Science and Technology news... :: View topic - Surge protectors to use with home electronics when grounding

ånønÿmøu§ · Guest

On Sun, 18 May 2008 19:20:39 GMT, Hammy <spamme@hotmail.com> wrote:

[quote]
What is the benefit with comparators that have a Hysteresis pin?

I>m using one the LTC1440 and I don>t see any benefit you still
require two resistors for Hysteresis. Is the Hysteresis pin tied
internally to the output (positive feedback)?

If I wanted to use this comparator in an inverting mode can I still
use the suggested method in the application note for Hysteresis
(pg.11)? Or should I use the standard method a resistive divider off
the output back to the reference?

LTC1440 Datasheet (Hysteresis is on pg.11)

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1002,C1463,P1172,D2764

Hysteresis for inverting comparator

http://i32.tinypic.com/29bozeu.png

Thanks
This pin can only apply up to 100mV +/- 15% of Hysteresis.[/quote]
Its faster in the since that its only swinging 100mV around.
Most of the time I will measure the Hysteresis to see just how much is
really needed. This is completely dependent upon the noise at the
input to the comparator.
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John Fields · Guest

On Sat, 28 Jun 2008 16:39:50 -0700 (PDT), w_tom <w_tom1@usa.net>
wrote:

[quote]On Jun 28, 10:23 am, John Fields <jfie...@austininstruments.com
wrote:
So where is this proof? Current is coming down any or all AC wires
is still seeking earth ground.

---
No, it>s seeking Neutral.
...
Now let>s say that a lightning strike somewhere on the HV side of the
supply has caused a 1000V spike to occur across the half of the
secondary to which our appliance is connected.

All of a sudden, then, the voltage across the appliance will rise to
1000V, the current through it will rise to:
...
Clearly, at this point the appliance is in serious trouble

The solution?

A plug-in protector interposed between the load and the mains, like
this:
...
Normally, the MOV will appear to be an open circuit and will draw no
current, but what will happen when the lightning strikes is that when
the voltage across the MOV rises to 150 volts, it will break down and
allow current to flow through itself until such time as the mains
voltage falls below 150V, when it will once appear to be an open
circuit.

The reason for its use in the circuit is to prevent the voltage across
the appliance from rising to more than 150 volts, therefore providing
it with some modicum of protection against transients as can be seen
by considering that with 150V across the appliance it will be drawing
1.25 amperes and dissipating 187.5 watts, a far cry from 8.3 amperes
and 8300 watts.

Which is all nice and good except that ohms resistance has near zero
relevance. As every responsible citation notes, *impedance* is the
critical factor. Whereas that neutral or ground wire via 50 feet of
romex may be less than 0.2 ohms, that same wire is maybe 120 ohms
impedance. Why? Wire is too long, too many splices, too many sharp
bends, etc.

A 100 amp surges is trivial. A trivial 100 amp surge 'clamped' by
the protector puts that protector at something less than 12,000
volts. That 12,000 volts puts all nearby TVs at risk as demonstrated
on Page 42 Figure 8. John – even 150 volts between H-N still means
all wires are at something less than 12,000 volts to earth.
[/quote]
---
But, what>s important is that, at the appliance, the TVS clamps the
voltage between line and neutral to 150V regardless of the line
impedance.

Likewise, if another appliance at another outlet was protected by a
TVS then it would be irrelevant what common mode voltage existed on
either set, the voltage from line to neutral would still be limited to
150V.
---

[quote]Both 'top of the front page' articles in Electrical Engineering
Times discuss this in "Protecting Electrical Devices from Lightning
Transients" published 1 Oct and 8 Oct 2007:
The length of the cable increases the impedance dramatically.
[/quote]
---
Not really.

Since the conductors in the cable run parallel to each other the cable
is actually a transmission line and will exhibit some characteristic
impedance. Here:

http://en.wikipedia.org/wiki/Characteristic_impedance
---

[quote]Why does that responsible sources discuss impedance? Because surge
protection requires low *impedance* earthing which a plug-in protector
does not provide.
[/quote]
---
Sigh... You _still_ don>t get it.

What matters, as far as protection of the appliance is concerned,
isn>t the common mode voltage on the cable conductors, it>s the
voltage between line and neutral.

