Setup an o'scope with a probe as the antenna.
Details unimportant, as long as o'scope is fast enough.
Power supply scopes of 5-10 Mhz are a little slow.
A few hundred megs should suffice to show any effects.
I like auto trigger. Captures what happens and holds it.
Adjusts will be necessary to tune in to the effects.
For air discharge, press the trigger to prepare for the approach.
Move closer to the o'scope probe.
Try again.
After discharge to target, and before releasing trigger,
move close to probe and release trigger.
Ot locate probe near target.
Simple spacing of timing of trigger on, approach and discharge, then trigger
off,
Can be illuminating, especially if product glitches at times other than
discharge.
My personal fix for use during debug, is to arm trigger at a very small
distance from target.
while not per standard, it does give consistent and repeatable results that
when fixed, results in the product passing the usual requirements per the
standard.
ps. I also use this technique to verify the waveform per the standard.
I can get 10/10 first time. So RCL circuit is working.
And I know the cal lab will get correct results, eventually.
pps. just a personal opinion, approaching really fast without causing damage is
so silly as to be beyond ridiculous.
How fast is lightning, an ESD spark ?
Approach really slow and note what static discharges that happen with a charged
tip.
How many humans have a regulated approach speed for the air discharge?
Vertical and horizontal planes show a good example of the effects.
Thus the instruction to approach really fast.
But ... Humans verses lightning bolts ??
While that fancy vacuum switch in the ESD gun that you paid a lot for can do
that in an near instant !
and consistently too !
Some ESD guns are really bad at pre and post discharges, causing product
failures at a distance and so do not seem to be related to the product testing
going elsewhere in the lab.
Which hints at using a chamber for ESD testing in order to avoid affecting
other tests.
An analogy is playing with grenades...
On Wednesday, November 6, 2019, 05:12:03 PM EST, doug emcesd. com
<[email protected]> wrote:
No decent ESD gun should emit EMI pulses in the air mode, the contact relay
should stay quiet while the tip slowly (milliseconds) charges up. Most guns do
not do this and fire the contact relay at which point you do not actually know
the voltage of the air discharge. The only gun that does air discharge
correctly, in my technical opinion after working in ESD for the last 35 years,
is the KeyTek Mini-Zap. It works in a completely different way and is the only
gun I am aware of that you know for sure exactly what voltage the air discharge
happened at. You can also use it to charge objects, like me, to known voltages
(just did that for some ESD research, and also use it for a high voltage
breakdown tester.
Doug
From: Bill Owsley <[email protected]>
Sent: Tuesday, October 15, 2019 22:09
To: [email protected]
Subject: Re: [PSES] Any Different Results in ESD Testing when Changing Brands
of ESD Simulator (IEC 61000-4-2)
One example that comes to mind, out of a long history of wonderment in ESD
testing, is for an air discharge, pulling the trigger causes the product to
glitch, before approaching the product target point.
Found a way around the anomaly, to find not problem with the actual air
discharge.
But then a moment later, releasing the trigger caused another glitch.
Sent ESD gun for repairs and got a 'no defect found' result.
Sent to an independent calibration lab of notable credentials, for a good to go
results.
Repeat test in our lab with the same glitchy results.
ps. on the side, I monitor the radiated emissions by using an o'scope with a
simple probe hanging open loop somewhere nearby.
The scope captured waveform indicated a wild radiated event when pressing the
trigger for an air discharge.
With resulting products glitches.
Another waveform for the actual spark, and no product glitches.
Followed by another wild radiated event upon releasing the trigger, that also
caused glitches.
Verification of the ESD waveform by using a "target" was also monitored with an
independent scope.
A thought occurred that an ESD event happens so much faster than any human
movement to move the gun towards the target fast without causing damage, that
it is silly to do so.
So I tried placing the tip a small distance from the target.
The monitoring scope indicates that the arming and air discharge seems to
happen at the same time.
The trigger release still causes the radiated event, which often triggers
another air discharge.
With the close spacing between ESD gun probe and verification target, the
immediate discharge keeps the dual discharges away.
And the waveform is nearly text book perfect, every time.
Verified !
On Tuesday, October 15, 2019, 03:50:55 PM EDT, John Woodgate <[email protected]>
wrote:
Well, some of the set-ups I've seen appear to accept violent mismatches, so
concern about the cables may not be misplaced. But I still think that an
in-depth study of the discharge path, from source back to source, is needed.
What is a 'reasonable waveform definition'? Do you mean a precise definition of
a realistic waveform? I think that IEC 61000-4-2 has a precise definition, but
I have no idea whether the waveform is realistic, even less whether is it a
reasonable 'average' of a range of possible waveforms. But we must note that it
is a specification to be met under verification test conditions: itdoes not
claim to be the waveform that actually occurs during any specific immunity
test. It could not possibly claim that.
Best wishes John Woodgate OOO-Own Opinions Only J M Woodgate and Associates
www.woodjohn.uk Rayleigh, Essex UK
On 2019-10-15 20:06, doug emcesd.com wrote:
Well said, Derek!
I am always amazed that EMC people worry about the measurement uncertainty of
the coax cable that connects the target to the scope yet ignore factors, like
lack of reasonable waveform definition, that have orders of magnitude more
effect on the EUT.
Doug
Sent from my iPhone
IPhone: 408-858-4528
Office: 702-570-6108
Email:[email protected]
Website:http://dsmith.org
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<[email protected]>
All emc-pstc postings are archived and searchable on the web
at:http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities site
athttp://product-compliance.oc.ieee.org/ can be used for graphics (in well-used
formats), large files, etc.
Website:http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <[email protected]>
Mike Cantwell <[email protected]>
For policy questions, send mail to:
Jim Bacher <[email protected]>
David Heald <[email protected]>
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<[email protected]>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used
formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <[email protected]>
Mike Cantwell <[email protected]>
For policy questions, send mail to:
Jim Bacher <[email protected]>
David Heald <[email protected]>
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<[email protected]>
All emc-pstc postings are archived and searchable on the web at:
http://www.ieee-pses.org/emc-pstc.html
Attachments are not permitted but the IEEE PSES Online Communities site at
http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used
formats), large files, etc.
Website: http://www.ieee-pses.org/
Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas <[email protected]>
Mike Cantwell <[email protected]>
For policy questions, send mail to:
Jim Bacher: <[email protected]>
David Heald: <[email protected]>
