Oscilloscope training class (long)

[DSE_Kid]

Brilliant stuff! 

[K5_489]

Wow...I'm 40 years old now, have been on the internet for over 20 years, and this is, seriously, the very first time I've signed up for a forum with a specific question/need in mind which was actually answered by an easily found sticky post.  Well, at least I assume it will be..just registered a few minutes ago, and haven't yet watched the video, but based on the contents list, I believe it either will be or will at least get me much closer to an answer.  Specifically questioning what a large impedance mismatch between 'scope probe and 'scope input will mean.  I have a Tek 222PS 'scope with a 333.3K input impedance, the proper probes have long since become unobtanium, but I have a bunch of 1M impedance probes on the bench. 

I'm definitely looking forward to finding some time to watch the video here  

[L/C/R Putzer]

I read that Tektronix probes have a designed center conductor that is not a straight wire, but may have twists and bends for probe compensation. Besides the compensation adjustment.

[Figaro]

w2aew Alan Wolke, best teacher ever, professtional video's, Detailed , Every word to the point (all being said in short time)
Clear langauge (important for those whom English is not thier mother language), Nice pleasend quite voice, No ego ! Please if you meet him at the club, tell him this.

[casterle]

Armin - if you are interested in analog troubleshooting, I would highly recommend the "Troubleshooting Analog Circuits" book by Robert A. Pease.  Bob Pease just recently was killed, a tremendous loss to the Analog Design community.  Thankfully, he was a prolific writer, with a regular column (Pease Porridge) in the Electronic Design magazine.

I'm an old guy just getting started in analog - I hadn't heard of Mr. Pease before, so thank you for the introduction to this remarkable man.

Here's a link to a large collection of his writings:http://doc.xdevs.com/doc/_Lab/

[Mace_Hacker]

Thank you!!

[rpiloverbd]

Wish it was available during my University days....

[furnacemike]

Very cool! I have to watch this video! I'm kind of new in electronics and Oscilloscopes are a little intimidating. I actually bought a Hantek DSO5072P last year but I still haven't gotten to try it out yet.
Mike

[armandine2]

I have just dipped my toe in today with some practical scope training, by the arrival of my first digital bench oscilloscope.

A bit of queasy purchase, as getting the right price point,  brand, and model as a beginner is not without risk of disappointment.

At the moment though I'm happy enough with my decision of GW Instek MDO-2302A.

picture shows a ringing trace from my Keysight AWG at 4V pk-pk 2kHz square wave input.

[w2aew]

Congrats!  Ringing mostly due to the test lead inductance and unterminated output.

[armandine2]

Thanks for the pointer

How much is a measurement artefact and how much is the signal must be a recurring issue with analogue, I guess.

Ed.
Have just checked the original photo - 50ns per division

looks like a good excuse to do a calculation

Ed.
and of course ringing goes away with a bnc-to-bnc cable

[w2aew]

...and you've learned a valuable lesson on the detrimental effects of test lead (and ground lead) inductance. 

This video has some additional detail and examples:
https://youtu.be/zodpCuxwn_o

[armandine2]

yes, I kinda knew the good  and poor probe techniques before and I kinda knew that equipment doesn't always produce great square waves. Definitely a learning point in the degree of those two, for me.

[LOTO instruments]

Thumbs up!

[Sunnysingh241]

Hello everyone,
I am into robotics and electronics from quiet a while and I am going to buy an oscilloscope. I have a question that is I do mostly robotics using arduino and raspberry Pi and electronics project like fm and some other projects and I am also intersed in making my own microcontroller board so which scope should I buy.
A two channel Or a four channel. I have one model in my mind. The siglent sds1052dl+(500msps). Will this be enough for me.
And in general what's the lifespan of an dso

[Grandchuck]

The Siglent is a good choice and you should go for the 4-channel model if you can afford to.

[LogicalDave]

Adding my email response to this thread so others can view/comment:

The SDS1052DL+ (USD$289) doesn't seem competitive (price or features) with several Rigol scopes including:

• https://www.tequipment.net/Rigol/DS1102Z-E/Digital-Oscilloscopes/ (USD $279)
• https://www.tequipment.net/Rigol/DS1202Z-E/Digital-Oscilloscopes/?v=7401  (USD $339)

The Rigol scopes seem to offer superior features in every area including bandwidth, time-base accuracy, serial bus analysis (something you will probably appreciate in your application), memory depth, etc.  I simply don't see any advantage to the Siglent scope you are considering.  I have nothing against Siglent and have several pieces of their equipment including a SA/VNA and SG...I just don't see the particular scope you are considering as offering a good value when compared with the Rigol scopes.  I have had good experiences with Rigol, Siglent, and Owon; you have a wealth of good choices.

Also, the vendor I linked to above (TEquipment) sometimes offers a small discount to EEVblog members; it's worth asking if you're going to buy from them; I have purchased from them before and had good experiences.