Which is why TVSs are effective, since they clamp that voltage to some
safe maximum which the appliance can stand momentarily.
---

[quote]In many cases a protector should be bonded to a ground plane, ...
Often a ground grid is used to provide low impedance across the
ground plane. To intercept lightning, overhead grounded shield
wires can also be bonded to this ground plane. ...
Lightning is essentially a current impulse which is trying to return to earth.
[/quote]
---
No, lightning is a very high _voltage_ impulse which causes immense
currents to flow when it strikes. Without the pressure of the voltage
causing an ionization path from the source cloud to earth, no current
will flow.
---

[quote]... grounding here refers to the connection to the soil, which (hopefully)
will be the preferred path of lightning current.

Ground is what lightning seeks - earth ground. That protector must
be bonded *low-impedance* to earth ground. Not low resistance as John
Fields discuss. Low impedance which is why an earth ground for surge
protection is typically 'less than 10 feet'.
[/quote]
---
Look at the subject line to learn why all your prattle about earth
ground is immaterial.
---

[quote]Why do responsible sources discuss sharp bends, splices, and wire
inside metallic conduit? None of these increase resistance - what
John discusses. All drastically increase impedance. *Low impedance*
(not resistance) defines effective protection.
[/quote]
---
Actually, from the POV of a plug-in TVS, the higher the impedance of
the line the better, since that will limit the current into the TVS
and thereby prolong its life, assuming an MOV is the TVS.

From a previous post, we have:

..HV>--+ +-----<<-----+------<<----+
.. | | | |
.. | | [PROTECTOR] [LOAD]
.. P||S | |
.. R||E-----<<-----+------<<----+
.. I||C
.. | |
.. | |
..HV>--+ +------L2

Now, lets modify it a little to show the wiring resistances of L1 and
Neutral:

..HV>--+ +--L1-------[Rl]---------<<-+----<<----+
.. | | | |
.. | | [PROTECTOR] [LOAD]
.. P||S | |
.. R||E--N--------[Rn]---------<<-+----<<----+
.. I||C
.. | |
.. | |
..HV>--+ +--L2

and redraw it for convenience, leaving out the transformer primary:

.. L1
.. |
.. +---E1
.. |
.. [Rl]
.. |
.. +---E2
.. |
.. [TVS]
.. |
.. +---E3
.. |
.. [Rn]
.. |
.. +---E4
.. |
.. N

Using a 50' run of 14AWG for the conductor results in Rl and Rn both
having a resistance of about 0.13 ohm, which means that with a 1000V
surge on the secondary of the transformer (between L1 and N) the
current through the TVS will rise to about:

E1 - (E2-E3) 1000V - 150V
I = ---------------- = ----------------------- = 2073 amperes
Rl + Rtvs + Rn 0.13R + 0.15R + 0.13R

Using your figure of 120 ohms for the impedance of each of the
conductors and replacing Rl and Rn with Zl and Zn, we have:

E1 - (E2-E3) 1000V - 150V
I = ---------------- = ----------------------- = 3.539 amperes
Zl + Rtvs + Zn 120R + 0.15R + 120R

So it>s easy to see that, in this instance, the impedance has
dramatically reduced the current the TVS must pass while clamping the
voltage across the appliance to 150V and, in contrast to your
statement that the shorter the cable the better, if impedance
increases with length, the longer the better.

Snipped a lot of irrelevant crap...

JF

bud-- · Guest

w_tom wrote:
[quote]On Jun 27, 10:42 am, bud-- <remove.budn...@isp.com> wrote:

Lacking valid technical arguments w_ invents issues.

Plug-in suppressors have MOVs from H-G, N-G, H-N. That is all possible
combinations and all possible surge modes.

Bud lies.
..[/quote]
Bud repeat the "lies" of the IEEE and NIST.
..
[quote]Even a well respected researcher notes the problem with plug-in
(point of connection) protectors in his IEEE paper. Martzloff says:
..[/quote]
w_ forgets to mention that Martzloff said in the same 1994 document:
"Mitigation of the threat can take many forms. One solution. illustrated
in this paper, is the insertion of a properly designed surge reference
equalizer [multiport plug-in surge suppressor]."

In 1994 multiport suppressors were rather new.

In 2001 Martzloff wrote the NIST guide which also says plug-in
suppressors are effective.

Because plug-in suppressors violate w_>s religious belief in earthing
he has to twist what Martzloff says about them.
..
[quote]A protector is only as effective as its earth ground.
..[/quote]
The required statement of religious belief in earthing.

