High voltage probes for rectified 220v AC?

[tiagobaracho]

Hello tiagobaracho - the max. peak to peak input range is more important than the division ratio 10:100 - 700V or 20:200 - 1400V range. It depends upon what you intend to do later with these HV probes. As you probably know the rms value of the AC grid needs to be multiplied with root of 8 => 230V x 2.83 to obtain its peak to peak value 651Vpp: -325Vp - +325Vp.
The 700V version is safe for your current application, but might be marginal for future applications like qualification of SMPS ... - that is why I selected the HZ115/GE8115 which withstands 1.4kVpp. [HZ115 is a Hameg brand]
The low cost probe I was talking about is from PinTek - Taiwan, basic model DP-25 and DP-35 it is popular on eBAY - exact the same as what GWInstek is offering as GDP-025.

Make a search under Differential probe on following site:
http://www.pintek.com.tw/

Good luck !

I just bought one Pintek DP-25 here in my country.. should arrive in 7 days  for 326 USD with shipping....It does use one external power supply... but i guess i will do a 3s lipo battery with 7809 power regulator to use as a clean power supply for it, instead of using the power supply.... i guess this way i will have the best possible signal....
Actually.. i may test is it does make any difference.... , but i guess its even simpler to use the battery stick to the bottom of the probe box..

[Melkor]

Unfortunately the voltage spec is not enough to be sure you are safe with normal probes.
Check the CAT rating too. If your DUT is connected directly to mains you can get voltage spikes that are well beyond the nominal voltage.
I prefer to play on the safe side so I use a small 230V/12V transformer as I don't have resources for differential probes.
I don't think the shape of the signal is too far off. Probably depends on the frequency.

[tiagobaracho]

Unfortunately the voltage spec is not enough to be sure you are safe with normal probes.
Check the CAT rating too. If your DUT is connected directly to mains you can get voltage spikes that are well beyond the nominal voltage.
I prefer to play on the safe side so I use a small 230V/12V transformer as I don't have resources for differential probes.
I don't think the shape of the signal is too far off. Probably depends on the frequency.

You can only use this transformer on Ac , right? After rectifier i would not be able to use... And i guess it can change a bit some wave details, am i wrong ?

[PA4TIM]

Tiagobaracho, you do not need to quote every post, that makes the topic very hard to read.

I use an isolation transformer for every repair of instrument that are mains powered. I have Tek differential probes but they are not for high voltage use.
Your diff probe is 25 MHz or so but I do not think you will get it that high without ringing or other effects with multimeter like wires. But that is not a real problem for repairing SMPS.

[kg4arn]

Regarding Pintek,

Sapphire Instruments, who is as far as I am aware a reputable OEM of differential probes, claims that Pintek has copied their designs without permission.

http://www.sapphire.com.tw/notify.pdf

[Melkor]

You can only use this transformer on Ac , right? After rectifier i would not be able to use... And i guess it can change a bit some wave details, am i wrong ?

The waveform is good enough for me but you are right about the AC only part. Your application looks like a tricky one. For both safety and accuracy it seems that you will need a differential probe after all.

[lewis]

Sapphire Instruments, who is as far as I am aware a reputable OEM of differential probes, claims that Pintek has copied their designs without permission.

That's a bit worrying. With a bit of kit like this you need to trust it. The diff probe appears to be rated to 600V CAT III which means it can be used directly on domestic AC mains before the socket outlet, but not at the origin of the installation (electricity meter). Off the top of my head, CAT III overvoltage is 4kV, but don't quote me on that, I'd need to look it up.

I wouldn't use it in a CAT III environment though, but it should be fine in CAT II (after the socket outlet). Just be careful. More info here: http://en.wikipedia.org/wiki/Measurement_category

[jmcdonald]

How about Doug Fords design for a 1000:1 probe on EEV episode 85.

[tiagobaracho]

on tequipment they have Cal Test for 288 is you quote with them... i thinks  this should be the best price...i guess still have 6% of eevblog

[PA4TIM]

How about Doug Fords design for a 1000:1 probe on EEV episode 85.

