Toshiba TV29C90 problem; Image fades to black...

[Michael Moroney]

Bruce in Bangkok <decypher_signature@signature.line> writes:

All distribution transformers, sometimes called "pole pigs", that I
have seen had some sort of voltage adjusting system, usually referred
to as taps. Usually they are an actual bolted "tap" and you open the
transformer and set the output voltage by making the proper tap
connection when the transformer is installed and frankly it is usually
ignored thereafter.

What I was talking about appear to be used to adjust for supplied voltage
(they're often used right after a stepdown transformer bank) or long
runs, which may produce somewhat variable voltages that need adjustment
at times.

The other "cans" you often see on poles are capacitors used to adjust
the power factor on some secondaries.

Around here, capacitors for power factor compensation are rectangular
boxes with two bushings on top, on poles, in banks of 3, 6 or sometimes 9.

Like the ones Phil mentioned, the cans I talked about hum.

 

[Michael Moroney]

phil-news-nospam@ipal.net writes:

The really strange thing is Brazil has 220 volts all around the country,
with 60 Hz in some parts and 50 Hz in others, and used to use the American
120 volt 2-blade outlet/plug with 220 volts (you can be in for a surprise
with that).

The Philippines uses 220V 60Hz with US-style 2 blade outlets as well.

 

[Michael Moroney]

phil-news-nospam@ipal.net writes:

The really strange thing is Brazil has 220 volts all around the country,
with 60 Hz in some parts and 50 Hz in others, and used to use the American
120 volt 2-blade outlet/plug with 220 volts (you can be in for a surprise
with that).

The Philippines uses 220V 60Hz with US-style 2 blade outlets as well.

 

In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void> wrote:

| ? <phil-news-nospam@ipal.net> ?????? ??? ??????
| news:g0f71q111lk@news3.newsguy.com...
|> In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void>
|> wrote:
|>
|> | Professional washing machines. One of my very first days 'in the field'
|> was
|> | to connect some of them. They have a large heating element, you can
|> connect
|> | it single phase, or 3 phase, it just heats up faster (of course) when
|> you
|> | connect it 3 phase. (they have a single phase motor, so it works also in
|> | pure 230 V).
|>
|> If it has 3 elements rated for 230 volts, with 3 separate connections that
|> would be to three separate phase for a three phase feed, and all connected
|> to the one phase for a single phase feed, then it should heat up at the
|> same
|> speed, while drawing three times the current (not accounting for the
|> motor).
|>
|> I don't know why it should heat up faster in three phase, or why you would
|> say "of course" about it. I would think it would heat up faster if you
|> took
|> it over to London and hooked it up to a 240 volt supply.
|>
| Maybe you connected with single phase just one element? The rest two
| remained unconnected? (3 230 volts elements, connected wye). I'm sure it
| heated up faster, in 3 phase connection.

You were the one who said "it just heats up faster (of course) when you
connect it 3 phase."

I would disagree.

But the fact that you said "(of course)" seems you presume that to be the
general case. Now your most recent comment at least acknowledges that if
not all elements are connected, it won't heat up as fast.

In the simple case, each of 3 elements is individually wired, so you have
a total of 6 leads. When connecting to three phase, one lead of each is
connected to neutral, and each of the other leads is connected to separate
phases. When connecting to single phase, they are all wired in parallel.
Both cases always involve one of the leads from each element connected to
neutral, so those 3 leads can be pre-connected together. So you could have
just 4 leads. The common neutral lead needs to be rated for all the current
together for it to be rated properly for single phase.

It should apply the same voltage (230V) to each element, and they should each
draw the same current. How would you believe this would be slower to heat?

If the 3 elements were wired _internally_ in star without a neutral lead,
it would still work fine on three phase as long as all elements were equal
impedance. But on single phase, you could only activate 2 of the elements,
and that would be 2 in series fed with 230 volts. You'd only get 1/6 the
power that way.

Are you assuming the elements would be wired that way? That would clearly
NOT be intended for single phase connection.

