Other Basic Electronics, Multimeters, & Oscilloscopes

This thread is about basic electrical, electronics, Multimeters, and Oscilloscopes. It is an outcome of interest that various members have expressed about these subjects.

@Janger , @Johnwa , and @kevin.decelles have all recently obtained a starter Oscilloscope so I think the timing is good for a thread like this.

The primary resource will be a book (available on Amazon in paper or kindle) called Electronics for Dummies by Kathleen Shamieh. The book isn't a requirement, but it always helps to have a reference of some kind to facilitate discussion. Other references might get added as the thread progresses.

I'm not picturing this thread as a course, just a good place to ask questions, find answers, and share knowledge and experience about basic electrical knowledge and testing.

As always, a good time and lots of great jokes are expected!

 

[Susquatch]

An introductory note of caution. High voltages are inherently dangerous. I consider anything above 30V to be dangerous enough to cause a shock and care is recommended especially for those with weak hearts.

Another word of caution about Oscilloscopes. Pay close attention to the warnings about not exceeding the input voltage limits of the scope. This mistake has killed more Scopes than any other. If the included Probes have a 10x switch, leave them set to 10x. And don't be tempted to measure 240V and above systems without making a divider circuit or better yet buying some 100x Probes.

We can add to the cautions in this post as the thread grows.

 

[Susquatch]

I've looked for 100x probes on Ali. There are lots, but by the time you add shipping the amazon price is in the ball park, much faster, and easily returnable.

High Voltage Oscilloscope Probe P4100 with Accessory Kit 100MHz 2000V 100:1 https://a.co/d/3t8UvmZ

If anyone has a better source, please post here.

Edit - just a short explanation of 10x and 100x probes. A probe is a very handy way of connecting an Oscilloscope to a circuit. The end usually has a small spring loaded clip hook that can easily attach to wires, component leads, and circuits. They also include an optional lead to attach to ground (or the negative side) of a circuit. Sometimes the probes come with interchangeable ends that include small blades and touch points to access different kinds of connections.

A 10x probe reduces the connected probe voltage by 10:1 so 120V becomes 12V at the Oscilloscope input. A 100x probe turns 120V into 1.2V. A 100x probe is a very safe way to connect an Oscilloscope to 240V because the scope only sees 2.4V

Some Scopes automatically compensate for the probe factor and reduce the display scale accordingly. But if not, it is easy enough to multiply or divide by 10 or 100 in your head.

If you use more than 1 probe at a time on a dual trace scope, only one of them should use the ground connector - the other should be removed or clipped to the cable sheathing. This avoids shorting one ground to another - which can be a serious problem when the two grounds are different!

 

[slow-poke]

Small comment about scopes and ground for novice scope users.

Almost all mains powered scopes use a EARTH grounded plug and that ground extends to the BNC connectors for the scope probes and ultimately to the small alligator clips that attach to the probes. For safety sake the ground should NOT be defeated!

All this to say that when connecting your probes to a circuit you need to be aware that anywhere you decide to connect those alligator clips to will be grounded via the scope. In some cases introducing a ground is okay and other times this could cause problems. If you don't understand the circuit, it would be unwise to simply connect and see what happens.

There is a trick when you really need to scope a point, and don't have a known safe ground point for. Use differential mode on the scope; connect one probe to the point of interest, and the other to a suitable reference point for that point and connect the two alligator clips to each other. In differential mode the scope will display the difference between the two probes and you don't introduce an inadvertent ground into the circuit.

There is a better way to probe circuits that are either high voltage or can't be grounded and that is to use a isolated differential probe (very handy, I use them all the time).

These use to be expensive years ago, but not anymore. Here is an example:

https://www.amazon.ca/Micsig-DP1001...locphy=9000664&hvtargid=pla-584521275992&th=1

 

[Susquatch]

These use to be expensive years ago, but not anymore. Here is an example:

Ya, still too expensive if you ask me. Don't forget the guys on this thread are not pros. The whole scope they bought cost less than that differential probe does!

