Teledyne LeCroy WaveRunner 64xi, morphed to differential probes...

[joeqsmith]

Anyone who has ever made a wide band (DC to >1MHz), 10,000:1, >30KV probe and actually gotten it to work, my hats off to you!   

What a nightmare of a project. 

[tautech]

What a nightmare of a project.

And we were so sure you had it sorted. 

Keep up the great work Joe. 

[Mark_O]

I'm interested in the development of the new probe, but fail to see what it has to do with the Waverunner.

I just wish this had been split off as a separate topic, when the discussion branched.  Of course, since the guy doing the thread-diversion was the OP, I guess that's his right. 

But no one interested in wide-band HV probe construction will know it is buried in a wr64xi thread.    And others interested in the Waverunner, may not be interested in the probe.  So it doesn't seem to be serving either audience very well.   

[joeqsmith]

Finally, I have added the protection to the probe in case of a breakdown and dared to hook it to the DSO....   2KV 100us per division.  The transient that took out the 87V.   

The neon sign transformer leaks too much use it with the grounded scope.   

[Mark_O]

Maybe it's just me, but I'm getting a 0 byte file in Tran1.jpg.

[tautech]

Finally, I have added the protection to the probe in case of a breakdown and dared to hook it to the DSO....   2KV 100us per division.  The transient that took out the 87V.   

The Red Devil is back. 

[joeqsmith]

Finally, I have added the protection to the probe in case of a breakdown and dared to hook it to the DSO....   2KV 100us per division.  The transient that took out the 87V.   

The Red Devil is back. 

Too bad Fluke doesn't have a friend for her to play with 

[joeqsmith]

I've made some progress on my home made 10,000X high voltage probe.   This video shows how the probe is compensated.  It's then compared with my Tektronix P6013A.  Like the Northstar probes, all of the compensation networks are built into the probe.   I ended up shortening the coax cable to about 16 feet.     Also shown is some more details on the construction.     

During the video you may notice the MOVs and GDTs.  There is also a faster set of clamps as well to protect the DSO in case the probe were to arc over.   

https://www.youtube.com/watch?v=2SZyn2IMn9g&feature=youtu.be

[joeqsmith]

Waiting for the camera to charge up.....

The last test I want to run on the probe is to check the breakdown voltage.   So far for high voltage testing I have had it connected to the homemade transient generator and the neon sign transformer.   These don't put out any where near the what the probe should handle.   

A friend of mine who is a mechanic gave me a car ignition coil that has an isolated output.  He claims this is a hotter version of the coil.   I am not sure how much we can expect to get out of it.    I plan to put the probe on the output and just drive the thing into a spark gap and increase the gap until the probe breaks down or the coil does.

I'll sketch up a little schematic for it and go over that as well for those interested. 

[tautech]

I'll sketch up a little schematic for it and go over that as well for those interested.

I've got my hand up. 

[joeqsmith]

Played with spark gaps and corona dope most of the day.   The LeCroy still lives but it sure didn't like what I was putting it through today.   When your scope's LCD flickers and the mouse won't stay running, your doing something right.   

The video starts out comparing some basic schematics for probes then I go over the design for this probe.  After this, I show the car ignition coil setup which is very crude and then proceed to attempt to damage the probe with it.   

Keep in mind that the stub is critical just like it was with shell case probes.  I did not provide values in the schematics as I assume anyone attempting to replicate it would need to come up with their own compensation. 

[tautech]

Thanks Joe, very entertaining. 
65 KV is a great effort, but being able to safely measure it, mind blowing. 

[joeqsmith]

Thanks Joe, very entertaining. 
65 KV is a great effort, but being able to safely measure it, mind blowing. 

Thanks!   Glad you enjoyed them. 

The ignition coils don't produce enough energy that I get too concerned when using them.   The transorb I am currently using clamps around 7 volts, limiting the probe to 70KV.   The old LeCroy was having problems and I was already near the 70KV limit so I stopped.   

Thinking about the handle, I am considering making it all from metal and having a bell similar to the North Star PVM-3. 

http://www.highvoltageprobes.com/

Currently everything is out in the open and even without a shield over this area it still works pretty good.  It may end up being plastic.   Need to give it some more thought.   

[joeqsmith]

After some thought, here's what I came up with...

I stole the ground strap idea from the Tektronix P6013A and machined a slot for a small press contact that slides in the outside insulator.   This keeps the return path away from handle side. 

Next is the new handle next to the prototype one.   The handle is held on with a large nut that threads on the back of the BNC.   It's only ground is to the BNC.

Next is the Teflon insulator that holds the handle and the compensation network.   

[joeqsmith]

Here is the finished probe.  The dot in the insulator is one of three set screws that holds the handle in place.     The LeCroy is showing a PP002 probe (red) against the 10,000X probe (yellow) looking at the rising edge from my HP33120A ARB at 20nS/div.   I also ran some tests with a high voltage DC power supply today using the Fluke 101 (just in case something went wrong).   

[joeqsmith]

The last video I made showing the completed high voltage probe on the low frequency network analyzer and then compared with a LeCroy PP002A 350MHz 10X probe.   I finish up with the probe on a high voltage Spellman supply.   

The parts to build it were in the order of $100.