If w_ could read, the IEEE guide explains plug–in suppressors work
primarily by clamping the voltage on all wires (power and signal) to the
common ground at the suppressor. The voltage between wires going to the
protected equipment is safe for the equipment. Plug-in suppressors do
not work primarily by earthing. The guide says earthing occurs elsewhere.

Still never seen - a link to another lunatic that agrees with w_ that
plug-in suppressors are NOT effective. Why doesn’t anyone agree with you
w_???

Still never answered - embarrassing questions:
- Why do the only 2 examples of protection in the IEEE guide use plug-in
suppressors?
- Why does the NIST guide says plug-in suppressors are "the easiest
solution"?
- How would a service panel suppressor provide any protection in the
IEEE example, pdf page 42?
- Why does the IEEE guide say in the example "the only effective way of
protecting the equipment is to use a multiport protector"?
- Why does SquareD say "electronic equipment may need additional
protection by installing plug-in [suppressors] at the point of use."
- Where is the link to a 75,000A and 1475Joule rated MOV for $0.10.
– How can SquareD be a "responsible" company when there is no "spec that
lists each type of surge and protection from that surge".

- Was the UL standard revised as w_>s own hanford link said?
- Did that revision require thermal protection next to the MOVs as w_>s
own hanford link said?
- What was the date of that revision - which w_>s own hanford link said
was UL1449 *2ed*?
- Where specifically in any of w_>s links did anyone say a damaged
suppressor had a UL label?
Where are your answers w_???

--
bud--

Tom Biasi · Guest

"steve" <kvsteve@gmail.com> wrote in message
news:f2dfde6b-bb1b-461f-98d7-e08cf85fea76@z32g2000prh.googlegroups.com...
On Jun 26, 7:56 pm, "Tom Biasi" <tombiasi...@optonline.net> wrote:
[quote]"steve" <kvst...@gmail.com> wrote in message
[/quote]
-----------------------------------------------------------------
This project was difficult to design, so preferably it should be kept
same.

I will provide the schematic shortly.

Steve.

If its too much trouble for you to fix your design then the only other
choice is to supply it with clean DC.
Tom

JeffM · Guest

Mark Borgerson wrote:
[quote]Don>t mix up ExpressPCB and PCB Express.
The latter is a division of Sunstone[...]
Sunstone also has their own free PCB suite, PCB123.
[/quote]
Pad2Pad, ExpressPCB, & PCB123 are all essentially the same thing.
They are all lock-in-ware.
Their output is NOT portable between fab houses.
None of them produce Gerbers.

steamer · Guest

Tom2000 <abuse@giganews.net> wrote:
[quote]If you>ve found a cheap, light-duty controller that meets your
timing and sequencing needs, consider having it drive relays instead
of EL strings. Then drive your EL strings from the relays.
[/quote]
--Hey I like that! Thanks for the idea!

--
"Steamboat Ed" Haas : "Hold on! we>re passing
Hacking the Trailing Edge! : through the moronosphere!"
www.nmpproducts.com
---Decks a-wash in a sea of words---

w_tom · Guest

You still don>t get it. Voltage between line and neutral -
especially if using a plug-in protector - is near zero. Typically
well below what internal protection in any appliance does. Common
mode voltage (whether plug-in protector exists or not) is the 8000
volts destructively across an adjacent appliance - Page 42 Figure 8.
How many sources must note this because you get it? Lightning seeks
earth ground. It finds a path to earth destructively via the
appliance. What is that thousands of volts? While you discuss trivial
hundred voltage surges that harm nothing, those thousands of volts is
common mode - it seeks earth ground.

Characteristic impedance is not relevant. Why do you confuse
characteristic impedance with wire impedance that is completely
different? Current is in the same direction on one or all wires -
seeking earth ground. Therefore characteristic impedance obviously is
not relevant. Why do responsible sources that discuss surge
protection not discuss characteristic impedance? It obviously is not
relevant.

An MOV shunting (connecting, conducting) 150 volts between two wires
means either the MOV conducts no current (because a voltage is same on
both wires) or the MOV simply provides a surge more paths to find
earth ground destructively via the adjacent appliance. An MOV at the
appliance is for surges that typically don>t overwhelm protection
already inside all appliances.

