Author Topic: what an oscilloscope recommended for a woman passionate about electronics?  (Read 144276 times)

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Offline tggzzz

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this would only happen if I was wrong to position the ground clip. If the clip is positioned exactly on the circuit ground, then with the 1x10 probe would it be possible to measure 230vrsm? (I won't do it)

a curiosity: ok even with 1x10 probe better not to measure the mains voltage. But reasonably, up to what voltage limit of the circuit is it possible to measure safely with the oscilloscope using normal and non-voltage probes? 30, 60 volts max?
My Hantek probes are rated 600V peak in 10x mode and 200V in 1x mode. 230VRMS is easily within their capability in 10x mode.

It's not about voltage, it's about transient overvoltages and available pulse energy in the event the probe's insulation breaks down and arcs over. Same applies to DMM and their probes.
https://content.fluke.com/promotions/promo-dmm/0518-dmm-campaign/dmm/fluke_dmm-chfr/files/safetyguidelines.pdf

Most simple scope probes simply aren't CAT rated at all. They may work, until some motor turns off nearby and then they may or may not crap out, no warranty.

It is worth looking at the voltage rating as a function of frequency. You will probably be surprised at the low voltages and frequencies involved.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline CharlotteSwissTopic starter

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You can use Siglent's ISFE albeit with limited BW.
These connect directly to the scopes input BNC's and provide for 2 isolated channels.
https://www.siglenteu.com/accessory/isolated-channel-optional-accessories%ef%bc%88isfe%ef%bc%89/
interesting, and with this device can I also measure the mains voltage safely? But it would be fantastic ...
 ;)
thanks
 

Offline CharlotteSwissTopic starter

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It's always worth checking the probe compensation, it only takes a moment to do it.

ok, so it would be better to do it every time you use the oscilloscope .. it doesn't hurt so much
 ;)
 

Offline CharlotteSwissTopic starter

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My Hantek probes are rated 600V peak in 10x mode and 200V in 1x mode. 230VRMS is easily within their capability in 10x mode.

It's not about voltage, it's about transient overvoltages and available pulse energy in the event the probe's insulation breaks down and arcs over. Same applies to DMM and their probes.
https://content.fluke.com/promotions/promo-dmm/0518-dmm-campaign/dmm/fluke_dmm-chfr/files/safetyguidelines.pdf

Most simple scope probes simply aren't CAT rated at all. They may work, until some motor turns off nearby and then they may or may not crap out, no warranty.

so if I understand correctly, you can measure the 230rsm network voltage by setting the probes to 1x10. The danger comes only if the ground probe is wrong. Correct?
perhaps for a beginner like me better not to risk...
 ???
 

Offline CharlotteSwissTopic starter

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I just took it out of the box, everything perfect, thanks Siglent  8)
I see some pink on the control of channel 2, they thought of me when they designed it  ;D
Today maybe I can only turn it on, from tomorrow I'll do some tests ...
 ^-^

 
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Offline rstofer

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so if I understand correctly, you can measure the 230rsm network voltage by setting the probes to 1x10. The danger comes only if the ground probe is wrong. Correct?
perhaps for a beginner like me better not to risk...
 ???

You have been warned by some very experienced people not to measure mains voltage.  That somebody gave you a procedure that MIGHT work (I didn't check it), it comes with a certain risk of having exposed voltages where you don't want them.  Like on the BNC connectors... As soon as you see the phrase 'float the scope', run away fast!  The term "isolation transformer" isn't much better.  Please don't do it! 

Even if you saw all the trash in the world on the mains, you a) couldn't do anything about it and b) prove that it caused any harm.  There is just no valid reason for probing mains at your level of experience.  I say that because I have been fooling around with this stuff for over 60 years and I don't have a reason for doing it and never have.  The only good thing to come from probing mains is to increase the sales of scopes.

