EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: drummerdimitri on February 09, 2015, 06:42:28 pm
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Hello,
I have ordered a rigol ds1054z since dave suggested it as a beginners' oscilloscope so I bought it to learn and tinker around electronics a bit more.
This is my first scope ever and I have no experience with using one whatsoever so please bare with me.
I was wondering how to use a scope's probes. Do I measure voltage the same way I do with a multimeter's probes for AC and DC voltages?
In other words, if I wanted to see how clean my mains voltage is, can I just hook up the ground pin to the neutral or live wire since we have no earth in Lebanon?
Also, according to the scope's specs, it is rated for Cat I 300V RMS so it should be fine to measure a 220V RMS AC signal right?
Finally, would I need to used the 10X attenuation switch when measuring mains voltage? Will it damage the scope if I kept it at 1X?
Thanks!
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Before you start poking around you need to watch this:
https://www.youtube.com/watch?v=xaELqAo4kkQ (https://www.youtube.com/watch?v=xaELqAo4kkQ)
There is also this very informative video, long and for analog scopes but will help you:
https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/ (https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/)
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In other words, if I wanted to see how clean my mains voltage is, can I just hook up the ground pin to the neutral or live wire since we have no earth in Lebanon?
The outside of the BNC connectors will be electrically connected to the ground lead and mains earth. As will ALL devices that share ground through the mains extender block. Typically any touchable metal chassis is grounded.
Spec says:
CAT I 300 Vrms, CAT II 100 Vrms, transient overvoltage 1000 Vpk
With RP2200 10:1 probe: CAT II 300 Vrms
Details: http://en.wikipedia.org/wiki/Measurement_category (http://en.wikipedia.org/wiki/Measurement_category)
Although you might be able to measure mains this way. I strongly advise against.
If you have to, buy a special probe or an oscilloscope with isolated channels.
Dave made a lot of video's regarding measuring. Here are a few:
https://www.youtube.com/watch?v=xaELqAo4kkQ (https://www.youtube.com/watch?v=xaELqAo4kkQ)
https://www.youtube.com/watch?v=OiAmER1OJh4 (https://www.youtube.com/watch?v=OiAmER1OJh4)
https://www.youtube.com/watch?v=PPgxFd97taY (https://www.youtube.com/watch?v=PPgxFd97taY)
https://www.youtube.com/watch?v=BFLZm4LbzQU (https://www.youtube.com/watch?v=BFLZm4LbzQU)
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Before you start poking around you need to watch this:
https://www.youtube.com/watch?v=xaELqAo4kkQ (https://www.youtube.com/watch?v=xaELqAo4kkQ)
There is also this very informative video, long and for analog scopes but will help you:
https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/ (https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/)
Thanks for the reply.
I have already watched Dave's video and here's my conclusion: I can connect my probe and ground pin to whatever point I like as long as there is no earth pin connected to ground am I right? Shouldnt be a problem then since we don't used ground in my country.
The second video is just too long and bad quality so didn't bother with it.
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In other words, if I wanted to see how clean my mains voltage is, can I just hook up the ground pin to the neutral or live wire since we have no earth in Lebanon?
The outside of the BNC connectors will be electrically connected to the ground lead and mains earth. As will ALL devices that share ground through the mains extender block. Typically any touchable metal chassis is grounded.
Spec says:
CAT I 300 Vrms, CAT II 100 Vrms, transient overvoltage 1000 Vpk
With RP2200 10:1 probe: CAT II 300 Vrms
Details: http://en.wikipedia.org/wiki/Measurement_category (http://en.wikipedia.org/wiki/Measurement_category)
Although you might be able to measure mains this way. I strongly advise against.
If you have to, buy a special probe or an oscilloscope with isolated channels.
Dave made a lot of video's regarding measuring. Here are a few:
https://www.youtube.com/watch?v=xaELqAo4kkQ (https://www.youtube.com/watch?v=xaELqAo4kkQ)
https://www.youtube.com/watch?v=OiAmER1OJh4 (https://www.youtube.com/watch?v=OiAmER1OJh4)
https://www.youtube.com/watch?v=PPgxFd97taY (https://www.youtube.com/watch?v=PPgxFd97taY)
https://www.youtube.com/watch?v=BFLZm4LbzQU (https://www.youtube.com/watch?v=BFLZm4LbzQU)
I understand that the BNC is shorted to the mains earth but like I said, We only use the neutral and live wires for power in Lebanon so I should be safe to probe around however I like correct?
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Even if you could do it, it's probably best to stay away from mains until you're more familiar with the scope. Have you not got some nice safe low voltage signal to play with first? Maybe try looking at the UART or SPI signal from a microcontroller. It's a changing low voltage signal and it makes you realise that digital isn't quite as neatly 1 or 0 as you expected.
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Even if you could do it, it's probably best to stay away from mains until you're more familiar with the scope. Have you not got some nice safe low voltage signal to play with first? Maybe try looking at the UART or SPI signal from a microcontroller. It's a changing low voltage signal and it makes you realise that digital isn't quite as neatly 1 or 0 as you expected.
Would a 9v AC power supply that is fed from the mains be a good starting point?
I should see the exact same waveform after the electricity passes through the transformer correct?
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Even if you could do it, it's probably best to stay away from mains until you're more familiar with the scope. Have you not got some nice safe low voltage signal to play with first? Maybe try looking at the UART or SPI signal from a microcontroller. It's a changing low voltage signal and it makes you realise that digital isn't quite as neatly 1 or 0 as you expected.