Why do telcos not use your MOV solution? It does not provide
protection from surges that typically cause damage AND that surge it
would protect from what is also made irrelevant by the 'whole house'
protector. Yes, the 'whole house' protector is protection from all
types of surges. A more expensive plug-in protector protects from one
type of surge that typically causes no damage.

Telcos are not into enriching plug-in protector manufacturers.
Telcos need protection that works. That means a properly earthed
'whole house' protector on each incoming wire and no plug-in
protectors. At what point do you claim to be smarter than telcos all
over the world?

Sigh - you still don>t get it. There is no responsible source
citing what you have been posting. The Electrical Engineering Times
articles are entitled "Protecting Electrical Devices from Lightning
Transients". Why do they discuss earthing and completely ignore plug-
in protectors? Look at the title. EE Times does not promote popular
myths. Why do those articles discuss wire impedance (which is not
characteristic impedance)? Because effective protectors require low
impedance earthing. How many sources need be cited before John Fields
finally grasps the critical importance of low impedance earthing?
Even three IEEE Standards note what provides protection from typically
destructive surges - earth ground.

John Fields posts:
[quote]protection of the appliance ... isn>t the common mode
voltage on the cable conductors, it>s the voltage
between line and neutral.
[/quote]
No John. Voltage between line and neutral is near zero as a
destructive surge seeks earth ground (ie 8000 volts destructively) on
one or all of those wires. To promote grossly undersized and
obscenely overpriced plug-in protectors, then what is hyped to the
naive? Some irrelevant hot to neutral voltage - made irrelevant by
protection already inside appliances and also by a 'whole house'
protector.

Protection has always been about voltage between each wire and
earth. That protection also make voltage between hot and neutral
trivial. Effective surge protection means protection inside every
appliance is not overwhelmed. Protection not found in and not even
claimed by numeric specs for $25 or $150 plug-in protectors.

John - this is not rocket science. This was implemented even 100
years ago. After 100 years they are dumb and you know better? You
still don>t get it. Why do telcos not do what you have posted?
Effective protection is required. A protector is only as effective as
its earth ground. Same principle even applies to lightning rods.
Why do you have a problem with such well proven principles?

John Fields posted:
[quote]Look at the subject line to learn why all your prattle about earth
ground is immaterial.
And view an earliest reply. Solution is not three wire[/quote]
receptacles. Solution is earthing the breaker box to meet and exceed
post 1990 electrical code and one 'whole house' protector. Less
expensive than plug-in protectors. No three wire receptacles
required. Protection that is tens or 100 times less money per
protected appliance. Why do you promote plug-in protectors when even
the OP describes what plug-in protectors cannot be used on - two wire
receptacles? Why do you keep posting what is completely irrelevant to
the OP>s question?

Orange County FL was suffering damage to emergency response
facilities. How was surge damage eliminated? Plug-in protectors? Of
course not. Emergency facilities needed protection - not a myth.
Orange county fixed the reason for surge damage - earthing:
http://www.psihq.com/AllCopper.htm

A surge protector is only as effective as its earthing. How many
sources say this? Instead John Fields even confuses wire impedance
with characteristic impedance. A protector is only as effective as
its earth ground - where surge energy must be harmlessly dissipated.
Why do you repeat the myth promoted by retail salesmen? Where
effective protection is installed, protectors make that short (ie
'less than 10 foot') connection to a single point earth ground. Where
scams are promoted, well, how is that protector (that you promote)
acceptable on the OP>s two wire receptacles? It>s not.

On Jun 29, 9:36 am, John Fields <jfie...@austininstruments.com> wrote:
[quote]But, what>s important is that, at the appliance, the TVS clamps the
voltage between line and neutral to 150V regardless of the line
impedance.

Likewise, if another appliance at another outlet was protected by a
TVS then it would be irrelevant what common mode voltage existed on
either set, the voltage from line to neutral would still be limited to
150V.
...
Not really.

Since the conductors in the cable run parallel to each other the cable
is actually a transmission line and will exhibit some characteristic
impedance. Here:
http://en.wikipedia.org/wiki/Characteristic_impedance
...

Sigh... You _still_ don>t get it.

What matters, as far as protection of the appliance is concerned,
isn>t the common mode voltage on the cable conductors, it>s the
voltage between line and neutral.

