EEVblog #585 - Lab Bench ESD Matting Upgrade + Tagarno HD Microscope

[Dave Turner]

A thought, is there any advice on how many square metres a single ground point will be sufficient for this type of mat? Or is a single point sufficient no matter the size of the mat? I would think that there must be some limit.

[linux-works]

I was asking that, too.  seems  that if its high R, you'd want frequent snaps on the mat so that you can keep it well grounded at every quadrant.  I have not seen this done before but would it be such a bad idea?

it looks like you can buy (and install) those 'star snaps' but if its not worth the effort, that's cool.  otoh, if there is some benefit to having them every 'n' inches, it would be nice to know.  I ordered a 72" long mat (that fits my existing table perfectly; 30x72) and that seems like a long distance to have only 1 ground point.

[Dave Turner]

Another point to consider is one's wrist strap connection(s).  Where should they be relative to the mat's earth point.

I note that Dave has under bench points for earthing and wrist straps. This makes sense as one would prefer to avoid connectors on the mat where tear-out/friction might occur whilst moving or dragging kit around.

With a small bench, like mine, this is all practically irrelevant but if one is fortunate enough to work on large benches where should the line be drawn?

I confess that I worked for many years both in the field and in the lab without using mats or wrist-straps and never fried anything due to static. That is because I always ensured that I was discharged and maintained a connection with a mutual earth with the DUT. Even to the extent of wrapping a toe round a radiator (before plastic plumbing).

Even with good earthing and my nice new mat I doubt that I shall change my old style safety habits which have become ingrained. Of course HV safety is different!
 

[zapta]

He is a certified fitness instructor as well........

And expert in online dating...

http://www.artofinternetdating.com/

[linux-works]

given how star grounding works, I would assume (correct me if wrong) that the mat would be grounded to a point of ground that is a central location.  that same location would also feed the wire for the 'console' dual banana jack outlet.  that way, they are not directly connected 'away' from ground but they are more local to the ground and to flow from wrist strap to the mat would mean 2x the travel.

daisy chaining grounds is always a no-no with me, so I would centrally locate the wires from the banana jack console and the wire from the mat.

[Kempy]

How about this idea?:

Cut the old esd mat into squares and sell it off on eBay as EEVblog souvenirs 

[GreyWoolfe]

ESD mats are grounded to mains earth, usually through a 1M resistor. A little stud like this http://pcvalet.co.uk/UsedImages/ThickBox_pcvalet-anti-static-mat-stud-connectors.jpg is usually crimped into the mat, and is connected to mains earth though a specialised wall plug.

My common ground point cord has a banana plug on the end.  I went to home depot and bought a standard 3 prong plug, removed the hot and neutral pins and I soldered a low profile banana jack to the ground pin.  the rubber boot around the plug holds the jack in place and it plugs normally into a grounded wall outlet.  Works a beauty

[Rasz]

Stumbled upon this picture when searched google for 'Tagarno'.  Apparently it brings peace and love to the workplace.  Two thumbs up!

They are so happy because apparently Tagarno corrects angled shots on the fly! Buildin photoshop and image stabilization


Cant wait for Tagarno review, hopefully along with that crappy chinese USB scope and HK M$ lifecam one for comparison.

[BravoV]

Cant wait for Tagarno review, hopefully along with that crappy chinese USB scope and HK M$ lifecam one for comparison.

"What if" the cheap Chinese MS WebCam + Lens mod job result is comparable to the $$$$ Tagarno ? 

[linux-works]

then, those two 'happy-guys' won't be so happy anymore?

(grin)

[BravoV]

then, those two 'happy-guys' won't be so happy anymore?

(grin)

Geez... why so negative, you're wrong, all will be happy since both will have one each of the Chinese knock-off, no more fighting whenever they need it at the same time. Also there will be a 3rd guy, happy too, since he is their boss and apparently he got his money back by returning the Tagarno and saved plenty of bucks. 

[Rasz]

Cant wait for Tagarno review, hopefully along with that crappy chinese USB scope and HK M$ lifecam one for comparison.

"What if" the cheap Chinese MS WebCam + Lens mod job result is comparable to the $$$$ Tagarno ? 

It could in theory be comparable in that one (fixed focus) position with enough light hitting the object, and I sure hope it will
But it still wont be a substitute. Hdmi out and zoom/focus control (probably also autofocus) means comfy standalone work without mucking around with a computer and trying to get your thingie in position. Still those are sacrifices I can make for ~$3K

[mikepa]

Dave,

How many power circuits do you have for your bench?  In the US we have 20A 120V outlets giving 2400W - what do you have in Oz?

[moemoe]

How many power circuits do you have for your bench?  In the US we have 20A 120V outlets giving 2400W - what do you have in Oz?