Would a 9v AC power supply that is fed from the mains be a good starting point?
I should see the exact same waveform after the electricity passes through the transformer correct?
:-+ :-+ :-+
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That sounds better. The 9v output *should* be isolated from the mains, although a quick resistance check with a multimeter should confirm this.
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That sounds better. The 9v output *should* be isolated from the mains, although a quick resistance check with a multimeter should confirm this.
Not a problem since I only use power cables with two pins since we don't have earth in my country.
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That sounds better. The 9v output *should* be isolated from the mains, although a quick resistance check with a multimeter should confirm this.
Not a problem since I only use power cables with two pins since we don't have earth in my country.
Voltage is not the primary concern.
Safety is.
The Energy from mains will blow tips off probes and damage circuitry......to be treated with the utmost respect.
This is my first scope ever and I have no experience with using one whatsoever so please bare with me.
Guys like you worry us.....enough knowledge to get yourself into trouble, but not enough to stay clear of it.
Stay with LV until you know your scope and understand electrical system better.
Be aware a SMPS on 230 VAC rectifes to ~ 325 V DC immediatly in excess of Rigol 300V 1x inputs.
I'd avise to get 100:1 probes for work in this region for additional safety and their higher voltage de-rating with frequency specs.
Safe use of an oscilloscope requires much more understanding that use of a DMM.
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I agree with the comments on understanding and learning about high powered circuits before I go around probing with my oscilloscope so I will educate myself before doing so.
Here's a video showing an awesome way of safely probing any AC lines like on would with a DMM without the problem of shorting and live wires to ground via the ground clip attached to the probe
https://www.youtube.com/watch?v=VWodjUSkYVE&list=FLZeo2EGeWAMceL7LdrP4UVw&index=1 (https://www.youtube.com/watch?v=VWodjUSkYVE&list=FLZeo2EGeWAMceL7LdrP4UVw&index=1)
Could I do this on my scope without any problems?
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Since the OP is a beginner in Electronics, I'd suggest staying away from the Mains and working with 15V or less.
PS why scope the mains anyway? What are you looking for?
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Since the OP is a beginner in Electronics, I'd suggest staying away from the Mains and working with 15V or less.
PS why scope the mains anyway? What are you looking for?
Not exactly a beginner. Just new to oscilloscopes :-DMM
I am looking to see how clean of a sine wave I am getting and to check for high voltage spikes in the signal.
I would also like to compare the mains output to the UPS output.
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Yes, the differential method is an accepted way to display waveforms without a GND reference.
This is my first scope ever and I have no experience with using one whatsoever so please bare with me.
Don't plan to run before you can walk.
Get some experience on low power, low energy circuits first.
After many years using DSO's, I always look for another way rather than expose myself or my gear to any risk.
Mistakes are just too easy to make, more so for the inexperienced.
Since the OP is a beginner in Electronics, I'd suggest staying away from the Mains and working with 15V or less.
PS why scope the mains anyway? What are you looking for?
Not exactly a beginner. Just new to oscilloscopes :-DMM
I am looking to see how clean of a sine wave I am getting and to check for high voltage spikes in the signal.
I would also like to compare the mains output to the UPS output.
There WILL be spikes and all sorts of rubbish on mains, accept it and get used to it.
Get the UPS manual and read the class of output it provides.
Stepped or pure?
Do you have a problem with equipment the UPS powers?
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It is a modified sine wave sing a pure sine wave UPS is too expensive.
I would be interested in seeing how much better or worse the output from a battery powered UPS is than the mains power.
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It is a modified sine wave sing a pure sine wave UPS is too expensive.
I would be interested in seeing how much better or worse the output from a battery powered UPS is than the mains power.
WHY
Don't you trust it as been built to spec?
Again you are demonstating your lack of knowledge.
Any device you power from it will have enough mains filtering to negate/smooth a stepped sine wave.
Leave it alone, go play with stuff that doesn't bite.
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BTW, looking at the output of a transformer does not necessarily show you the same waveform as the input. There are distortions that arise depending on the design of the transformer and its load.
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The danger of measuring mains is that when you hook up the scope without special probe. All BNC connector shields are live, as is the USB and other connector shields. As will the mains earth in your plug box on your desk, assuming you have one with earth.
When you plug in a metal USB stick, you get shocked. When you touch your metal cased pc, you get shocked.
This is not the right equipment for the job.
And you shouldn't even think of measuring the dc bridge voltage of your ups with this equipment.
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Why do everyone want to measure 50/60Hz mains with 100MHz scope? It is very dangerous and not very informative. What are you hoping to see? How seeing mains voltage would be useful? It is not much that you can do about mains quality anyway
If you are desperate, use handheld oscilloscope with properly rated probes. There are models like UNI-T UT81 series (crap 1 ch scope, but it will do very well for mains with DMM probes) or Hantek handhelds with isolated channels and 100x high voltage probes.
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Hi, dimitri we can talk about this before you break your brand new scope.
I think i am in your area, i need a scope too, perhaps you can direct me to the shop you got yours from?
Also step the mains voltage down using a transformer is best practice.
There are number of ways to drop the voltage down; however, only one offers isolation in addition to drop down.
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I don't think anybody actually answered the question on this thread.
YES you can connect it to the mains and you will see the AC sine wave.
(be careful about it, all it takes is a little mistake and you will get a big blow)
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dont do it without a 100:1 probe, even if you think you know what your doing.
the supplied probes maybe be rated for the voltage, but they have no headspace for the ripple or any surges/spikes.
we could be talking short spikes in the KV range.