The 3 elements could be wired _internally_ in delta. In this case, these
would have to be 400V elements. Connecting 2 leads to 230 volts would still
give you only 1/6 the power (but more evenly distributed in this case).

So what is the situation that makes _you_ believe that 3 elements connected
to single phase _will_ draw less power to heat the water than when connected
to three phase?

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void> wrote:

| ? <phil-news-nospam@ipal.net> ?????? ??? ??????
| news:g0f71q111lk@news3.newsguy.com...
|> In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void>
|> wrote:
|>
|> | Professional washing machines. One of my very first days 'in the field'
|> was
|> | to connect some of them. They have a large heating element, you can
|> connect
|> | it single phase, or 3 phase, it just heats up faster (of course) when
|> you
|> | connect it 3 phase. (they have a single phase motor, so it works also in
|> | pure 230 V).
|>
|> If it has 3 elements rated for 230 volts, with 3 separate connections that
|> would be to three separate phase for a three phase feed, and all connected
|> to the one phase for a single phase feed, then it should heat up at the
|> same
|> speed, while drawing three times the current (not accounting for the
|> motor).
|>
|> I don't know why it should heat up faster in three phase, or why you would
|> say "of course" about it. I would think it would heat up faster if you
|> took
|> it over to London and hooked it up to a 240 volt supply.
|>
| Maybe you connected with single phase just one element? The rest two
| remained unconnected? (3 230 volts elements, connected wye). I'm sure it
| heated up faster, in 3 phase connection.

You were the one who said "it just heats up faster (of course) when you
connect it 3 phase."

I would disagree.

But the fact that you said "(of course)" seems you presume that to be the
general case. Now your most recent comment at least acknowledges that if
not all elements are connected, it won't heat up as fast.

In the simple case, each of 3 elements is individually wired, so you have
a total of 6 leads. When connecting to three phase, one lead of each is
connected to neutral, and each of the other leads is connected to separate
phases. When connecting to single phase, they are all wired in parallel.
Both cases always involve one of the leads from each element connected to
neutral, so those 3 leads can be pre-connected together. So you could have
just 4 leads. The common neutral lead needs to be rated for all the current
together for it to be rated properly for single phase.

It should apply the same voltage (230V) to each element, and they should each
draw the same current. How would you believe this would be slower to heat?

If the 3 elements were wired _internally_ in star without a neutral lead,
it would still work fine on three phase as long as all elements were equal
impedance. But on single phase, you could only activate 2 of the elements,
and that would be 2 in series fed with 230 volts. You'd only get 1/6 the
power that way.

Are you assuming the elements would be wired that way? That would clearly
NOT be intended for single phase connection.

The 3 elements could be wired _internally_ in delta. In this case, these
would have to be 400V elements. Connecting 2 leads to 230 volts would still
give you only 1/6 the power (but more evenly distributed in this case).

So what is the situation that makes _you_ believe that 3 elements connected
to single phase _will_ draw less power to heat the water than when connected
to three phase?

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

[Jim Yanik]

James Sweet <jamessweet1@trashmail.net> wrote in
news:e13Xj.11700$mc1.10406@trndny08:

Sam Goldwasser wrote:
Anyone ever seen this? It's a cute little frequency counter that
is supposed to go to 1.3 GHz, but only the 10 MHz and 60 MHz ranges
work. The 1.3 GHz range is either non-responsive or erratic.

There's a house numbered chip, which may be the prescaler: 2-8758-229
with 274-227 below that.

Any info appreciated.

Thanks!




I assume you've tried Ramsey?

Is this the same company that makes all the kits?

I took high school electronics shop with a John Ramsey,Kenmore,NY.
He was making FM wireless mikes at the time.

--
Jim Yanik
jyanik
at
kua.net

 

[Don Kelly]

<phil-news-nospam@ipal.net> wrote in message
news:g0ggfm11s3j@news5.newsguy.com...