As their plug is rated for 10A, https://en.wikipedia.org/wiki/AS/NZS_3112 they probably have 2,3kW available.

[AmmoJammo]

How many power circuits do you have for your bench?  In the US we have 20A 120V outlets giving 2400W - what do you have in Oz?

As their plug is rated for 10A, https://en.wikipedia.org/wiki/AS/NZS_3112 they probably have 2,3kW available.

Australian voltage is 240
And It's quite possible that Dave has two power outlet circuits in the room, so two 10amp circuits.

[moemoe]

Australian voltage is 240
And It's quite possible that Dave has two power outlet circuits in the room, so two 10amp circuits.

Then, go and correct the above Wikipedia article: "A standard power outlet in Australia provides a nominal voltage of 230 volts at a maximum of 10 amps and always includes an earth connection."

[EEVblog]

Australian voltage is 240

It's 230V officially. Still 240V in many areas like my lab and home.

[EEVblog]

How many power circuits do you have for your bench?  In the US we have 20A 120V outlets giving 2400W - what do you have in Oz?

I have a total of 3 x 4 outlet power points along that wall, with 4 x 6way power boards plugged into each one. The total available current for that half of the lab (and hence all outlets combined across the whole banch) is fused at 20A total. The other side of my lab has a separate 20A circuit.

[David_AVD]

We have 4 benches in a line at work fed from a 32A breaker in the switchboard.  Each bench has a 20A RCD/MCB that feeds 5 double GPOs; 2 on front edge (for heat gun and items under test), 1 underneath (for soldering iron, etc), 1 at rear (for test gear) and 1 above (for test gear via power boards).

The computers (one per bench) are fed from a single large UPS that is independent of the bench power.  Other side of the room has a bench with 20A supply (with 3 double GPOs) and 32A 3-phase for testing lighting equipment.

Each bench has a low average power requirement, so the 32A overall limit (~ 7.5KW) is not an issue.  If we need something more for a specific job, we can plug in a 3-phase distribution board (mix of 10A and 15A sockets) to pull about another 23KW from the 3-phase socket.

Having independent breakers (and RCDs) is very useful in a test / development environment.  Not as easy to do if your benches are free standing and you like to rearrange things from time to time of course!

[darko31]

Regarding the lab PC, it would be somewhat cheaper using a small form factor desktop PC than a high end laptop. You already have tons of monitors, an mini ITX based case and motherboard could support any CPU.

[mikepa]

How many power circuits do you have for your bench?  In the US we have 20A 120V outlets giving 2400W - what do you have in Oz?

I have a total of 3 x 4 outlet power points along that wall, with 4 x 6way power boards plugged into each one. The total available current for that half of the lab (and hence all outlets combined across the whole banch) is fused at 20A total. The other side of my lab has a separate 20A circuit.

Interesting, so each circuit from the distribution panel can handle 20A @ 230V.  Can you get that out of one socket for a tool that needs a lot of power (such as a large (3HP) table saw)?  In the US we also have 220V 20A outlets for power tools and stoves (cookers).

[VK3DRB]

Australian voltage is 240

It's 230V officially. Still 240V in many areas like my lab and home.

Correct. AS60038 - 2000 states a nominal of 230V.

http://www.ausgrid.com.au/Common/Our-network/Standards-and-Guidelines/~/media/Files/Network/Documents/ES/ENOS_Oct2011.pdf

My place is about 255 to 258V... it is quite high. It went high when some electricity distribution company installed a new step down transformer at the end of the street. The high voltage has not caused any problems, although I do wonder if any of my equipment might have a shortened lifespan. Years ago I would have worried, but not so much now we can get cheap replacements made by exploited Chinese workers.

[EEVblog]

Regarding the lab PC, it would be somewhat cheaper using a small form factor desktop PC than a high end laptop.support any CPU.

The Targarno doesn't work on my laptop anyway I found out. Nor does it work on my high end video editing desktop. Something is horrible wrong with the setup...

[EEVblog]

Interesting, so each circuit from the distribution panel can handle 20A @ 230V.  Can you get that out of one socket for a tool that needs a lot of power (such as a large (3HP) table saw)?

No. Standard power points here are rated at 10A (2400W). With usually 15A capable wiring and a 15A breaker per circuit (mine has 20A breakers). You can get 15A outlets that have a physically larger earth pin, so the cable can't be accidentally plugged into a 10A outlet. There are additional legal wiring requirements for those 15A outlets.
You can have as many points as you want hanging off your one 15A/20A capable circuit, but no more than 10A per outlet, and a total power of that 15A obviously.

[GiskardReventlov]

The Targarno doesn't work on my laptop anyway I found out. Nor does it work on my high end video editing desktop. Something is horrible wrong with the setup...

Defective unit?