[armandine2]

space was at a premium - yesterday - testing my perf-board common emitter stabilized transistor amplifier

so I had to face the Hantek 2C42 user interface , eventually getting a good setup.

My low voltage gain (I now realise) was probably down to not soldering the 100uf emitter cap in circuit 

[armandine2]

... a long night with Hantek to get Lissajous theory and practice to agree, as we know they must.

... it turns out triggering the Hantek for X-Y mode was a pita. And the frequency generator must be in internal sync to get a circle.

[lieinking]

I was going to post another thread but think this is okay here. I'm just starting electronics. I've been messing with capacitors and output signals from an arduino and would like to see the wave forms. That's pretty much all I would want an oscilloscope for right now. I don't know how long I'll continue the hobby so don't want to spend hundreds of pounds on equipment until I'm invested. Is there anyway around buying an oscilloscope or paying so much?

[Grandchuck]

You do not have to spend hundreds of pounds.  Look around and you will find many, many inexpensive offerings.  Also, used scopes can be great buys.

[xrunner]

You do not have to spend hundreds of pounds.  Look around and you will find many, many inexpensive offerings.  Also, used scopes can be great buys.

 

Is there anyway around buying an oscilloscope or paying so much?

The term "paying so much" is very subjective. What is the budget you are allowing yourself? You can get a used 20 MHz analog scope for under $150.

If "paying so much" means $25 to you, then you will have a hard time getting one. 

[radiohomebrewer2000]

Is there a tutorial video out there of someone showing how to do a stable measure of a AC waveform on an oscilloscope?

Really, a radio frequency wave - say about 2 MHz, 5 MHz, or 7 MHz.

I am interested in the numerical frequency and voltage. 

More specifically, I would like to measure a VFO or oscillator of a transceiver like a NorCal 40B CW Transceiver Kit.  There are various test points already on the PCB you can use to test.  However, using my old HP scope or my new Siglent scope, the measurements bounce around.

Here is a topic on EEVBlog already. 
https://www.eevblog.com/forum/rf-microwave/how-to-get-a-stable-measure-of-v-and-freq-using-an-oscilloscope-on-a-vfo/

I was just wondering if someone has a video or tutorial already of this scenario.

My old scope is a HP 54600B 100 MHz 2-channel digital scope from the early 1990s.
My new scope is a Siglent SDS814X HD 100 MHz 4-channel digital scope - this scope has a hardware frequency counter; however, it still requires a few seconds to display a stable measurement for the frequency.

In the link above, there was some good suggestions like using the average to get a stable reading.  Or add more periods.  Or create an inductor that has a few turns.   I do not think just getting the probe near the test point will work.   I have to touch the test point with the probe to get a reading.   If I want a stable frequency reading, I can hook it up to my old HP frequency counter.  But I just rather do it all in my scope.

There are "trigger" options in an oscilloscope, but I am clueless about them.   Besides, the wave form seems to display OK - stable.  It is the numerical readings I am interested in here.

Thanks in advance.

[shabaz]

Connecting anything to the output of the VFO will load it slightly, so it's not possible to precisely set it to a frequency using that method. However, you can use the scope to trim any adjustments in your circuit to see when the 'scope shows a signal that isn't weak and collapsing (such circuits will oscillate well in a range, and the output may collapse at extremes).
It probably won't look like an ideal sine-wave, this is OK. If you really want a voltage measurement, then even a peak-to-peak measurement (using cursors or automated measurements, either will be fine, there's no need for accuracy) is sufficient (I've not checked your documentation to see if p-p is what is being asked). If (say) the documentation says to adjust to 500mV p-p, then if it is 450mV or 550mV makes little difference.
If the measurement is very low, it may well collapse and produce unstable results. But there's a very good chance the unstable results are from a triggering issue. A screenshot/capture from your 'scope will help to narrow that down.

Once you're in the ballpark frequency based on what you've measured on the 'scope (automated measurements, but do a sanity check using cursors too, or with calculator and eyeballing it), and once the amplitude is in the ballpark you are expecting, then you could remove the 'scope, and then try to tune in your receiver to a known frequency transmission, and then fine-tune based on what you hear.

The screenshots below show two example 'scope traces for a particular VFO (different to your design, i.e. not related to that attached schematic) set to a center frequency, and to an extreme frequency.

Notice how the right-side screenshot looks more like a sinewave. However, that right-side screenshot actually shows a lower amplitude (see the volts per div setting on the screenshot), and and it is unstable (see the fuzziness on the trace).
The left side screenshot is actually the better setting. There, the amplitude is higher, and the signal is stable. The actual shape of it is less important, because it is normal for there to be harmonics that will cause that misshapeness.

[armandine2]

Today I used my bench scope to help me answer a tricky part of an old exam question.

Which I have been working on recently - see comments on w2aew's back to basics on current sinks.

A constant current sink NPN transistor circuit charges a 1000 micro Farad capacitor.
You are asked to draw V out (collector voltage, common emitter at 0V) against time.

A reasonably novel question as they go, perhaps.
[edited to add exam question/notes]