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| If I read you correctly, you want to use a second secondary (lower power
| rating) which is tapped and put in series with the main secondary. Now
once
| you do this, you have in effect a single secondary with taps just as in
a
| conventional tapped secondary. Sure the "tapped section" is lower power-
| because it is a lower voltage but it still has to handle the same
current.
| Nothing is gained.
| The problem in tap changing is not "power" but the current being
switched.

No, that is not what I tried to explain. I'll try again:

The main transformer would have 2 secondaries. These 2 secondaries are
NOT
wired in series with each other. The smaller of these secondaries will
have
taps. The tapped smaller secondary feeds another smaller transformer.
The
larger secondary of the main transformer, and the only secondary of the
smaller
auxiliary transformer, would be wired in series. So the taps are only
dealing
with the current of the lower power "tapping section". The smaller
secondary
of the main transformer, and the primary of the auxiliary transformer, can
be
wired for whatever voltage/current works out best.


| In either case the voltage driving short circuit current on tap changing
is
| that between taps
| Delta V =A(delta n) Delta Z =B(delta n)^2. where delta n is the change
in
| turns between taps. The short circuit current on such a change will be
| proportional to 1/(delta n).
|
| If you want fine control, then you could go to sliding carbon brush as
in a
| variac. The first idea of a separate transformer feeding a variac will
not
| solve the "too low" voltage problem of the variac because you are still
| dealing with an autotransformer.

In that first scheme, adjusting the variac to the lowest voltage would be
reducing the voltage contributed by the boost transformer. There is still
the original supply voltage going around the variac, "plus" (actually
minus)
the buck voltage (to select the range I want). Since the variac is an
autotransformer itself, it merely feeds the primary of the boost
transformer.
Note that in this case the "boost" transformer is wired as an isolation
transformer. I should have mentioned that. If needed, I guess I could
draw
some ASCII diagrams or try to get something made graphically (all the
tools
I have to do that suck, except for Visio which needs Windows to run and I
don't have a spare machine to do that at the moment).
---------------------------------

Actually I see added complexity without any gain. You may be doing the tap
changing at a lower current and higher voltage but there will be no "lower
Power" switching but there will be more losses during operation even when
not changing taps. I suspect the complexity and the losses together would
cost more than a conventional tap changer. There are some circuit factors
involved which may be undesirable but I haven't done a proper analysis.
--

Don Kelly dhky@shawcross.ca
remove the X to answer
----------------------------

>

 

[Don Kelly]

<phil-news-nospam@ipal.net> wrote in message
news:g0ggfm11s3j@news5.newsguy.com...

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| If I read you correctly, you want to use a second secondary (lower power
| rating) which is tapped and put in series with the main secondary. Now
once
| you do this, you have in effect a single secondary with taps just as in
a
| conventional tapped secondary. Sure the "tapped section" is lower power-
| because it is a lower voltage but it still has to handle the same
current.
| Nothing is gained.
| The problem in tap changing is not "power" but the current being
switched.

No, that is not what I tried to explain. I'll try again:

The main transformer would have 2 secondaries. These 2 secondaries are
NOT
wired in series with each other. The smaller of these secondaries will
have
taps. The tapped smaller secondary feeds another smaller transformer.
The
larger secondary of the main transformer, and the only secondary of the
smaller
auxiliary transformer, would be wired in series. So the taps are only
dealing
with the current of the lower power "tapping section". The smaller
secondary
of the main transformer, and the primary of the auxiliary transformer, can
be
wired for whatever voltage/current works out best.


| In either case the voltage driving short circuit current on tap changing
is
| that between taps
| Delta V =A(delta n) Delta Z =B(delta n)^2. where delta n is the change
in
| turns between taps. The short circuit current on such a change will be
| proportional to 1/(delta n).
|
| If you want fine control, then you could go to sliding carbon brush as
in a
| variac. The first idea of a separate transformer feeding a variac will
not
| solve the "too low" voltage problem of the variac because you are still
| dealing with an autotransformer.