Once you learn about differential measurements and differential probes then, given adequate Personal Protective Equipment (PPE), go for it!  Until then, stay on the low voltage side of power sources.  Even then, you have to know what you're doing before you hook up that ground lead.

I'm not even a fan of the A-B method of taking a differential measurement with 2 channels.  In this case, both ground clips are physically removed from the probes and two probes are used to take the measurement. You can read up on differential measurements but I still wouldn't recommend it.

Which brings up another problem.  Even if the probes are rated for the voltage, the scope probably isn't.  So we use 10x probes.  But that's a trap when it is just a slide switch selecting 1x or 10x.  It is inevitable that Murphy will have the switch in the wrong position.  If you need 10x probes, buy fixed 10x probes with no switches.  Probe Master makes some as does every other probe manufacturer.

Please stay away from mains!
« Last Edit: September 25, 2020, 04:55:09 am by rstofer »
 

Offline dietert1

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Another hint for a beginner: The ground clip of a scope probe always wants to fall into the live circuit and make a short. Better take it off and keep it in a safe place. It is needed only for high frequency measurements above some MHz and even then it isn't ideal. If the device to be repaired needs grounding, do that first before starting to make a measurement.

Regards, Dieter
 

Offline ArthurDent

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There has been more back and forth on probe compensation than needed.

The first thing I’d do is make sure the probes are identified for channel 1 (yellow) and channel 2 (pink) by having the small plastic colored split rings on the corresponding probes. Then follow the simple procedure in the manual to adjust the compensation with the test signal. This step only has to be done once as long as you don’t switch or replace probes.

The reason to follow this procedure and not switch probes between channels is that there are minor differences between channels so if you switch probes, the differences between channels and probes could really affect how the signal you’re measuring will be measured and shown on the screen.

The reason a 1 Khz square wave signal can be used to compensate a probe for 200 Mhz is that a square wave can be thought of as a sine wave of infinite frequency and if you can display the test 1 Khz square wave properly the scope will display other waveforms within its bandwidth properly as well. A 1 Khz test sine wave just wouldn’t work for compensation purposes. 

Here’s a short Siglent video that does a better job of explaining than I have.


 

Offline CharlotteSwissTopic starter

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You have been warned by some very experienced people not to measure mains voltage.  That somebody gave you a procedure that MIGHT work (I didn't check it), it comes with a certain risk of having exposed voltages where you don't want them.  Like on the BNC connectors... As soon as you see the phrase 'float the scope', run away fast!  The term "isolation transformer" isn't much better.  Please don't do it! 
Once you learn about differential measurements and differential probes then, given adequate Personal Protective Equipment (PPE), go for it!  Until then, stay on the low voltage side of power sources.  Even then, you have to know what you're doing before you hook up that ground lead.
Which brings up another problem.  Even if the probes are rated for the voltage, the scope probably isn't.  So we use 10x probes.  But that's a trap when it is just a slide switch selecting 1x or 10x.  It is inevitable that Murphy will have the switch in the wrong position.  If you need 10x probes, buy fixed 10x probes with no switches.  Probe Master makes some as does every other probe manufacturer.
Please stay away from mains!

attention rstofer: I only asked out of curiosity, I have already said several times that I will measure with the oscilloscope only on the BT circuit parts (no mains voltage for my measurements).
I noticed with pleasure that the chassis is all non-conductive (terminals excluded ..)
I have to be very careful when placing the ground probe on a zero voltage part of the circuit ... If it is positioned where there is voltage, everything becomes dangerous ...
 ;)
 

Offline CharlotteSwissTopic starter

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Another hint for a beginner: The ground clip of a scope probe always wants to fall into the live circuit and make a short. Better take it off and keep it in a safe place. It is needed only for high frequency measurements above some MHz and even then it isn't ideal. If the device to be repaired needs grounding, do that first before starting to make a measurement.
Regards, Dieter

 :-/O I'm so beginner that I didn't understand this warning. But I guess it's very important to understand
 :-[
 