Which is why TVSs are effective, since they clamp that voltage to some
safe maximum which the appliance can stand momentarily.
...[/quote]

Mark Borgerson · Guest

In article <tYCdnXlXl47nkMPVnZ2dnUVZ_sudnZ2d@posted.localnet>,
robertbaer@localnet.com says...
[quote]mpm wrote:

On Jun 21, 10:53ï¿=3Fam, Hauke D <hau...@zero-g.net> wrote:

Hi,

I>ve had good experiences with Advanced Circuits (http://www.
4pcb.com/). Make sure to use their free FDM service (http://www.freedfm..com/), even if you don>t end up going with them for
manufacturing.

ExpressPCB is only good for quick-and-dirty stuff. Their advantage is
that they>re cheap and their design software is pretty simple to use,
but the big disadvantage is that it locks you in to their software.
Also I>ve never done 4-layer stuff with them; I believe they>re also
kind of limited in that department. They>re great for quick-and-dirty
stuff though.

Regards,
-- Hauke D

On Jun 21, 4:19 pm, "Talal Itani" <tit...@verizon.net> wrote:

Hello,

I need to have a 4-layer board made, a prototype, 2 boards, nothing fancy.
I did some research in this newsgroup and I narrowed it down to Sierra Pro
Express, ExpressPCB, and AC Advanced Circuits. ï¿=3FDo you think I made the
right choice? ï¿=3FDo you have any recommendations? ï¿=3FI would like to receive the
board 3-5 days.

T.I.- Hide quoted text -

- Show quoted text -

I>ve used ExpressPCB for small projects before, but always 2-layer
stuff.
I>ve never had a problem with them, or their boards.

As for being "locked-in" to their software, for an extra $60 (last
time I checked), they will send you the Gerber files. From there, you
can import to many of the other programs avail.

Also, I recall hearing a while ago that a lot of these PCB prototype
houses are all built at the same place anyway. So, while you might
see 10 different company names (i.e., resellers), the boards
themselves all come from the same place. Sorry, I don>t remember the
names of the companies involved, and don>t know whether ExpressPCB is
one of them.

-mpm
ExpressPCB stuff comes from Mulino OR and at one time i knew the name
of the "parent" company that will do much "fancier" boards.

Don>t mix up ExpressPCB and PCB Express. The latter is a division of[/quote]
Sunstone, which builds boards in Mulino, Oregon. Sunstone gives me good
boards and I live close enough that the free UPS ground shipping gets me
boards the day after shipment. Sunstone also has their own free PCB
suite, PCB123.
http://www.pcb123.com/

I now order all my PCBs from Sunstone, so I>m a biased reporter. I>ve
been a fan of theirs since their customer service techs helped me
through some problems with an older, low-cost layout suite. They>re
still helping me through some problems with bigger 4-layers boards
since I>ve converted to PADS.

Mark Borgerson

mpm · Guest

On Jun 29, 5:34ï¿½pm, JeffM <jef...@email.com> wrote:
[quote]Mark Borgerson wrote:
Don>t mix up ExpressPCB and PCB Express.
The latter is a division of Sunstone[...]
Sunstone also has their own free PCB suite, ï¿½PCB123.

Pad2Pad, ExpressPCB, & PCB123 are all essentially the same thing.
They are all lock-in-ware.
Their output is NOT portable between fab houses.
None of them produce Gerbers.
[/quote]
Jeff - your information is incorrect.
For $60, ExpressPCB will definitely send you a Gerber file.
I know this from first hand experience. (The others mentioned also
might, but I can>t say)

I also concur that it is not the best approach if you do enough boards
to justify "better" schematic capture / PCB layout software (i.e., in-
house). But if you want to port the boards to production fabrication
(offshore), you certainly can obtain Gerbers from ExpressPCB.

-mpm

JeffM · Guest

mpm wrote:
[quote]JeffM wrote:
Pad2Pad, ExpressPCB, & PCB123 are all essentially the same thing.
They are all lock-in-ware.
Their output is NOT portable between fab houses.
None of them produce Gerbers.

Jeff - your information is incorrect.

Thank you for interpolating my post.[/quote]
I assure you that was not necessary.

I repeat: This "free" software does not *PRODUCE* Gerbers.
If you use it, you are LOCKED IN to a single fab house.

What I am saying is that to call itself an ECAD Package,
software should be able to generate Gerbers ON ITS OWN.

What you are describing
meets the classic definition of CRIPPLEWARE.

[quote]For $60, ExpressPCB will definitely send you a Gerber file.