In that first scheme, adjusting the variac to the lowest voltage would be
reducing the voltage contributed by the boost transformer. There is still
the original supply voltage going around the variac, "plus" (actually
minus)
the buck voltage (to select the range I want). Since the variac is an
autotransformer itself, it merely feeds the primary of the boost
transformer.
Note that in this case the "boost" transformer is wired as an isolation
transformer. I should have mentioned that. If needed, I guess I could
draw
some ASCII diagrams or try to get something made graphically (all the
tools
I have to do that suck, except for Visio which needs Windows to run and I
don't have a spare machine to do that at the moment).
---------------------------------

Actually I see added complexity without any gain. You may be doing the tap
changing at a lower current and higher voltage but there will be no "lower
Power" switching but there will be more losses during operation even when
not changing taps. I suspect the complexity and the losses together would
cost more than a conventional tap changer. There are some circuit factors
involved which may be undesirable but I haven't done a proper analysis.
--

Don Kelly dhky@shawcross.ca
remove the X to answer
----------------------------

>

 

[Don Kelly]

----------------------------
<phil-news-nospam@ipal.net> wrote in message
news:g0ghuf41s3j@news5.newsguy.com...

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| Just a bitch that we have dealt with before:
|
| Phil- please realize that 207.846096....... is meaningless except that
it is
| "about 208". 208V is correct to 3 significant figures which is actually
| better than one can assume to be true in practice. If the voltage line
to
| neutral is actually 120.V (note the decimal) then we have 3 significant
| digits implying something between 119.5 Vand 120.5.V
| Then all you can truly claim is 208.V
| If it is 120.0V then there is reason to assume 208.0 V but no more
decimals
| than that.
| If you have a meter which gives you 120.000000V with less than 1 part in
120
| million error then you can claim 207.846097V for line to line voltage
Do
| you have such a meter?
|
| Engineering and physics students who ignore the principle of
"significant
| digits" lose marks for this "decimal inflation".
|
| Sure- you can let the calculator carry the extra digits (as it will do
| internally) but accepting these as gospel truth to the limit of the
| calculator or computer display is simply not on as you can't get better
| accuracy from a calculation than the accuracy of the original data
(actually
| you will lose a bit). All that you get rid of is round off errors in
| calculations.
|
| Since, as you say, precise voltage is not really practical, then
| multi-decimal point numbers are meaningless. If we say 120V +/-10% then
we
| are talking about 108-132V which for line to line becomes 187-229V
(average
| 208V) and any extra decimal points don't mean anything.

You didn't notice the I put on the number?

We've been over this. I know the practice of significant digits, and how
the voltages are designated (two different reasons you can get 208). I do
follow the practice of carrying exactly the result of calculations into
other calculations. I also use over significance in comparison of
numbers.

But I also know that rounding is a form of noise. So I avoid it until the
time I end up with the final result. So if I multiply 120 by the square
root of three I do get a number like 207.84609690826527522329356 which is
either carried as-is into the next calculation, or rounded if it is the
final answer. If some other strange calculation happens to give me the
value 207.84609690826527522329356 then I know it is effectively equivalent
to 120 times the square root of three in some way. But if what I get is
208.455732193971783228 then I know it has nothing to do with 120 times the
square root of three, even though it, too, would end up as 208 if rounded
to 3 significant digits.

When it comes to _measured_ amounts, as opposed to synthetic ones, then
the
significance rules dictate how to round the results. With synthetic
numbers
(e.g. numbers I can just pick), I can also pick the rounding rules for the
final results. But if I don't know that the calculations are done (e.g. I
am not merely giving a designation for a voltage system), where someone
else
may take those numbers and do more calculations and round the results,
then
I do use more significance. But that is no different to me than just
carrying
that number from one calculation stage to another.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to
ignorance |
| by the abuse department, bellsouth.net is blocked. If you post
to |
| Usenet from these places, find another Usenet provider ASAP.
|
| Phil Howard KA9WGN (email for humans: first name in lower case at
ipal.net) |
-------------------------

Fair enough- but still overkill. For the bulk of the calculations that one
does, single precision is more than adequate. Anything more, even for
comparison of numbers is really fluff.
I simply set my display to show the desired sig figs and let the calculator
deal with the rest in its normal internal mode. I don't want to see the
extra digits, or , if I do, 1 or 2 is sufficient. Ditto with the computer.
Only if I am dealing with ill conditioned sets of simultaneous equations ,
will I really require double precision.
--

Don Kelly dhky@shawcross.ca
remove the X to answer

 

[Don Kelly]

----------------------------
<phil-news-nospam@ipal.net> wrote in message
news:g0ghuf41s3j@news5.newsguy.com...

