connector will be connected to earth ground through the PC - if the PC is grounded.  Be careful here!  I don't tend to use my BNC adapter very often but I have other scopes.  YMMV on this...

https://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

https://store.digilentinc.com/breadboard-adapter-for-analog-discovery/

Look in EveryCircuits -> Examples -> RC Step Response  I like to build this circuit with a 10k resistor and a 0.1 ufd capacitor.  I then hit it with a square wave (offset such that the voltage swings between 0V and, say, 1V) with about a 12 ms period.  That leaves 6 ms high and 6 ms low and since the time constant Tau = R*C = 1 ms, I get 6 Tau high and 6 Tau low.  We know from 1-e^-6 that we are 99.75% of fully charged/discharged in 6 * Tau.  Experiment!  Cut back to 3 Tau or stretch it out to 10 Tau.  Exercise your calculator to figure out the percentage of full charge.

The EveryCircuits video on the home page of their web site deals with this very circuit around 2:30  In the Example they settle on 5 Tau.  Fair enough but it's only 99.33% charged.

I can spend an entire morning with just these two parts and the AD2.  We know from ELI the ICE man that the current leads the voltage in a capacitive circuit and that it leads by 90 degrees.  Prove it!  You measure current using the differential input feature of the AD2 scope across the resistor (differential connection) and voltage across the capacitor on channel 2.  See attached  PhaseShift.png.  The yellow trace is current through the resistor (by measuring voltage across the resistor) and the blue trace is capacitor voltage.  You can see that the yellow trace leads the blue trace by 90 degrees - exactly what ELI the ICE man predicts.

https://www.khanacademy.org/science/electrical-engineering/ee-circuit-analysis-topic/ee-ac-analysis/v/ee-eli-the-ice-man

Or maybe you just want a Bode' Plot of the RC filter - see BodePlot.png  Note how the -3dB point occurs at 1/(2*pi*R*C) - I'm telling you, this stuff is magic!

See the section Cut-off Frequency and Phase Shift here:
https://www.electronics-tutorials.ws/filter/filter_2.html

I could go on for pages about this tool.  It really is the best thing around for learning - maybe that's why so many universities have adopted it.

I could put on a fairly long class using just those 2 parts and the AD2.  Wait until we get to transistors!

Alas, there is a difference between "learning electronics" and "tinkering with electronics".  The AD2 is more aligned with "learning electronics".  See the "Real Analog" course at Digilent.

A 27" scope screen is pretty cool!

ETA:  I added the AD2 plot of the forced response example discussed above.  10k Ohm, 0.1 ufd, Tau = 1 ms

[AVGresponding]

I would add that you should not rule out purchasing used, higher quality equipment.

All of my higher end gear is used, I reckon I've spent less than $1500, and have what would cost ten times that to buy new.

The Products section include many threads on test gear, the TEA (Test Equipment Anonymous) thread is in fact the most popular thread on the EEVBlog forums!

There's certainly plenty of advice to be had on finding, buying, and repairing this kind of gear.

[rstofer]

But the question is, can a beginner with essentially no skills or equipment actually fix anything that is defective?  And they need to know which pieces of gear can't be fixed at all.  Like those Tek scopes with unobtainium ICs.  And how many times has the statement been made that "you need a working scope to repair a defective scope".  Maybe you do, maybe you don't, but if you do and don't have one you're in a heap of trouble.

I bought my two bench meters and my Tek 485 from eBay and all 3 have been perfect.  But I didn't want another CRO, I wanted a DSO and they aren't particularly cheap on eBay.  The bench meters were cheap because of the dumping from that pay-to-learn college.  If they hadn't been cheap, I wouldn't have bought them.

In my view, buying used is a tremendous risk given the presumed lack of skills of the purchaser.

I might consider a power supply but, in spite of my outcome, I wouldn't recommend a scope unless it was recently refurbished and calibrated.  Unfortunately, these don't tend to be cheap.

[AVGresponding]

Perhaps I should have added "if necessary".

None of my gear has required anything more than minor repairs, and most of it hasn't needed repairing at all.

As for a scope, my main one is a TDS420A with all the options which I got for £90 shipped, and with 7 top quality probes included. It's old and out of date compared with modern stuff yes, but it's more than capable for my purposes. I'll eventually have to replace the NVRAM batteries of course, but for now they still have plenty of juice.
I have a Hameg 203-6 as well, useful for its component tester, and even though it's only a 20MHz 2 channel jobby, that's probably all a beginner would need. I paid £50 shipped iirc. A couple of the pushrods that connect internal switches to the front panel needed fixing is all.

I'd say that a DE-5000 is overkill for a beginner, those cheap Atmel 328 based component testers for around £5-10 are close enough; I have one and it's not a million miles away from a £2000 (if I'd bought it new     ) LCR meter I recently acquired.
Another advantage those have is their ability to identify type and pinout for most transistors and diodes, though I wouldn't trust the hfe readings.