Offline CharlotteSwissTopic starter

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There has been more back and forth on probe compensation than needed.
The first thing I’d do is make sure the probes are identified for channel 1 (yellow) and channel 2 (pink) by having the small plastic colored split rings on the corresponding probes. Then follow the simple procedure in the manual to adjust the compensation with the test signal. This step only has to be done once as long as you don’t switch or replace probes.
The reason to follow this procedure and not switch probes between channels is that there are minor differences between channels so if you switch probes, the differences between channels and probes could really affect how the signal you’re measuring will be measured and shown on the screen.

so, always using the same probes and each always in the same channel, could it be enough to calibrate the first time and that's it?
My two probes both have the yellow ring ... but I see that in the small parts there are many colored rings, then to a probe I remove the yellow ones and I put the pink ones



 8)
 

Offline ArthurDent

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There has been more back and forth on probe compensation than needed.
The first thing I’d do is make sure the probes are identified for channel 1 (yellow) and channel 2 (pink) by having the small plastic colored split rings on the corresponding probes. Then follow the simple procedure in the manual to adjust the compensation with the test signal. This step only has to be done once as long as you don’t switch or replace probes.
The reason to follow this procedure and not switch probes between channels is that there are minor differences between channels so if you switch probes, the differences between channels and probes could really affect how the signal you’re measuring will be measured and shown on the screen.

so, always using the same probes and each always in the same channel, could it be enough to calibrate the first time and that's it?
My two probes both have the yellow ring ... but I see that in the small parts there are many colored rings, then to a probe I remove the yellow ones and I put the pink ones



 8)

Yes. remove one set of yellow split rings and replace them with the pink ones and calibrate both probes once and don't switch probes between channels. Think of them as left and right shoes. If you put them on the correct foot, they work great; if you put them on the opposite foot-not so great.  ;D

You might want to check the probes compensation every few months just to verify that they are still properly compensated and until you become confident they are staying in cal. 
 

Offline tggzzz

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My Hantek probes are rated 600V peak in 10x mode and 200V in 1x mode. 230VRMS is easily within their capability in 10x mode.

It's not about voltage, it's about transient overvoltages and available pulse energy in the event the probe's insulation breaks down and arcs over. Same applies to DMM and their probes.
https://content.fluke.com/promotions/promo-dmm/0518-dmm-campaign/dmm/fluke_dmm-chfr/files/safetyguidelines.pdf

Most simple scope probes simply aren't CAT rated at all. They may work, until some motor turns off nearby and then they may or may not crap out, no warranty.

so if I understand correctly, you can measure the 230rsm network voltage by setting the probes to 1x10. The danger comes only if the ground probe is wrong. Correct?
perhaps for a beginner like me better not to risk...
 ???

Not just a beginner; even experienced people that take precautions have killed themselves.

I've given a link to the relevant posting of mine in one of my earlier messages.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline tggzzz

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You can use Siglent's ISFE albeit with limited BW.
These connect directly to the scopes input BNC's and provide for 2 isolated channels.
https://www.siglenteu.com/accessory/isolated-channel-optional-accessories%ef%bc%88isfe%ef%bc%89/
interesting, and with this device can I also measure the mains voltage safely? But it would be fantastic ...
 ;)
thanks

I don't understand what that device does and does not guarantee. P6 and 7 of the instruction manual makes me go "Uh oh, what's happening here, that sounds wrong and/or dangerous".
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline tggzzz

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so if I understand correctly, you can measure the 230rsm network voltage by setting the probes to 1x10. The danger comes only if the ground probe is wrong. Correct?
perhaps for a beginner like me better not to risk...
 ???

You have been warned by some very experienced people not to measure mains voltage.  That somebody gave you a procedure that MIGHT work (I didn't check it), it comes with a certain risk of having exposed voltages where you don't want them.  Like on the BNC connectors... As soon as you see the phrase 'float the scope', run away fast!  The term "isolation transformer" isn't much better.  Please don't do it! 

