I have never understood why both ends of the track are connected in a circuit. Can anyone enlighten me?

On 05/01/17 00:58, DerbyBorn wrote:
I have never understood why both ends of the track are connected in a circuit. Can anyone enlighten me?

in a rheostat they are not. You are thinking of a potentiometer.

See, I don't understand!

"DerbyBorn" wrote in message
...
I have never understood why both ends of the track are connected in a
circuit. Can anyone enlighten me?

Very often the slider is connected to one end of the track. Then, if the
slider goes open circuit the variable resistor will produce the value of the
track. Otherwise the value would be infinite.

In article ,
DerbyBorn wrote:
I have never understood why both ends of the track are connected in a
circuit. Can anyone enlighten me?


They're not always. But if say a volume control, it wouldn't go to zero if
one side wasn't connected to ground.

--
*Venison for dinner again? Oh deer!*

Dave Plowman London SW
To e-mail, change noise into sound.

On Wed, 4 Jan 2017 15:17:12 -0800 (PST), DerbyBorn
wrote:

See, I don't understand!

A rheostat generally just adds (variable) resistance into a circuit
and the surplus energy is absorbed via that.

So say you put one in series with a battery charger you could reduce
the charge current by using the resistance in the rheostat to 'waste'
(in heat) what you didn't want going to the battery (voltage dropped
across the resistor), ranging from max current (no resistance) to
minimum current (maximum resistance).

A potentiometer generally has both ends connected to a circuit so that
you get a variable potential divider (so works more on voltage /
potential than current). So typically, one end of the pot might be
connected to the supply rail (say 5V) and the other end to ground (OV)
and therefore the voltage seen at the wiper will range from around 0V
to around 5V, as you turn the 'pot' from one end to the other.

Cheers, T i m

"DerbyBorn" wrote in message
...
I have never understood why both ends of the track are connected in a
circuit. Can anyone enlighten me?

Basically because that ensures that even if the wiper
isnt always in contact with the track all the time, the
worst you get is the same result as with the wiper at
one end of the track.

On Wednesday, 4 January 2017 22:58:21 UTC, DerbyBorn wrote:
I have never understood why both ends of the track are connected in a circuit. Can anyone enlighten me?

It can be the differnce between varaible resistor and a potentiometer, but sometimes a componet will be used as a varible resistor but have all 3 'terminals' used this can help reduce 'noise' and in some cases I've heard to reduce reflections in some circuits.

Rheostats seems to be the term applied to high power variable resistors that most people would refer to as pots nowadays.
I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

On 04/01/2017 22:58, DerbyBorn wrote:
I have never understood why both ends of the track are connected in a circuit. Can anyone enlighten me?

The main reason is to avoid leaving the unused end of the potentiometer
floating and so potentially acting like an aerial for RF noise.

It also maintains a worst case impedance of Rmax instead of open circuit
if the wiper happens to have a dead spot somewhere.

--
Regards,
Martin Brown

On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.


NT

On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.


NT

More or less utter ********

In article ,
The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.


NT

More or less utter ********

all resistors, fixed and variable use a zigzag symbol. Variable resistors
simply had an arrow added.

--
from KT24 in Surrey, England

On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell. Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

Cheers
--
Clive

On Thursday, 5 January 2017 14:05:39 UTC, The Natural Philosopher wrote:
On 05/01/17 15:26, tabbypurr wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.

More or less utter ********

Hardly. See
https://www.bourns.com/pdfs/OnlinePo...erHandbook.pdf
p17 fig 1.5.

The slide wire resistance was connected across a battery, and a galvanometer connected from its tapping to the voltage under test. Move the connecting point on the zigzag slide wire until the galv nulls out, at which point you have a voltage match. The slide wire is marked 0-100 so you can multiply the %age by the reference battery voltage to get your voltage reading. (You'd also use it on a reference cell before making your measurement to get it set precisely.) This is how voltage was measured before voltmeters came into existence. It's painfully slow but capable of impressive accuracy.

A zigzag shape wire was used to get as much length as practical on a given space of board, and today's zigzag R symbol comes from that. Much later test sets put the wire into a spiral to save more space.


NT

wrote:
A zigzag shape wire was used to get as much length as practical on a given
space of board, and today's zigzag R symbol comes from that. Much later
test sets put the wire into a spiral to save more space.

The zigzag symbol is no longer the standard though is it? A boring
rectangular box is used nowadays.

--
Chris Green
·

On 05/01/17 16:26, charles wrote:
all resistors, fixed and variable use a zigzag symbol.

No, the IEC standard is an oblong box these days

https://en.wikipedia.org/wiki/Electr...ds_for_symbols

On 05/01/17 16:29, Clive Arthur wrote:
On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell.

No, it wasnt that nor was it used that way. It is to 'meter' potential -
i.e. reduce it proportionat;y.

NOTHING to do with measuring at all.


Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

NO, they never ever were.

Because yo cant slide anyhing up a zigzag.
They were originally wound wire on e.g. ceramic formers with sliding
contacts.

zigzags are just easy to draw. But boxes are easier, and boxes have been
IEC standard ever since I've been in electronics in the late 60s.

