So... to be clear, the opening in the center of the Faraday box is where the field enters. One leaf vibrates, causing the field to be modulated. That AC signal is then more easily amplified than a DC signal would be, which is the reason for every chopper amplifier. It appears this is well suited to close measurement in the range of an inch or less, where the rotating fieldmill is better suited to measuring from much greater distances, with corrections for distance. I love that method of setting accurate distance. Two LEDs angled to hit the same spot at 1 inch, but then they are both alternately blinking. So when the spots perfectly align, it is a constant light. Even a little error in the distance appears as blinking where they don't overlap.
Thanks for the great video. Wonderful content as always. As you mentioned… I thought these were normally extremely expensive even on the used market. But now that I’m looking online…I seem to find these pretty cheap used on eBay. I picked up a Simco “hand-e-stat” new in the box, I got it as part of a test equipment lot I purchased a few days ago. It basically cost me nothing. The build quality is great. But I see they have sold on eBay for under $100. It works great with a very similar operating principle and layout. So I’m not sure where I got the idea that these were always extremely expensive I think it’s most useful for working with lasers and laser diode‘s. Considering they are the most sensitive device I’ve ever worked with or seen anyone work with. They are by far the most commonly fried device I’ve ever seen. I’ve had ZERO other issue with static. I’ve bought oscilloscopes and old test gear that were disassembled and rummaging around on a carpeted floor for decades. Only to be put back together and work flawlessly. That’s when I stopped worrying about static. Not claiming static isn’t a real issue… But I’v never seen a problem outside of laser diodes. But I fried several laser diode‘s with static… And most any laser hobbyists have also. It’s unbelievable how sensitive they can be. Talk about upsetting… Try frying a beautiful piece of technology & extremely rare laser diode!!! They can range from $30-$150… And laser modules containing multiple diode‘s or high power pumped modules can cost hundreds or thousands. I was Lucky to find a coherent 60W laser modules for under $100. But I really want a Jenoptik fiber coupled laser module. Hopefully 40W or greater. But they are hundreds or thousands of dollars. I would be sick at my stomach to fry one of them. So I always practice ESD safety when working with lasers. Thanks again for your videos.
Scopes and old test gear generally aren't ESD sensitive until you start taking apart newer stuff based on CMOS circuits. The first generation of CMOS logic chips were terribly sensitive to ESD damage, the newer stuff has ESD protective diodes on all input pins. But those diodes are not meant to take a lot of abuse. Also, keep in mind that the first signs of ESD damage are generally very subtle and hard to detect, but will cause eventual degradation and failure in the figure. Slightly higher current draw, slightly degraded frequency response, slightly lower input impedance. High power LEDs are degraded by ESD, too.
Compared to GOhm, contact resistance is negligible. However, wall currents and static charge will cause fluctuations that can be minimized by connecting the guard shield layer in the cable to a guard conductor around the DUT. GOhm times nF gives 1 s time constants for reasonably sized internal Faraday cages.
I wounder if they've improved on this type of meter since 1996? Frankly, this is the first time I've seen an electronic measuring device for ESD. I've only seen the primitive Henley electrometers or electroscopes that would react near a charged object. I'm going to look into the availability of this device to see if there are cheaper options.
You can find these kind of ESD measurement devices on ebay (like this one www.ebay.com/itm/232351641704?_trksid=p2060353.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT) and some times they can be bought with reasonable price.
While that's a very neat piece of kit, I actually found the angled LED trick the most interesting! As it happens, the same technique was used during the Dambusters raid during WW2 to accurately set the height of the bombers during their run: www.thedambusters.org.uk/height.html. I can't think I've seen the method used on anything else.
Thanks for sharing. Interesting tool. What is the big black outline of an IC with a cylinder in the middle, right in the middle of the board? Is that just a way to mount a particular IC?
So... to be clear, the opening in the center of the Faraday box is where the field enters. One leaf vibrates, causing the field to be modulated. That AC signal is then more easily amplified than a DC signal would be, which is the reason for every chopper amplifier.