I did NOT say there was no way to PURCHASE Gerbers.[/quote]
....AND PAY *AGAIN* AFTER THE SLIGHTEST CHANGE.

If that>s what YOU want, fine.
Full disclosure for the other folks is another thing.
Most people want to know what the cards up the sleeve are.
..
..
....and it appears you STILL haven>t read this:
http://groups.google.com/group/sci.electronics.design/browse_frm/thread/ffb3958a0de506f9?q=instead-click-on+THAT-*-link+*-Reply-at-the-bottom-*-*-*+DO-NOT+More.Options+blockquoting+other.people>s.sigs+weird-looking.posts

Jamie · Guest

w_tom wrote:

[quote]You still don>t get it. Voltage between line and neutral -
especially if using a plug-in protector - is near zero. Typically
well below what internal protection in any appliance does. Common
mode voltage (whether plug-in protector exists or not) is the 8000
volts destructively across an adjacent appliance - Page 42 Figure 8.
How many sources must note this because you get it? Lightning seeks
earth ground. It finds a path to earth destructively via the
appliance. What is that thousands of volts? While you discuss trivial
hundred voltage surges that harm nothing, those thousands of volts is
common mode - it seeks earth ground.

Characteristic impedance is not relevant. Why do you confuse
characteristic impedance with wire impedance that is completely
different? Current is in the same direction on one or all wires -
seeking earth ground. Therefore characteristic impedance obviously is
not relevant. Why do responsible sources that discuss surge
protection not discuss characteristic impedance? It obviously is not
relevant.

An MOV shunting (connecting, conducting) 150 volts between two wires
means either the MOV conducts no current (because a voltage is same on
both wires) or the MOV simply provides a surge more paths to find
earth ground destructively via the adjacent appliance. An MOV at the
appliance is for surges that typically don>t overwhelm protection
already inside all appliances.

Why do telcos not use your MOV solution? It does not provide
protection from surges that typically cause damage AND that surge it
would protect from what is also made irrelevant by the 'whole house'
protector. Yes, the 'whole house' protector is protection from all
types of surges. A more expensive plug-in protector protects from one
type of surge that typically causes no damage.

Telcos are not into enriching plug-in protector manufacturers.
Telcos need protection that works. That means a properly earthed
'whole house' protector on each incoming wire and no plug-in
protectors. At what point do you claim to be smarter than telcos all
over the world?

Sigh - you still don>t get it. There is no responsible source
citing what you have been posting. The Electrical Engineering Times
articles are entitled "Protecting Electrical Devices from Lightning
Transients". Why do they discuss earthing and completely ignore plug-
in protectors? Look at the title. EE Times does not promote popular
myths. Why do those articles discuss wire impedance (which is not
characteristic impedance)? Because effective protectors require low
impedance earthing. How many sources need be cited before John Fields
finally grasps the critical importance of low impedance earthing?
Even three IEEE Standards note what provides protection from typically
destructive surges - earth ground.

John Fields posts:

protection of the appliance ... isn>t the common mode
voltage on the cable conductors, it>s the voltage
between line and neutral.

No John. Voltage between line and neutral is near zero as a
destructive surge seeks earth ground (ie 8000 volts destructively) on
one or all of those wires. To promote grossly undersized and
obscenely overpriced plug-in protectors, then what is hyped to the
naive? Some irrelevant hot to neutral voltage - made irrelevant by
protection already inside appliances and also by a 'whole house'
protector.

Protection has always been about voltage between each wire and
earth. That protection also make voltage between hot and neutral
trivial. Effective surge protection means protection inside every
appliance is not overwhelmed. Protection not found in and not even
claimed by numeric specs for $25 or $150 plug-in protectors.

John - this is not rocket science. This was implemented even 100
years ago. After 100 years they are dumb and you know better? You
still don>t get it. Why do telcos not do what you have posted?
Effective protection is required. A protector is only as effective as
its earth ground. Same principle even applies to lightning rods.
Why do you have a problem with such well proven principles?

John Fields posted:

Look at the subject line to learn why all your prattle about earth
ground is immaterial.

And view an earliest reply. Solution is not three wire
receptacles. Solution is earthing the breaker box to meet and exceed
post 1990 electrical code and one 'whole house' protector. Less
expensive than plug-in protectors. No three wire receptacles
required. Protection that is tens or 100 times less money per
protected appliance. Why do you promote plug-in protectors when even
the OP describes what plug-in protectors cannot be used on - two wire
receptacles? Why do you keep posting what is completely irrelevant to
the OP>s question?