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| Just a bitch that we have dealt with before:
|
| Phil- please realize that 207.846096....... is meaningless except that
it is
| "about 208". 208V is correct to 3 significant figures which is actually
| better than one can assume to be true in practice. If the voltage line
to
| neutral is actually 120.V (note the decimal) then we have 3 significant
| digits implying something between 119.5 Vand 120.5.V
| Then all you can truly claim is 208.V
| If it is 120.0V then there is reason to assume 208.0 V but no more
decimals
| than that.
| If you have a meter which gives you 120.000000V with less than 1 part in
120
| million error then you can claim 207.846097V for line to line voltage
Do
| you have such a meter?
|
| Engineering and physics students who ignore the principle of
"significant
| digits" lose marks for this "decimal inflation".
|
| Sure- you can let the calculator carry the extra digits (as it will do
| internally) but accepting these as gospel truth to the limit of the
| calculator or computer display is simply not on as you can't get better
| accuracy from a calculation than the accuracy of the original data
(actually
| you will lose a bit). All that you get rid of is round off errors in
| calculations.
|
| Since, as you say, precise voltage is not really practical, then
| multi-decimal point numbers are meaningless. If we say 120V +/-10% then
we
| are talking about 108-132V which for line to line becomes 187-229V
(average
| 208V) and any extra decimal points don't mean anything.

You didn't notice the I put on the number?

We've been over this. I know the practice of significant digits, and how
the voltages are designated (two different reasons you can get 208). I do
follow the practice of carrying exactly the result of calculations into
other calculations. I also use over significance in comparison of
numbers.

But I also know that rounding is a form of noise. So I avoid it until the
time I end up with the final result. So if I multiply 120 by the square
root of three I do get a number like 207.84609690826527522329356 which is
either carried as-is into the next calculation, or rounded if it is the
final answer. If some other strange calculation happens to give me the
value 207.84609690826527522329356 then I know it is effectively equivalent
to 120 times the square root of three in some way. But if what I get is
208.455732193971783228 then I know it has nothing to do with 120 times the
square root of three, even though it, too, would end up as 208 if rounded
to 3 significant digits.

When it comes to _measured_ amounts, as opposed to synthetic ones, then
the
significance rules dictate how to round the results. With synthetic
numbers
(e.g. numbers I can just pick), I can also pick the rounding rules for the
final results. But if I don't know that the calculations are done (e.g. I
am not merely giving a designation for a voltage system), where someone
else
may take those numbers and do more calculations and round the results,
then
I do use more significance. But that is no different to me than just
carrying
that number from one calculation stage to another.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to
ignorance |
| by the abuse department, bellsouth.net is blocked. If you post
to |
| Usenet from these places, find another Usenet provider ASAP.
|
| Phil Howard KA9WGN (email for humans: first name in lower case at
ipal.net) |
-------------------------

Fair enough- but still overkill. For the bulk of the calculations that one
does, single precision is more than adequate. Anything more, even for
comparison of numbers is really fluff.
I simply set my display to show the desired sig figs and let the calculator
deal with the rest in its normal internal mode. I don't want to see the
extra digits, or , if I do, 1 or 2 is sufficient. Ditto with the computer.
Only if I am dealing with ill conditioned sets of simultaneous equations ,
will I really require double precision.
--

Don Kelly dhky@shawcross.ca
remove the X to answer

 

[bz]

NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are both
measured in pounds in the english system.

Metric is 'much simpler' with grams(mass) and newtons(force).