Even if you saw all the trash in the world on the mains, you a) couldn't do anything about it and b) prove that it caused any harm.  There is just no valid reason for probing mains at your level of experience.  I say that because I have been fooling around with this stuff for over 60 years and I don't have a reason for doing it and never have.  The only good thing to come from probing mains is to increase the sales of scopes.

Once you learn about differential measurements and differential probes then, given adequate Personal Protective Equipment (PPE), go for it!  Until then, stay on the low voltage side of power sources.  Even then, you have to know what you're doing before you hook up that ground lead.

I'm not even a fan of the X-Y method of taking a differential measurement with 2 channels.  In this case, both ground clips are physically removed from the probes and two probes are used to take the measurement. You can read up on differential measurements but I still wouldn't recommend it.

Which brings up another problem.  Even if the probes are rated for the voltage, the scope probably isn't.  So we use 10x probes.  But that's a trap when it is just a slide switch selecting 1x or 10x.  It is inevitable that Murphy will have the switch in the wrong position.  If you need 10x probes, buy fixed 10x probes with no switches.  Probe Master makes some as does every other probe manufacturer.

Please stay away from mains!

Seconded. Repeated here for emphasis.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline dietert1

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Another hint for a beginner: The ground clip of a scope probe always wants to fall into the live circuit and make a short. Better take it off and keep it in a safe place. It is needed only for high frequency measurements above some MHz and even then it isn't ideal. If the device to be repaired needs grounding, do that first before starting to make a measurement.
Regards, Dieter

 :-/O I'm so beginner that I didn't understand this warning. But I guess it's very important to understand
 :-[

The ground clip is the short wire on the side of the probe with blank metal visible ("crocodile clip"). It is meant to be connected to the reference level/Gnd of the circuit you want to analyze. But if you forget to connect it or it falls off or you tear it off accidentally, you have a good chance the blank metal will touch somewhere where it should not and make a short to protective ground. And you destroyed the circuit you wanted to measure.

With a little force you can pull that wire with the clip away from the probe, to avoid that risk of making a short. Keep it in safe place, you may need it later.

Now, to make a measurement, the reference level/Gnd of the circuit you want to measure needs to be connected to protective ground. If it isn't you have to make a connection with a wire/cable. That connection will then replace the Gnd clip of the probe that you took off.

The only other blank metal on the probe is the small probe tip and that is high impedance and meant to be connected to the test point.

Regards, Dieter

 

Offline rstofer

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You can use Siglent's ISFE albeit with limited BW.
These connect directly to the scopes input BNC's and provide for 2 isolated channels.
https://www.siglenteu.com/accessory/isolated-channel-optional-accessories%ef%bc%88isfe%ef%bc%89/
interesting, and with this device can I also measure the mains voltage safely? But it would be fantastic ...
 ;)
thanks
  I''''''''''
I don't understand what that device does and does not guarantee. P6 and 7 of the instruction manual makes me go "Uh oh, what's happening here, that sounds wrong and/or dangerous".

I didn't understand it either!  Especially the admonition to avoid touching the BNC connectors on the scope when the device is in use.  Furthermore, I'm not entirely certain I want to use the scope's USB port to power a differential <whatever it is>.
 

Offline magic

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I suppose they mean that if the dongle is not plugged into a scope, high potential may appear on the output ground (hopefully at high impedance, but still). Or maybe at low impedance, who knows >:D

Much funnier is page 4. Somehow they managed to get every single one of those wrong :clap:
 

Online tautech

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The OP has no doubt compensated her probes already but I'll add for other followers.

While using Autoset is simple and comforting for new DSO users it's also good to know how drive the scope with intent.

This is the setup I use when checking each scope and compensating probes before dispatch.
Compensate ch1 probe first then reduce vertical sensitivity while compensating ch2.
Pic added as a thumbnail to the post to show the OP that an image hosting site is not required.