Also, none of the inexpensive Scopes involved have grounded power connections. For all intents and purposes, they are like battery powered scopes with true floating grounds so the biggest risk is connecting to different grounds. That is why I recommend only using one ground not two.

When and if the need arises, you and I can show them how to do it without one of those differential probes.

 

[Susquatch]

Sometimes strange things happen for a reason. We had dinner tonight with another couple that my wife knows through her pickleball club. Turns out that the other hubby is an electronics guy - not a machinist though. For one reason or another we ended up talking about entry level Oscilloscopes. Turns out he has a recent model 1014D that he paid over $500 for. I didn't tell him they were 200 now, but I did tell him that I had been contemplating getting one to evaluate. I was delighted when he offered to loan it to me and I picked it up on our way home.



Except for that center column of buttons (which I have no clue about just yet but guessing that they prolly relate to the little windows to their left), it seems quite intuitive to use. On first blush, I like it! I especially like the screen - very crisp and easy to read.

I'm sure it will have various weaknesses that we will find in due time, but for the current price of $200 with free shipping, it seems like a no-brainer to me!

 

[Former Member]

There are significantly less expensive full featured options out there. Nano Scopes, VNA's and Spectrum Analyzers.

The biggest limitation on all of these devices is sensitivity and sample size. As long as you stay within the limits (unless you are doing lab grade work like you will) they work for you.

 

[slow-poke]

Turns out he has a recent model 1014D that he paid over $500 for. I didn't tell him they were 200 now, but I did tell him that I had been contemplating getting one to evaluate. I was delighted when he offered to loan it to me and I picked it up on our way home.

I'm sure it will have various weaknesses that we will find in due time, but for the current price of $200 with free shipping, it seems like a no-brainer to me!

Amazing value for $200, I can't fathom how the mfg makes any money?

Your evaluation will show:
1) The bandwidth is not 100MHz as advertised (closer to 20 or 30MHz in practice).
2) 0.5V resolution with 10x probe
3) Shallow memory depth
4) Early firmware has numerous bugs, many can be fixed with firmware upgrade.

If I had to choose between this model and the cell phone size ones I have played with, I would choose this one.

At the $200 price point and depending on what you need it for I would consider a gently used TEK TDS1012, not as flashy display wise but it may outlive the new one considering the encoders used on the 1014D. Tough call.

 

[Susquatch]

Amazing value for $200, I can't fathom how the mfg makes any money?

Me too.

Your evaluation will show:
1) The bandwidth is not 100MHz as advertised (closer to 20 or 30MHz in practice).

Yes, I am expecting under 50. But considering the applications that a new scope user will have, that's prolly still 50x better than needed. We will see.

2) 0.5V resolution with 10x probe

No biggie either. Half a volt is nothing in say a 24 volt system. At lower voltages, most users would use a 1x setting on the probes.

3) Shallow memory depth

It will be interesting to see if new users even use this.

4) Early firmware has numerous bugs, many can be fixed with firmware upgrade.

Ya, I plan to check on that first thing. I think I should get permission to do it though - just in case it bricks..... LOL!

If I had to choose between this model and the cell phone size ones I have played with, I would choose this one.

Me too. But prolly not if I already had a really good scope. I did get the little pocket sized FNIRSI DSO-TS3 myself a few weeks ago. I couldn't resist. I actually like the transistor tester a lot. In fact, the very first transistor I pulled out of my 2N2222 tray tested as PnP. My first reaction was "what can I expect for a $50 tester? ......" But a little more testing showed that it really was a PNP! Turns out it was a quality fallout of buying transistors in bulk 40 years ago. So I tested all the others - about 30 - and they were all ok. What were the odds of that!

So ya, my advice would be to get the hand held if you already have a nice scope, but the 1014 looks like a fantastic starter scope for a new user. It beats the HELL out of my first Heathkit Oscilloscope a million years ago!