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[charles]

In article <MPG.2297621d47f3215f989c18@news.individual.net>,
krw <krw@att.bizzzzzzzzzz> wrote:

In article <Xns9AA04BA6F2C05WQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are both
measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

The 'Stone' is a unit of mass, not "The unit of mass"

All the engineering I ever learned in the British (Imperial) system used
pounds.

Metric is 'much simpler' with grams(mass) and newtons(force).

No - the modern Metric system uses the kilogramme as its fundamental unit.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

 

[charles]

In article <MPG.2297621d47f3215f989c18@news.individual.net>,
krw <krw@att.bizzzzzzzzzz> wrote:

In article <Xns9AA04BA6F2C05WQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are both
measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

The 'Stone' is a unit of mass, not "The unit of mass"

All the engineering I ever learned in the British (Imperial) system used
pounds.

Metric is 'much simpler' with grams(mass) and newtons(force).

No - the modern Metric system uses the kilogramme as its fundamental unit.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

 

[bz]

krw <krw@att.bizzzzzzzzzz> wrote in news:MPG.2297621d47f3215f989c18
@news.individual.net:

In article <Xns9AA04BA6F2C05WQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are both
measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

Metric is 'much simpler' with grams(mass) and newtons(force).

Evidently *you* think the "English" system is too complicated. ;-)

http://www.engineeringtoolbox.com/mass-weight-d_589.html

I don't think any of them are 'too complicated'.
It is easy enough to convert from one to another.

However, FAILURE to convert has been known to cause problems, such as a
Mars mission that crashed because the wrong units were used.

http://www.cnn.com/TECH/space/9909/30/mars.metric/




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

krw <krw@att.bizzzzzzzzzz> wrote in news:MPG.2297621d47f3215f989c18
@news.individual.net:

In article <Xns9AA04BA6F2C05WQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are both
measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

Metric is 'much simpler' with grams(mass) and newtons(force).

Evidently *you* think the "English" system is too complicated. ;-)

http://www.engineeringtoolbox.com/mass-weight-d_589.html

I don't think any of them are 'too complicated'.
It is easy enough to convert from one to another.

However, FAILURE to convert has been known to cause problems, such as a
Mars mission that crashed because the wrong units were used.

http://www.cnn.com/TECH/space/9909/30/mars.metric/




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[charles]

In article <482dd43c$0$3362$4c368faf@roadrunner.com>, Anthony Matonak
<anthonym40@nothing.like.socal.rr.com> wrote:

charles wrote:
krw <krw@att.bizzzzzzzzzz> wrote:
bz+ser@ch100-5.chem.lsu.edu says...
It is necessary to distinguish between mass and force but they are
both measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

The 'Stone' is a unit of mass, not "The unit of mass"

All the engineering I ever learned in the British (Imperial) system
used pounds.

I always thought the British pound was a unit of currency.

cleverly, we use the same word for two different things to confuse
foreigners.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

 

[charles]

In article <MPG.2297afa66f89b465989c1a@news.individual.net>,
krw <krw@att.bizzzzzzzzzz> wrote:

In article <4fa0724480charles@charleshope.demon.co.uk>,
charles@charleshope.demon.co.uk says...
In article <MPG.2297621d47f3215f989c18@news.individual.net>,
krw <krw@att.bizzzzzzzzzz> wrote:
In article <Xns9AA04BA6F2C05WQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are
both measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

The 'Stone' is a unit of mass, not "The unit of mass"

It is *the* unit of mass. The pound-mass is a recent abortion.

All the engineering I ever learned in the British (Imperial) system used
pounds.

You must be a kid.

No - 68!!!

Metric is 'much simpler' with grams(mass) and newtons(force).

No - the modern Metric system uses the kilogramme as its fundamental
unit.

Only if you spell funny.

Even in 1961 the MKS system was the norm.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

 

[Don Kelly]

"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in message
news:482e26af$0$5117$4c368faf@roadrunner.com...