Orange County FL was suffering damage to emergency response
facilities. How was surge damage eliminated? Plug-in protectors? Of
course not. Emergency facilities needed protection - not a myth.
Orange county fixed the reason for surge damage - earthing:
http://www.psihq.com/AllCopper.htm

A surge protector is only as effective as its earthing. How many
sources say this? Instead John Fields even confuses wire impedance
with characteristic impedance. A protector is only as effective as
its earth ground - where surge energy must be harmlessly dissipated.
Why do you repeat the myth promoted by retail salesmen? Where
effective protection is installed, protectors make that short (ie
'less than 10 foot') connection to a single point earth ground. Where
scams are promoted, well, how is that protector (that you promote)
acceptable on the OP>s two wire receptacles? It>s not.

On Jun 29, 9:36 am, John Fields <jfie...@austininstruments.com> wrote:

But, what>s important is that, at the appliance, the TVS clamps the
voltage between line and neutral to 150V regardless of the line
impedance.

Likewise, if another appliance at another outlet was protected by a
TVS then it would be irrelevant what common mode voltage existed on
either set, the voltage from line to neutral would still be limited to
150V.
...
Not really.

Since the conductors in the cable run parallel to each other the cable
is actually a transmission line and will exhibit some characteristic
impedance. Here:
http://en.wikipedia.org/wiki/Characteristic_impedance
...

Sigh... You _still_ don>t get it.

What matters, as far as protection of the appliance is concerned,
isn>t the common mode voltage on the cable conductors, it>s the
voltage between line and neutral.

Which is why TVSs are effective, since they clamp that voltage to some
safe maximum which the appliance can stand momentarily.
...

Ok, Another to add to my black list.[/quote]

--
"I>d rather have a bottle in front of me than a frontal lobotomy"

"Daily Thought:

SOME PEOPLE ARE LIKE SLINKIES. NOT REALLY GOOD FOR ANYTHING BUT
THEY BRING A SMILE TO YOUR FACE WHEN PUSHED DOWN THE STAIRS.
http://webpages.charter.net/jamie_5"

John Fields · Guest

On Sun, 29 Jun 2008 16:16:10 -0700 (PDT), w_tom <w_tom1@usa.net>
wrote:

---
Nothing of any consequence.

Yup, yer a loon...

JF

Paul E. Schoen · Guest

"JeffM" <jeffm_@email.com> wrote in message
news:ec31dfd9-b52f-4894-8ada-b0c9cc49b67c@t54g2000hsg.googlegroups.com...
[quote]mpm wrote:
JeffM wrote:
Pad2Pad, ExpressPCB, & PCB123 are all essentially the same thing.
They are all lock-in-ware.
Their output is NOT portable between fab houses.
None of them produce Gerbers.

Jeff - your information is incorrect.

Thank you for interpolating my post.
I assure you that was not necessary.

I repeat: This "free" software does not *PRODUCE* Gerbers.
If you use it, you are LOCKED IN to a single fab house.

What I am saying is that to call itself an ECAD Package,
software should be able to generate Gerbers ON ITS OWN.

What you are describing
meets the classic definition of CRIPPLEWARE.

For $60, ExpressPCB will definitely send you a Gerber file.

I did NOT say there was no way to PURCHASE Gerbers.
...AND PAY *AGAIN* AFTER THE SLIGHTEST CHANGE.

If that>s what YOU want, fine.
Full disclosure for the other folks is another thing.
Most people want to know what the cards up the sleeve are.
[/quote]
If the ExpressPCB package was really top-notch, and offered for free, I
could understand them locking you in without Gerbers. But I seem to
remember it was mostly a drafting package that had very limited
capabilities compared to (of course) PADS, but there were other free or
very inexpensive packages that had better capabilities and actually created
Gerbers.

I tried to check pricing from PCBexpress, and I got this:

"Warning: mysql_pconnect(): Can>t connect to local MySQL server through
socket '/var/lib/mysql/mysql.sock' (2) in
/home/pcbexpress.com/html/products/utls.inc.php on line 25
We>re sorry...please try this process again later."

I>d like to compare them to pcbfabexpress. I guess I>ll "try again later".