It appears this is well suited to close measurement in the range of an inch or less, where the rotating fieldmill is better suited to measuring from much greater distances, with corrections for distance.
I love that method of setting accurate distance. Two LEDs angled to hit the same spot at 1 inch, but then they are both alternately blinking. So when the spots perfectly align, it is a constant light. Even a little error in the distance appears as blinking where they don't overlap.
Chopper stabilized eliminates input offset voltage rather than input bias current.
Thanks for the great video. Wonderful content as always.
As you mentioned… I thought these were normally extremely expensive even on the used market. But now that I’m looking online…I seem to find these pretty cheap used on eBay. I picked up a Simco “hand-e-stat” new in the box, I got it as part of a test equipment lot I purchased a few days ago.
It basically cost me nothing. The build quality is great. But I see they have sold on eBay for under $100. It works great with a very similar operating principle and layout. So I’m not sure where I got the idea that these were always extremely expensive
I think it’s most useful for working with lasers and laser diode‘s. Considering they are the most sensitive device I’ve ever worked with or seen anyone work with. They are by far the most commonly fried device I’ve ever seen.
I’ve had ZERO other issue with static. I’ve bought oscilloscopes and old test gear that were disassembled and rummaging around on a carpeted floor for decades. Only to be put back together and work flawlessly. That’s when I stopped worrying about static.
Not claiming static isn’t a real issue… But I’v never seen a problem outside of laser diodes. But I fried several laser diode‘s with static… And most any laser hobbyists have also. It’s unbelievable how sensitive they can be. Talk about upsetting… Try frying a beautiful piece of technology & extremely rare laser diode!!! They can range from $30-$150… And laser modules containing multiple diode‘s or high power pumped modules can cost hundreds or thousands.
I was Lucky to find a coherent 60W laser modules for under $100. But I really want a Jenoptik fiber coupled laser module. Hopefully 40W or greater. But they are hundreds or thousands of dollars. I would be sick at my stomach to fry one of them. So I always practice ESD safety when working with lasers. Thanks again for your videos.
Scopes and old test gear generally aren't ESD sensitive until you start taking apart newer stuff based on CMOS circuits. The first generation of CMOS logic chips were terribly sensitive to ESD damage, the newer stuff has ESD protective diodes on all input pins. But those diodes are not meant to take a lot of abuse.
Also, keep in mind that the first signs of ESD damage are generally very subtle and hard to detect, but will cause eventual degradation and failure in the figure. Slightly higher current draw, slightly degraded frequency response, slightly lower input impedance.
High power LEDs are degraded by ESD, too.
Compared to GOhm, contact resistance is negligible. However, wall currents and static charge will cause fluctuations that can be minimized by connecting the guard shield layer in the cable to a guard conductor around the DUT. GOhm times nF gives 1 s time constants for reasonably sized internal Faraday cages.
Great Video very informative
I wounder if they've improved on this type of meter since 1996? Frankly, this is the first time I've seen an electronic measuring device for ESD. I've only seen the primitive Henley electrometers or electroscopes that would react near a charged object. I'm going to look into the availability of this device to see if there are cheaper options.
You can find these kind of ESD measurement devices on ebay (like this one www.ebay.com/itm/232351641704?_trksid=p2060353.m1431.l2649&ssPageName=STRK%3AMEBIDX%3AIT) and some times they can be bought with reasonable price.
While that's a very neat piece of kit, I actually found the angled LED trick the most interesting! As it happens, the same technique was used during the Dambusters raid during WW2 to accurately set the height of the bombers during their run: www.thedambusters.org.uk/height.html. I can't think I've seen the method used on anything else.
Thanks for the info!
Thanks for sharing. Interesting tool. What is the big black outline of an IC with a cylinder in the middle, right in the middle of the board? Is that just a way to mount a particular IC?
Yeah, that was just part of the socket, there was nothing underneath.