At the $200 price point and depending on what you need it for I would consider a gently used TEK TDS1012, not as flashy display wise but it may outlive the new one considering the encoders used on the 1014D. Tough call.

Ya, tough call. For a new user, I think the 1014 is a GREAT DEAL and a good place to start. I think of it as a learning tool. It isn't likely to be anybody's forever scope.......

 

[Johnwa]

As per the specs, with the 1X probe the bandwidth is 5 MHz. It is specs as 100 with the 10X probe

 

[Susquatch]

As per the specs, with the 1X probe the bandwidth is 5 MHz. It is specs as 100 with the 10X probe

That's pretty normal for a scope to lose a lot of bandwidth with lower impedance. No worries. You are not likely to use it above 1 MHz. But if you bought a 1MHz scope and then had to derate it to 1 KHz, you prolly wouldn't be happy. I'll be giving my borrowed unit a bit of a shakedown as time passes. I'm really intrigued by what you get for the money as opposed to what you don't get vs a much more expensive scope.

The ability to look at a sensor input, output, translation to see what is really happening is solid gold. If I understood your first post, that's what you are after anyway.

 

[Former Member]

The biggest change in the last 10-15 years or so has be the processing chip for these devices along with all the additional circuits required on one one chip. The second is battery power and lower power requirements of these devices.

This requires significantly reduced costs as difficult specialized parts are no longer required.

Thank telecom and military for pushing this development.

 

[slow-poke]

As per the specs, with the 1X probe the bandwidth is 5 MHz. It is specs as 100 with the 10X probe.

Tested with 2GHz Agilent generator, 3dB point was about 27MHz. That being said Susquatch makes a good point that this is more than enough for most hobby work.

 

[slow-poke]

The biggest change in the last 10-15 years or so has be the processing chip for these devices along with all the additional circuits required on one one chip.

Yes, basically everything is running on a single FPGA.

 

[Susquatch]

2GHz Agilent generator

Where is the damn heart emoticon when you need it!

What can I say? I'm flat out jealous.

That said, if I had one of those I might not be happy with my Tektronix 400MHz 4 channel 2465B. Ya, ignorance is bliss....

 

[Lincoln20XX]

Yes, basically everything is running on a single FPGA.

My understanding is that this also frequently allows one to buy the lowest model of scope in a line, and then flash firmware that unlocks the features and resolution of the higher models.

This is because the manufacturers only do a single hardware revision, and nerf features through firmware.

Of course, the only legal way to do this is by paying the manufacturer for the appropriate licenses and inputting their unlock codes. Any other method would be in violation of various intellectual property things, and thus bad... Apparently.

 

[slow-poke]

My understanding is that this also frequently allows one to buy the lowest model of scope in a line, and then flash firmware that unlocks the features and resolution of the higher models.

This is because the manufacturers only do a single hardware revision, and nerf features through firmware.

Of course, the only legal way to do this is by paying the manufacturer for the appropriate licenses and inputting their unlock codes. Any other method would be in violation of various intellectual property things, and thus bad... Apparently.

Very true. I think for some they like the challenge as much as the prize. The code crackers over on EEVBLOG are a quite capable team. It's interesting to follow along as they attack from different angles and share what they find and then build on that shared knowledge as they progress. Countless spectrum analyzers and scopes have been "upgraded"

 

[slow-poke]

I'm far from a RF expert but I do some RF work from time to time. Spectrum analyzer is a great tool when you need it. Nothing wrong with a 2465B, very capable.

 

[Johnwa]

They’re already on it.

GitHub - pecostm32/FNIRSI-1013D-1014D-Hack: Resources gathered for reverse engineering the FNIRSI 1013D and 1014D scopes

Resources gathered for reverse engineering the FNIRSI 1013D and 1014D scopes - pecostm32/FNIRSI-1013D-1014D-Hack

github.com

 

[terry_g]

My 80's vintage Iwatsu SS-5706 looks like a fossil next to some of the new entry level scopes.