Paul

mpm · Guest

On Jun 29, 11:10ï¿½pm, JeffM <jef...@email.com> wrote:
[quote]mpm wrote:
JeffM wrote:
Pad2Pad, ExpressPCB, & PCB123 are all essentially the same thing.
They are all lock-in-ware.
Their output is NOT portable between fab houses.
None of them produce Gerbers.

Jeff - your information is incorrect.

Thank you for interpolating my post.
I assure you that was not necessary.

I repeat: ï¿½This "free" software does not *PRODUCE* Gerbers.
If you use it, you are LOCKED IN to a single fab house.

What I am saying is that to call itself an ECAD Package,
software should be able to generate Gerbers ON ITS OWN.

What you are describing
meets the classic definition of CRIPPLEWARE.

For $60, ExpressPCB will definitely send you a Gerber file.

I did NOT say there was no way to PURCHASE Gerbers.
...AND PAY *AGAIN* AFTER THE SLIGHTEST CHANGE.

If that>s what YOU want, fine.
Full disclosure for the other folks is another thing.
Most people want to know what the cards up the sleeve are.
.
.
...and it appears you STILL haven>t read this:http://groups.google.com/group/sci.electronics.design/browse_frm/thre...
[/quote]
Jeff - What is your problem?
You gave out bad info. I corrected it. Get over it.

I personally used ExpressPCB, got the boards exactly the way I wanted
them, then turned around and got the Gerbers from ExpressPCB (for an
additional $60), and then proceeded to shop the high-volume production
boards overseas. (Using those same Gerbers).

So, explain how I was "locked-in". ?????

I am not so interested in correcting your statements (interpolating or
whatever), nor am I that interested in the nuance argument as to
whether the ExpressPCB directly produces a Gerber output (which I
never claimed, but you invented).

My only purpose here was to correct the post, so that other>s could
rely on the right information as they make their choices. I also did
not opine on whether the ExpressPCB route was any better or worse, or
less expensive than having your own high(er)-end program in house,
such as Orcad or whatever.

The bottom line is ExpressPCB can indeed (eventually) result in a
Gerber file that you can port between fabricators. This statement is
in direct contravention to your earler remark that:

And I quote:

[quote]They are all lock-in-ware.
Their output is NOT portable between fab houses.
None of them produce Gerbers.
[/quote]
Have a nice day.

-mpm

w_tom · Guest

On Jun 29, 8:43 pm, John Fields <jfie...@austininstruments.com> wrote:
[quote]Nothing of any consequence.
[/quote]
So John, where is any professional citation that says characteristic
impedance is relevant? Nothing.

Where is this professional citation that says common mode surges -
what lightning creates - are not typically destructive surges?
Nothing.

Where is this professional citation that says a hot to neutral surge
is not eliminated (reduced) by that same one 'whole house' protector?
Nothing.

Why is a peer reviewed front page article in a highly regarded
electrical engineering publication not relevant? Its title:
"Protecting Electrical Devices from Lightning Transients". John
somehow knows industry professionals are wrong?

You have even confused characteristic impedance with wire impedance.
Why do you ignore wire impedance and discuss irrelevant wire
resistance? Your denials are based only in insults?

Why does every telco install 'whole house' protectors and not waste
money on plug-in protectors? For better protection, why do telcos
locate protectors distant from electronics - up to 50 meters? For
better protection, why do telcos install even better earthing and
connect 'whole house' protectors as short as practicable to that
earthing? John says telcos are also loony?

And where is that plug-in protector spec that claims protection?
Oh. No plug-in protector will list protection from each type of
surge. But you know that plug-in protector is effective?

Where does John Fields post a solution for the OP whose building
only has two wire receptacles? You provide no useful answers.

OP>s solution is simple, more effective, and less expensive than
plug-in protectors. Similar to a solution implemented by all telcos,
commercial broadcasters, rocket launch facilities, and military
bases. A 'whole house' protector with breaker box earthing is
upgraded to post 1990 National Electrical Code standards. Complete
surge protection installed for about $1 per protected appliance.

Why does John Fields recommend using three wire power strip
protectors on two wire receptacles? How do John>s insults prove
science or assist the OP? John even denies lightning creates common
mode surges. A protector is only as effective as its earth ground as
noted by numerous above and responsible sources. Meanwhile, the OP
cannot use plug-in protectors. His best solution is the standard
solution used everywhere when surge damage is not acceptable.


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