When to buy an oscilloscope ?

[tggzzz]

From the time I left Uni until I got my own scope was well over 20 years. At times not having one was a PITA and needed some educated guesses to fix a fault or drop around to a mates place to borrow his a few times a year.

Now I have had one on the bench I wouldn't not have one again but if it broke today Electronics wouldn't cease because of it (or maybe I should buy a second just in case  ). They are a great tool used properly but not essential to all people playing with electronics depending on where they play.

Recommendations to 'Buy Now'  A over B but forget C from incomplete questions without knowing 'what' or if they really 'need' a product isn't an answer it is a sales pitch.

I agree with all of that; very sane.

But I question your TEA/GAS credentials if you only have one scope

[beanflying]

I should have added a word 'buy a second 'working' one' I do have two waiting for some loving 

[tggzzz]

I should have added a word 'buy a second 'working' one' I do have two waiting for some loving 

You are forgiven   Currently I only have a 465 in that queue.

[rstofer]

I still think the decision is pretty easy.  If a project has signals that wiggle, it's nice to be able to see them on a scope.  Up until then, a DMM will do the job just fine.

It would be simple if we could just say DC circuits -> DMM, AC circuits -> Scope but there is that pesky experiment of a capacitor charging.  It is taught in DC Circuits.  It's not until AC Circuits that we worry about the frequency response, phase shift and roll-off.  Assuming some kind of square wave input (astable 555?), watching the charge and discharge curves gives a lot of intuition to how timing circuits work.

[beanflying]

No one has said not to buy an Oscilloscope. What I question is that you MUST have one and buy one NOW or ASAP no matter what it is.

Time and again the question of Brand A over B comes up from people not knowing what they need or want, they just 'know' from reading here or watching YouTube they need Item 'X' (Scope, DMM, Power Supply, Iron, widget....) because 'everyone' has one.

Sometimes WE need to ask WHAT the OP wants to do with Item X and is likely to do with it Long before giving a specific recommendation.

[mrpackethead]

No one has said not to buy an Oscilloscope. What I question is that you MUST have one and buy one NOW or ASAP no matter what it is.

Time and again the question of Brand A over B comes up from people not knowing what they need or want, they just 'know' from reading here or watching YouTube they need Item 'X' (Scope, DMM, Power Supply, Iron, widget....) because 'everyone' has one.

Sometimes WE need to ask WHAT the OP wants to do with Item X and is likely to do with it Long before giving a specific recommendation.

Do you have a scope bean?

[beanflying]

I did have two working ones but sold off my Hantek due to non use after getting a Micsig 100Mhz 4ch with all the bells and whistles. Casually looking for a 400Mhz or better one but it is a really low priority and need with what I generally do. There is a BWD and a Philips on the shelf for restoration, these are just for fun sub 20Mhz units that cost me very little.

After not having a scope at all for a long while the $100 spent on the Hantek was a good way to relearn what I needed to before moving up the food chain a bit with a much better idea of what I needed and in my case it wasn't perhaps the usual suspects.

[tggzzz]

I still think the decision is pretty easy.  If a project has signals that wiggle, it's nice to be able to see them on a scope.  Up until then, a DMM will do the job just fine.

If it is an RF project, a scope is probably not the best tool.

It would be simple if we could just say DC circuits -> DMM, AC circuits -> Scope but there is that pesky experiment of a capacitor charging.  It is taught in DC Circuits.  It's not until AC Circuits that we worry about the frequency response, phase shift and roll-off.  Assuming some kind of square wave input (astable 555?), watching the charge and discharge curves gives a lot of intuition to how timing circuits work.

"No one has said not to buy an Oscilloscope. What I question is that you MUST have one and buy one NOW or ASAP no matter what it is."

[rstofer]

I still think the decision is pretty easy.  If a project has signals that wiggle, it's nice to be able to see them on a scope.  Up until then, a DMM will do the job just fine.

If it is an RF project, a scope is probably not the best tool.

It would be simple if we could just say DC circuits -> DMM, AC circuits -> Scope but there is that pesky experiment of a capacitor charging.  It is taught in DC Circuits.  It's not until AC Circuits that we worry about the frequency response, phase shift and roll-off.  Assuming some kind of square wave input (astable 555?), watching the charge and discharge curves gives a lot of intuition to how timing circuits work.

"No one has said not to buy an Oscilloscope. What I question is that you MUST have one and buy one NOW or ASAP no matter what it is."

From the OP "Started learning ...".  I'm just guessing but that probably doesn't mean GHz RF design or directed energy projects.  I would rather imagine it will turn out to be Arduino projects or perhaps some simple 555 projects and perhaps some transistor gadgets.  LEDs seem to come up a lot.  Oh, and op amps, everybody loves op amps!

I would expect frequencies to be modest and voltages to be reasonable.  Nothing in the OP suggests high voltage SMPSs.

