I use differential probes because of three advantages. First is skew. Second is noise. Third is input count. You can deskew probes, but as your “super tech” was probably fighting, the skew is relative to frequency and the complex input impedance of the scope. Once the single-ended probes are deskewed, they have to stay with the input they are connected to. Because the scope input is a complex impedance, everything is always different in delay (length) and coax impedances that change with flexing, and probe compensation circuits are also complex impedances, the waveforms end up getting distorted over a wideband (think GHz) signals. Differential probes put the matching problem right down at the DUT and isolate all of the coax and scope effects from the measurement. The matching and calibration is built into the differential probe and the probe can be compensated over frequency without scope and coax effects. Second, the noise induction on differential probes is at the tip. As you noted in the video, two single-ended probes have a “ground loop” (I hate that term). The separate grounds pick up separate noise that will common mode couple into each single-ended connection, which creates a differential noise into the system. A differential probe pushes all down to the DUT end of the system, so there is less chance of noise coupling in. The differential probes save inputs on the scope. Scopes more than four inputs get expensive fast as ports are added. With four inputs a scope is reduced to being effectively two input when the scope is doing the differential work. I find that I often need a third input, where the other two are differential. Unless I use a differential probe or two, my scopes won’t have enough inputs. Thanks for the review of this differential probe. I always like to hear what is new and might make things better or easier. 100MHz is not overly useful for me, but if a good value it will find some use. I hate using $2000 probes on high voltage circuits where they might get damaged, so maybe the probe you have here is a better choice for the applications you noted. Thanks again for these great videos!
Galvanic isolation Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow; no direct conduction path is permitted. Energy or information can still be exchanged between the sections by other means, such as capacitive, inductive, radiative, optical, acoustic, or mechanical coupling. Galvanic isolation is used where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor. Galvanic isolation is also used for safety, preventing accidental electric shocks. Wikipedia ...always learning. Great video, keep them coming.
Sweet test equipment. Our factory uses lots of 3 phase 440vac VFD AC motor drives and 250hp DC motor drives. The Fluke 2-channel 190 scope is the 1st choice to troubleshoot these motor drives. However, these differential probes seem promising with non-isolated bench scopes. Also, 440vac electric fork truck battery charger inverters are becoming a big concern. Some are creating dirty electricity with unwanted harmonics and messing up the power factor with Apparent Power. 😎 Thank you for the probe overview.
What I'd love to see is a shootout of HVDPs at KHz frequencies. Not every diff probe is used for high freq power supplies... For a current project I'm working with "large" coils operating in the 6-12 Khz range (if repeated) for 1 TC. I was thinking of getting the older Micsig DP10007 until I saw Dave's review with the horrible characteristics it has at those frequencies. If these things have a similar front end as the fiber probe version, they might be a better choice than the older HVP-70 style probes as the MDP700 isn't much more.
Thanks for your feedback. I like the DP10007;) Are you referring to the CMRR test that Dave did? I think he was trying to find a reason for his probe to cost so much more:) I've been planning to do a shoot out between the different Diff Probes that I have. I'll have to do this soon. I started to do it awhile back but the footage was ruined and then I had moved on to another project;)
@@KissAnalog Yes that test. His results looked absolutely horrible at that range. The newer MDP* versions might fare a bit better, but who knows without testing.
@@KissAnalog Really well designed. Putting the 5 mhz filter on the probe was a really good idea. I also like the relatively small size - but it is very solid. Having the case is another plus since I won't be using it all the time. Yeah, I would buy it again.
The probes are so short because they are banana plugs and they likely expect YOU to get the wire extensions- depending on how long you need them to be. I'm fairly sure that they're not intended to be used right there next to the box like that. :).. Most of us have different length banana plug extensions lying around, so I can understand why they didn't include any.. Although a 3ft set would have been reasonable.
@@KissAnalog I was troubleshooting an arcade game in the 90’s that had a motor speed control because it made the seats move, and our scope cart didn’t have an isolation transformer. I think the ground wires on the probe melted and the scope was sent to Tektronix for repair. Might have been both channels. I have an isolation scope probe now.
I use differential probes because of three advantages. First is skew. Second is noise. Third is input count.
You can deskew probes, but as your “super tech” was probably fighting, the skew is relative to frequency and the complex input impedance of the scope. Once the single-ended probes are deskewed, they have to stay with the input they are connected to. Because the scope input is a complex impedance, everything is always different in delay (length) and coax impedances that change with flexing, and probe compensation circuits are also complex impedances, the waveforms end up getting distorted over a wideband (think GHz) signals. Differential probes put the matching problem right down at the DUT and isolate all of the coax and scope effects from the measurement. The matching and calibration is built into the differential probe and the probe can be compensated over frequency without scope and coax effects.