A HV probe is not for mains connected measurements on the mains grid side. And most are only for multimeter use. (and the multimeter must match the probes resistance for the right reading, most need a 10M multimeter. I do not know the EEV episode 85 design)

Fordirect to mains connected measurements you need a diff porobe or 1:1 isolation transformer

[tiagobaracho]

Hi guys !! I received my DS2072A .. I AM IN LOVE !!!! my first scope and seems amazing... I bought the differential probe.. Still waiting for delivery...

I have one doubt...
I did one test here.... The pron has 3 pins right ..... I did test with adapter not connecting the earth pin...
On both positions,  ( live one side and ground on the other...vice and verse) when i touch on the ground of BNC i could fell a little bit of shock in my fingers...

This sometimes is common with few electronics device like computers, washing machine.... and if you plug it the other way, usually it stops..... So what i do is find this better position and then put the earth... ( usually the default position are the best)...
But on this rigol, i felt the shock on both position.... Is that normal ? Because i guess first without the ground it should be isolated the BNC ground to the mains input.... but if i am feeling small shock, it means that back on the power supply live part, there should be something going through both input wires to the ground...
This is the power supply from the teardown dave did... Look the C149 and C150 capacitors
http://www.flickr.com/photos/eevblog/8022086942/#in/set-72157631618295437
Both are connected to one side of the input and the other side goes to ground... So if ground is floating(not connected), the live wire( does not matter wich pins is it) will go through a capacitor and to the ground... I suppose that if I remove those caps the shock on the ground  would go away.
Look the picture i took just touch the probe ... It shows the 60  HZ signal from the 220v outlet because in reference to the scope BNC ground i am real earth ground and the scope ground is transmitting some of the input live...
its normal and the power supply needs the earth to work well ??
Thanks

[BravoV]

I received my DS2072A .. ....my first scope and seems amazing

. I bought the differential probe.. Still waiting for delivery...

On both positions,  ( live one side and ground on the other...vice and verse) when i touch on the ground of BNC i could fell a little bit of shock in my fingers...

But on this rigol, i felt the shock on both position.... Is that normal ?

... i guess .....

i am feeling small shock

Both are connected to one side of the input and the other side goes to ground... So if ground is floating(not connected), the live wire( does not matter wich pins is it) will go through a capacitor and to the ground... I suppose that if I remove those caps the shock on the ground  would go away.

It shows the 60  HZ signal from the 220v outlet because in reference to the scope BNC ground i am real earth ground and the scope ground is transmitting some of the input live...

  ... just becareful !!!

Expecting next post ..... HELP !!!! My new scope is toasted !!!!! .... or .... no new post will be posted again, ever.

[tiagobaracho]

Thanks for your reply, but i am not stupid ... I have been fixing for 13 years, and is not now that I will need this kind of beginner advice...

[granz]

This sometimes is common with few electronics device like computers, washing machine.... and if you plug it the other way, usually it stops..... So what i do is find this better position and then put the earth... ( usually the default position are the best)...

Both are connected to one side of the input and the other side goes to ground... So if ground is floating(not connected), the live wire( does not matter wich pins is it) will go through a capacitor and to the ground... I suppose that if I remove those caps the shock on the ground  would go away.

Look the picture i took just touch the probe ... It shows the 60  HZ signal from the 220v outlet because in reference to the scope BNC ground i am real earth ground and the scope ground is transmitting some of the input live...
its normal and the power supply needs the earth to work well ??
Thanks

What country are you in where they use 220v/60Hz ?  That's fairly uncommon.  (Peru?)  Also, if you are swapping hot/neutral by flipping the plug around it sounds like you don't have polarized outlets...  You should really replace these with newer polarized ones, or at least re-wire them to always have hot and neutral on the same sides.

Yes, you do want the ground connected for a few reasons.  Those two caps on the input form part of the EMI filter, and when you remove the ground connection you reduce the effectiveness of that filter, allowing more noise in (and out).  Besides that, it really is a safety hazard to leave the ground disconnected, especially on a scope.  Consider what happens when one of those input caps fails shorted: the BNC ground is now live as well as anything you have connect to the scope probe ground lead.

[hibone]

Hi everyone.
I was wondering if any of the high voltage (differential) probes, available on the market, also provides galvanic isolation of the output from the input.

Thank you.