Well, that sounds a lot like the stuff I do and the scopes we often discuss are more than adequate.  I sure wouldn't spend the money to even ship a used analog scope, much less buy one, given what the new entry level DSOs cost.  With a warranty...

Somehow, I have to believe these scopes would be adequate for a good long time.  They're inexpensive enough to be considered disposable or even dedicated to a project.  Right now my DS1054Z is hanging on top of my Comdyna GP-6 Analog Computer and there it may stay.  I really need an XY display for some experiments and YT is used all the time (pun intended).  The hole on top of my bench might just get filled with a Siglent SDS 1204X-E.  I'm still thinking about it...

The cost of ownership for something like the Rigol is pretty low.  If, in a few years, it comes up inadequate to expanded interests, dedicate it to a project or sell it and buy something else.  At $400, these things are really inexpensive for the capability.

I haven't reread the thread but I assume the topic of the Analog Discovery 2 has come up.  For a newcomer, I really think it is a mistake to overlook this tool since it is an electronics workbench in a small package.  If I could only have the AD2 or the 1054, it would be the AD2.  It won't handle high frequencies but there are ways to work around that problem.  I did it for years with my Heathkit 10 MHz scope.

I'll stand by my wiggling signals theory as the gateway for buying a scope.  Even simple 555 projects are more clearly understood by watching the THR input.  Sure, you can read all about the charging and discharging of the timing capacitor but you don't really know it until you see it.

How do you really understand PWM or servo signals without seeing them?  Yes, your project, no doubt copied and pasted from the Internet, will probably work but you still haven't actually seen why it works.  You haven't 'learned' anything.

Beyond simple DC voltage dividers, I don't see much future in electronics without a scope.  It is the tool that lets you see what is happening and seeing is believing (and learning).  Yup!  If the signal wiggles, a scope is the tool to use.

[alsetalokin4017]

Daddy, what's a capacitor charge/discharge curve?

[rstofer]

Very nice!  Just what I was thinking about when I brought it up.
Somehow Vc=Vin(1-e^-t/RC) and Vc = Vin(e^-t/RC) just don't do as much for me.

[tggzzz]

Very nice!  Just what I was thinking about when I brought it up.
Somehow Vc=Vin(1-e^-t/RC) and Vc = Vin(e^-t/RC) just don't do as much for me.

It is fun to see a practical manifestation of theory. But without the theory is is just another pretty picture.

So much of modern electronics requires maths that not understanding the  theoretical maths is career limiting.

[rstofer]

Very nice!  Just what I was thinking about when I brought it up.
Somehow Vc=Vin(1-e^-t/RC) and Vc = Vin(e^-t/RC) just don't do as much for me.

It is fun to see a practical manifestation of theory. But without the theory is is just another pretty picture.

So much of modern electronics requires maths that not understanding the  theoretical maths is career limiting.

True enough!  Without the math there is no career.  No degree either, for that matter.  Engineering is nothing more than applied math.  Lots and lots of math.  But that's not the case for the casual hobbyist.  They can get along fine with the fundamentals like Thevenin and Kirchhoff (both KVL and KCL).  If they find themselves without a particular tool, there's a lot of information on the Internet.

[vk6zgo]

Very nice!  Just what I was thinking about when I brought it up.
Somehow Vc=Vin(1-e^-t/RC) and Vc = Vin(e^-t/RC) just don't do as much for me.

Graph paper, pencil, & a reasonably active imagination, & you've got it!

[rstofer]

Very nice!  Just what I was thinking about when I brought it up.
Somehow Vc=Vin(1-e^-t/RC) and Vc = Vin(e^-t/RC) just don't do as much for me.

Graph paper, pencil, & a reasonably active imagination, & you've got it!

Yup!

Make the Y axis of the graph 10 units and scale that as 100%.  The X axis should go from 0 to 6 Tau where Tau is the time constant which is R in Ohms times C in Farads.  Then all you need are 7 pairs of numbers:  The time constant and the percent of full voltage:

Code: [Select]

Tau  % charge  Plot
0        0    (0, 0.0)
1       63    (1, 6.3)
2       86    (2, 8.6)
3       95    (3, 9.5)
4       98    (4, 9.8)
5       99    (5, 9.9)
6      100    (6,10.0)

Connect the dots.

Most people will only go to about 3 Tau and then just handwave the rest.
The important part is that the capacitor is 63% charged in one time constant and fully charged in six.
Or close enough...

[rstofer]

I think the OP has been officially scared away from this thread. The army of TEA is horrible, and TEA is a highly contagious disease.

Well, when you ask a group for an opinion, you have to expect some variance.  In this case, the recommendations are from "never" all the way down to "tomorrow" for buying that scope.

People can explain the logic behind their recommendations but, in the end, it's the OP's money and their choice to make.  As I have had some kind of scope for more than 6 decades, I am biased.  I can't imagine not being able to see what I'm doing.  Other opinions obviously vary.