Second, the noise induction on differential probes is at the tip. As you noted in the video, two single-ended probes have a “ground loop” (I hate that term). The separate grounds pick up separate noise that will common mode couple into each single-ended connection, which creates a differential noise into the system. A differential probe pushes all down to the DUT end of the system, so there is less chance of noise coupling in.
The differential probes save inputs on the scope. Scopes more than four inputs get expensive fast as ports are added. With four inputs a scope is reduced to being effectively two input when the scope is doing the differential work. I find that I often need a third input, where the other two are differential. Unless I use a differential probe or two, my scopes won’t have enough inputs.
Thanks for the review of this differential probe. I always like to hear what is new and might make things better or easier. 100MHz is not overly useful for me, but if a good value it will find some use. I hate using $2000 probes on high voltage circuits where they might get damaged, so maybe the probe you have here is a better choice for the applications you noted.
Thanks again for these great videos!
HI Eddie, I really enjoy your content and intelligent comments from your viewers, thank you. 😁
Galvanic isolation
Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow; no direct conduction path is permitted. Energy or information can still be exchanged between the sections by other means, such as capacitive, inductive, radiative, optical, acoustic, or mechanical coupling. Galvanic isolation is used where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor. Galvanic isolation is also used for safety, preventing accidental electric shocks. Wikipedia
...always learning.
Great video, keep them coming.
Sweet test equipment. Our factory uses lots of 3 phase 440vac VFD AC motor drives and 250hp DC motor drives. The Fluke 2-channel 190 scope is the 1st choice to troubleshoot these motor drives. However, these differential probes seem promising with non-isolated bench scopes. Also, 440vac electric fork truck battery charger inverters are becoming a big concern. Some are creating dirty electricity with unwanted harmonics and messing up the power factor with Apparent Power. 😎 Thank you for the probe overview.
Thanks for the great real world applications;)
Thanks!
Thank you so much! I appreciate you!
What I'd love to see is a shootout of HVDPs at KHz frequencies. Not every diff probe is used for high freq power supplies...
For a current project I'm working with "large" coils operating in the 6-12 Khz range (if repeated) for 1 TC. I was thinking of getting the older Micsig DP10007 until I saw Dave's review with the horrible characteristics it has at those frequencies. If these things have a similar front end as the fiber probe version, they might be a better choice than the older HVP-70 style probes as the MDP700 isn't much more.
Thanks for your feedback. I like the DP10007;) Are you referring to the CMRR test that Dave did? I think he was trying to find a reason for his probe to cost so much more:) I've been planning to do a shoot out between the different Diff Probes that I have. I'll have to do this soon. I started to do it awhile back but the footage was ruined and then I had moved on to another project;)
@@KissAnalog Yes that test. His results looked absolutely horrible at that range. The newer MDP* versions might fare a bit better, but who knows without testing.
Great info, and refresher for me, thanks for sharing.
You bet! Thanks for your feedback!
I just received my 1502 probe (4/29/2024) and it came with a plastic case.
Wow - how do you like the probe? Here's a link for anyone else;) amzn.to/3UgNjlA
@@KissAnalog Really well designed. Putting the 5 mhz filter on the probe was a really good idea. I also like the relatively small size - but it is very solid. Having the case is another plus since I won't be using it all the time. Yeah, I would buy it again.
The probes are so short because they are banana plugs and they likely expect YOU to get the wire extensions- depending on how long you need them to be. I'm fairly sure that they're not intended to be used right there next to the box like that. :).. Most of us have different length banana plug extensions lying around, so I can understand why they didn't include any.. Although a 3ft set would have been reasonable.
Thanks for your feedback! For me - I love the short length. For people that need a bit more length they can do what they want for length.
❤❤❤❤
Thank you!
Sir What is the cost of these differential prob and make?
I have blown up a scope before
Thanks for sharing that! I think it happens more often than we want to admit. Did it just kill one channel, or did it do more damage?
@@KissAnalog I was troubleshooting an arcade game in the 90’s that had a motor speed control because it made the seats move, and our scope cart didn’t have an isolation transformer. I think the ground wires on the probe melted and the scope was sent to Tektronix for repair. Might have been both channels. I have an isolation scope probe now.
Wow - that can be tricky without a differential probe or isolated input channels.