[joeqsmith]

I was cleaning out some of my crap and noticed a transformer from Austin transformers.   It's in a cylindrical metal can, sealed with solder and ceramic insulators.   It was rated for 50/60Hz and is made for isolation.   Playing around with it and it seems to have a BW in the 200KHz range.   

No idea what this thing was for but thinking to use it to make some sort of AC line power monitor probe for the old LeCroy.  Really don't have much of a need for something like this at home but seems like a simple project.   Noticed Teledyne/LeCroy offers some sort of package but I have played with it.

http://cdn.teledynelecroy.com/files/pdf/power_analyzer_datasheet.pdf 

My plan is to use this isolation transformer and a LEM sensor (also good to about 200KHz) and just post post process the data with a PC.   

[rsjsouza]

Joe, excellent job on this probe. I was wondering about the voltage spikes messing with the oscilloscope and seeing your Picture I thought about a thread that mentioned BNC caps (or dust covers). The ones you are using seem to be yellow plastic, but perhaps an all-metal one that physically grounds the input may be worth trying, what do you think?

The post that references this is below:
https://www.eevblog.com/forum/testgear/siglent-they-filed-a-'wrongful-trademark-claim'/msg786287/#msg786287

Also, someone else sent a link to an eBay listing for a more reasonable quantity:
https://www.eevblog.com/forum/testgear/siglent-they-filed-a-'wrongful-trademark-claim'/msg786701/#msg786701

(edit: fixed link)

[joeqsmith]

Thanks.   I have been pretty happy with all the home made probes.   

The Caplugs covers are there to prevent mechanical damage to the connectors.  Like keeping my grubby oily hands off them.    I would imagine that most scopes inputs are fairly protected electrically.   Maybe not the bottom basement ones for cost reasons.      

Those ignition systems can sure make a lot of noise.   I would guess my PC was about 6 feet from that jig and the USB mouse on the PC was hung after test and needed to be power cycled.   This is pretty common problem with USB. It's not a robust bus.   I suspect on the LeCroy that the noise was causing the LCD interface to get corrupt.   Beyond the LCD and the mouse shutting down, there were no other problems.   

[joeqsmith]

The completed power monitor adapter.   The CB has a 10A trip current and the LEM is set for about 8 Amps.   Software is mostly done.  Calculates the basic stuff.   

I'll put together some sort of demo for it.   

[rsjsouza]

Thanks.   I have been pretty happy with all the home made probes.   

The Caplugs covers are there to prevent mechanical damage to the connectors.  Like keeping my grubby oily hands off them.    I would imagine that most scopes inputs are fairly protected electrically.   Maybe not the bottom basement ones for cost reasons.      

Those ignition systems can sure make a lot of noise.   I would guess my PC was about 6 feet from that jig and the USB mouse on the PC was hung after test and needed to be power cycled.   This is pretty common problem with USB. It's not a robust bus.   I suspect on the LeCroy that the noise was causing the LCD interface to get corrupt.   Beyond the LCD and the mouse shutting down, there were no other problems.

I see. Having blown or crippled inputs in the past, I tend to go a bit overboard in input protection/shielding. The LCD is the largest non-shielded part of the oscilloscope, therefore it is probably the most affected by EMI surges. Under certain circumstances I see this happening in my Rigol DS4014 as well.

I think the USB (and perhaps a keyboard) are your PC's "antennas" that capture all EMI spikes. Tie these with thinner shielded cables (the norm these days) and you probably get the most susceptible part of your PC.

[joeqsmith]

I see. Having blown or crippled inputs in the past, I tend to go a bit overboard in input protection/shielding. The LCD is the largest non-shielded part of the oscilloscope, therefore it is probably the most affected by EMI surges. Under certain circumstances I see this happening in my Rigol DS4014 as well.

I think the USB (and perhaps a keyboard) are your PC's "antennas" that capture all EMI spikes. Tie these with thinner shielded cables (the norm these days) and you probably get the most susceptible part of your PC.

There's nothing wrong with being overly safe.  You may have seen my spark gaps and diode clamps that I use from time to time when I play with high voltages.    I have been lucky that I have never damaged the front end of a scope.   Not like I haven't put them at risk!   

My old LeCroy front end actually has a battery in it that is used for part of the input protection when the scope is powered down.  The WR will open the connector and ground the ADC, which is more what I would expect .

They make a transparent film for EMI that can be placed over something like an LCD.  I wonder if the more modern industrial displays don't have some sort of layer on the glass.     

Line cord and Ethernet cables as well.  The unshielded Ethernet is fairly robust.  That USB with it's common mode problems, not so much.   Most of the USB devices I have will reset or hang when I play with the ignitions.

[joeqsmith]

I put together a video showing the power measurement software with some different loads.   Labview sets up the LeCroy and then downloads several cycles.   I used the Brymen to calibrate the current and voltage.  It would be fun to try a commercial product and see how they compare with some different waveforms.     

[joeqsmith]

After making the first power measurement video, I posted here about my attempting to improve the measurement. 

https://www.eevblog.com/forum/testgear/making-accurate-low-frequency-measurements-with-your-scope/30/

In this video I put the oversampling into practice.   

[joeqsmith]

I picked up one of those in-line AC power meters and compared it with the DSO.  It seems to work pretty good.  Keep in mind that the meter is plugged in downstream from the DSO's monitor.  So the DSO is reading both the load and the power meter.