"krw" <krw@att.bizzzzzzzzzz> wrote in message
news:MPG.2297afa66f89b465989c1a@news.individual.net...
In article <4fa0724480charles@charleshope.demon.co.uk>,
charles@charleshope.demon.co.uk says...
In article <MPG.2297621d47f3215f989c18@news.individual.net>,
krw <krw@att.bizzzzzzzzzz> wrote:
In article <Xns9AA04BA6F2C05WQAHBGMXSZHVspammote@130.39.198.139>,
bz+ser@ch100-5.chem.lsu.edu says...
NameNotImportant <Dont@sk.com> wrote in
news:CfWdnQNR9cg0wbHVnZ2dnUVZ_rTinZ2d@earthlink.com:

lbm?

I'm not sure on your units.

pounds (mass), lbm, as opposed to pounds (force), lbf, or lb.

It is necessary to distinguish between mass and force but they are
both
measured in pounds in the english system.

The "English" system uses the "stone" as the measurement of mass.
The pound ('lb') is the unit of *FORCE*.

The 'Stone' is a unit of mass, not "The unit of mass"

It is *the* unit of mass. The pound-mass is a recent abortion.


If you call the past 100 years or so, 'recent'. I myself have text-books
from the '50's that use this 'recent abortion' as you call it.

Considering the separation of force and mass was first worked out *after*
the original 'pound' for weight was in common use, it was necessary to
separate which 'kind' of 'pound' was being talked about. The one that
represents how much *force* is being applied to something, or the one that
describes how much resistance to acceleration something has.

But for a long time a 'pound' of something was a certain amount of
mass -or- the force applied to a surface by placing that certain amount of
mass on it (such as used in 'dead-weight' testers for pressure
instruments).

In a few obscure bits of engineering, you can even find the term
'kilograms of force' used. Obviously that is the force applied by placing
a kilogram of mass on top of something. You can even find some pressure
gauges calibrated to read 'kg/cm^2'. Proof that you can mess up things
even with the metric system. ;-)

I'm not sure how old the 'stone' is, but I suspect it too was around
before we knew the difference between force and mass. Stone is common in
UK still, but it never caught on in the colonies, even as far back as
colonial days when 'hundredweight' and 'long ton' were in common usage.

Trouble with pound-mass (lbm) and pound-force (lbf) is that to make F=MA
work out, you need to keep another 'conversion factor', the dreaded
g-sub-c (g-sub-c = 32.2 lbm-ft / lbf-s^2), around and figure out when to
throw that into the mix.

daestrom

In the early '50's there were two other units around- the poundal (1/g
pounds force) or a mass called a slug (g pounds mass). Learning mechanics
with these units (don't use them together)is worse than working in the
stone, furlong, fortnight set of units.
The poundal was introduced in 1879 as part of the "english set of units"
(Wikipedia is sometimes useful).
--

Don Kelly dhky@shawcross.ca
remove the X to answer
----------------------------
>

 

[bz]

"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in
news:482e26af$0$5117$4c368faf@roadrunner.com:

Trouble with pound-mass (lbm) and pound-force (lbf) is that to make F=MA
work out, you need to keep another 'conversion factor', the dreaded
g-sub-c (g-sub-c = 32.2 lbm-ft / lbf-s^2), around and figure out when to
throw that into the mix.

Really gets to be fun when working with things like foot-pounds,
as in torque, angular momentum, and the pressure due to a certain depth of
water.

Trying to remember when the pounds are mass and when they are force gets
to be fun.



--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[charles]

In article <MTsXj.145740$Cj7.35522@pd7urf2no>,
Don Kelly <dhky@shaw.ca> wrote:

In the early '50's there were two other units around- the poundal (1/g
pounds force) or a mass called a slug (g pounds mass). Learning
mechanics with these units (don't use them together)is worse than
working in the stone, furlong, fortnight set of units. The poundal was
introduced in 1879 as part of the "english set of units" (Wikipedia is
sometimes useful).

I certainly remember the poundal.

The various old english measures: chain, rod, quarter, peck, etc, were, of
course, very useful to teach children arithmetic since they all came with
different bases.

and of course you can measure viscosity in Acres per year - if you want to.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11