Another look at compensating probes is how Defpom does it.
Avid Rabid Hobbyist.
Some stuff seen @ Siglent HQ cannot be shared.
 

Offline CharlotteSwissTopic starter

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Yes. remove one set of yellow split rings and replace them with the pink ones and calibrate both probes once and don't switch probes between channels. Think of them as left and right shoes. If you put them on the correct foot, they work great; if you put them on the opposite foot-not so great.  ;D

You might want to check the probes compensation every few months just to verify that they are still properly compensated and until you become confident they are staying in cal.

it will be impossible to invert probes, I leave them fixed to the two channels...
or maybe when I only use one it would be better not to have connected the other probe?  :o
thanks  ;)
 

Offline 0culus

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You can use Siglent's ISFE albeit with limited BW.
These connect directly to the scopes input BNC's and provide for 2 isolated channels.
https://www.siglenteu.com/accessory/isolated-channel-optional-accessories%ef%bc%88isfe%ef%bc%89/
interesting, and with this device can I also measure the mains voltage safely? But it would be fantastic ...
 ;)
thanks

I don't understand what that device does and does not guarantee. P6 and 7 of the instruction manual makes me go "Uh oh, what's happening here, that sounds wrong and/or dangerous".

 :wtf:

A proper HV differential probe should be preferred, not that piece of junk...even a Keysight branded one that is good to 50 MHz or so isn't that expensive.

To the OP: I strongly recommend leaving high voltage and mains side stuff alone until you have a lot more experience. Just don't do it. Stick with low voltage circuits powered by at most a low voltage DC bench power supply for now and focus on understanding how to use your new scope. You have to be careful enough probing low voltage stuff just to ensure you're getting good measurements. When you move to higher energy circuits, you have to be a million times more careful, and even so experienced people have blown up test equipment at best and gotten killed at worst.

 

Offline CharlotteSwissTopic starter

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Not just a beginner; even experienced people that take precautions have killed themselves.

I've given a link to the relevant posting of mine in one of my earlier messages.

 ::) ::) ::)
now that I have the oscilloscope ready, I am discovering that it is a highly dangerous instrument; I'm worried
 :-[ :-[ :-[ :-[
 

Offline CharlotteSwissTopic starter

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I don't understand what that device does and does not guarantee. P6 and 7 of the instruction manual makes me go "Uh oh, what's happening here, that sounds wrong and/or dangerous".

tggzzz, I often struggle to follow your speech  :-\ (but I guess it's my english translator's fault)
 

Offline CharlotteSwissTopic starter

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The ground clip is the short wire on the side of the probe with blank metal visible ("crocodile clip"). It is meant to be connected to the reference level/Gnd of the circuit you want to analyze. But if you forget to connect it or it falls off or you tear it off accidentally, you have a good chance the blank metal will touch somewhere where it should not and make a short to protective ground. And you destroyed the circuit you wanted to measure.

With a little force you can pull that wire with the clip away from the probe, to avoid that risk of making a short. Keep it in safe place, you may need it later.

Now, to make a measurement, the reference level/Gnd of the circuit you want to measure needs to be connected to protective ground. If it isn't you have to make a connection with a wire/cable. That connection will then replace the Gnd clip of the probe that you took off.

The only other blank metal on the probe is the small probe tip and that is high impedance and meant to be connected to the test point.

ok, now I understand the problem: the ground probe could come off and go to a point in tension, causing big problems.
so you suggested that it would be better to remove the piece that acts as the ground from the probe ...
But I don't understand what alternative to use to connect the probe to the ground!
thanks  ;)
 

Offline CharlotteSwissTopic starter

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The OP has no doubt compensated her probes already but I'll add for other followers.

Pic added as a thumbnail to the post to show the OP that an image hosting site is not required.


but OP who would it be?
I don't know how to insert photos in any other way
 ;)
« Last Edit: June 27, 2020, 06:39:41 am by CharlotteSwiss »
 


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