I'd go so far as to say those little 328 based gizmos are an essential part of any EE toolbox, pro, am, or novice.

[rstofer]

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR1.TRC0.A0.H0.Xtds420a.TRS0&_nkw=tds420a&_sacat=0

That TDS420A is priced all over the map at eBay.  Some for a couple of hundred bucks and some for nearly a couple of thousand.  That's it's 4 channels and 200 MHz makes it very useful for the hobbyist but they first need to sort out the difference between the $200 versions and the $2000 versions.

While the TDS420A is 'digitizing', I'm not sure how it compares to a modern DSO.  These new fangled scopes do everything!  I bought the DS1054Z primarily to do decoding of SPI (without having to drag out my logic analyzer) and it works well for microcontroller projects.

The measurement capabilities of the modern DSO make it far more useful than a traditional CRO.  My 350 MHz Tek 485 is still here because it has bandwidth.  There's no way I would want to buy a DSO with similar bandwidth.

In any event, these are choices for the newcomer to make.  There are some old-dog scopes around that are perfectly adequate for those just starting out.

eBay has the DS1054Z for a couple of hundred bucks more that Amazon!

[lefty]

Thanks so much guys. You've given me a lot to go on and I appreciate it. This is by far the most helpful forum to which I belong. Having a ball trying to figure this stuff out.

[lefty]

I apologize if this has moved off-topic and if it just belongs somewhere else but I probably started in the wrong sub-forum to begin with...so here goes.

I have a bunch of PC's, some really old and some just a little old. Up until now, I would usually just pull out some things I would find useful for spare parts, cables, fans and such. Hardrives and power supplies if they were of substantial enough size. But I'm starting to think there may be way more usable parts but I'm too new to really know. Should I hold off and keep them around for when I really start to learn? Is there anything good in there that may come in handy?

[rstofer]

A lot of people unsolder motherboards with a hot air tool.  I can't see the effort involved for the cost of components that may or may not be marked.  I can buy all of the small parts for pennies and I'll know what they are.  Then again, I'm lazy.

As I said, a lot of people do strip the boards...

[AVGresponding]

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR1.TRC0.A0.H0.Xtds420a.TRS0&_nkw=tds420a&_sacat=0

That TDS420A is priced all over the map at eBay.  Some for a couple of hundred bucks and some for nearly a couple of thousand.  That's it's 4 channels and 200 MHz makes it very useful for the hobbyist but they first need to sort out the difference between the $200 versions and the $2000 versions.

While the TDS420A is 'digitizing', I'm not sure how it compares to a modern DSO.  These new fangled scopes do everything!  I bought the DS1054Z primarily to do decoding of SPI (without having to drag out my logic analyzer) and it works well for microcontroller projects.

The measurement capabilities of the modern DSO make it far more useful than a traditional CRO.  My 350 MHz Tek 485 is still here because it has bandwidth.  There's no way I would want to buy a DSO with similar bandwidth.

In any event, these are choices for the newcomer to make.  There are some old-dog scopes around that are perfectly adequate for those just starting out.

eBay has the DS1054Z for a couple of hundred bucks more that Amazon!

Yeah prices are all over the place, it probably depends on what options it has fitted and as I said, mine is fully loaded. To be fair I probably dropped a bit lucky on that.
As for the digitizing part, well, at a measly 100Ms/s, the absolute best you can expect is 40MHz bandwidth, with a regular waveform and a following wind!   
It goes into ET at the drop of a hat...

When I was working as a workshop EE testing/diagnosing/repairing UPSs in the way-back-when, all I had was a 20MHz Hameg and a Fluke 83, yet somehow I managed to fix stuff!

[rstofer]

So, it might get down to "buy a used analog scope for a couple of hundred bucks" or "buy a new Rigol DS1054Z for $350, with 4 channels and a warranty plus advanced features".   Or perhaps one of the newer Siglents.  I just don't see a future in having a CRO other than bandwidth and equivalent time sampling doesn't interest me at all.  Too much of what I do is "one and done" in terms of data transfers.  I REALLY like the "One Shot" feature of a DSO.

I remember building all of my early equipment:  Heathkit Oscilloscope, Heathkit VTVM, Heathkit VOM, Heathkit Power Supply, Heathkit Frequency Counter  - there's a theme here!

I actually built my first oscilloscope from a project in the ARRL Handbook circa 1958.  It was an interesting project for a 13 year old kid.
Over time, my early gear has migrated to storage and has been replaced by better stuff but much of it is still around.

[grizewald]

I may be biased (because I already own one), but the Rigol DS1054Z is great for the price. I bought mine as a "nearly new" directly from Rigol's EU web site so it came with a full warranty and a decent cut off the new price.

After receiving it and checking that it worked OK, I immediately unlocked it so that it now shows as a Rigol DS1104Z and has the full 100MHz bandwidth and all decoding options. With four channels, you can happily use the 'scope as a logic analyser and debug I²C and SPI bus traffic with full decoding.