Cheers

On 05/01/17 16:30, wrote:
On Thursday, 5 January 2017 14:05:39 UTC, The Natural Philosopher wrote:
On 05/01/17 15:26, tabbypurr wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.

More or less utter ********

Hardly. See
https://www.bourns.com/pdfs/OnlinePo...erHandbook.pdf
p17 fig 1.5.


That isn't why its called a potentiometer though.

That's just a standard half bridge.

The slide wire resistance was connected across a battery, and a galvanometer connected from its tapping to the voltage under test. Move the connecting point on the zigzag slide wire until the galv nulls out, at which point you have a voltage match. The slide wire is marked 0-100 so you can multiply the %age by the reference battery voltage to get your voltage reading. (You'd also use it on a reference cell before making your measurement to get it set precisely.) This is how voltage was measured before voltmeters came into existence. It's painfully slow but capable of impressive accuracy.

A zigzag shape wire was used to get as much length as practical on a given space of board, and today's zigzag R symbol comes from that. Much later test sets put the wire into a spiral to save more space.


NT

On 05/01/17 16:29, Clive Arthur wrote:
On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell. Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

Cheers

voltage divider

Word Origin

noun, Electricity.
1.
a resistor or series of resistors connected to a voltage source and used
to provide voltages that are fractions of that of the source.
Also called potential divider, *potentiometer*.

On Thu, 5 Jan 2017 16:05:37 +0200, The Natural Philosopher wrote:

On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.


NT

More or less utter ********

More or less true, actually.

I'm sure you understand how adding the word "actually" considerably enhances the trueness
of a statement.



--
Regards, Paul Herber
http://www.paulherber.co.uk/

On Thursday, 5 January 2017 16:01:11 UTC, Paul Herber wrote:
On Thu, 5 Jan 2017 16:05:37 +0200, The Natural Philosopher wrote:

On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.


NT

More or less utter ********

More or less true, actually.

They were never zig-zaged wire the were wound, today you can still buy wirewound resistors.
What some might be getting confused with is the wheathstone bridge which was used to measure potentail or voltage, this may have used a zig zag to a more precise measurement could be taken.

Next you'll be saying that transformers use curly wire in them.
Or wire that looks like a series of Us

In article ,
Chris Green wrote:
wrote:
A zigzag shape wire was used to get as much length as practical on a
given space of board, and today's zigzag R symbol comes from that.
Much later test sets put the wire into a spiral to save more space.

The zigzag symbol is no longer the standard though is it? A boring
rectangular box is used nowadays.

Allows you to put the value or number inside rather than underneath, etc.

PITA when all components etc become just a box like I've seen in some car
schematics.

--
*If work is so terrific, how come they have to pay you to do it?

Dave Plowman London SW
To e-mail, change noise into sound.

twaddle snipped

Dig all you like, I can't be arsed to bother with such dogmatic
ignorance. I gather you make a habit of it. Out.

Cheers
--
Clive

On 05/01/2017 16:12, whisky-dave wrote:

snip

They were never zig-zaged wire the were wound,

http://bestoinstruments.com/product/...il-Jockey.aspx

http://www.kpagenciesambala.com/physics43.html

http://www.indiamart.com/salooja-bro...quipments.html

https://www.youtube.com/watch?v=C76yxIgbqac

https://www.youtube.com/watch?v=H8PI2yRguh8

Cheers
--
Clive

On 05/01/17 18:50, Clive Arthur wrote:
On 05/01/2017 16:12, whisky-dave wrote:

snip

They were never zig-zaged wire the were wound,

http://bestoinstruments.com/product/...il-Jockey.aspx


http://www.kpagenciesambala.com/physics43.html

http://www.indiamart.com/salooja-bro...quipments.html

https://www.youtube.com/watch?v=C76yxIgbqac

https://www.youtube.com/watch?v=H8PI2yRguh8

Cheers
Those indians must have seen the zigzag symbol and thought that is how
you make a variable resistor!

Bless!

On Thursday, 5 January 2017 15:03:04 UTC, Chris Green wrote:
tabbypurr wrote:
A zigzag shape wire was used to get as much length as practical on a given
space of board, and today's zigzag R symbol comes from that. Much later
test sets put the wire into a spiral to save more space.

The zigzag symbol is no longer the standard though is it? A boring
rectangular box is used nowadays.

It's one of the standards. I try not to get too sucked into the fashion side of standards.


NT

On 05/01/17 18:01, Paul Herber wrote:
On Thu, 5 Jan 2017 16:05:37 +0200, The Natural Philosopher wrote:

On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe they can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure voltages. And their zigzag symbol apes their original physical construction, a long zigzag of wire on a board.


NT

More or less utter ********

More or less true, actually.

I'm sure you understand how adding the word "actually" considerably enhances the trueness
of a statement.

Not really no. Usually it means that its ********, and someone is trying
to make it sound less ********.

On 05/01/17 19:09, wrote:
On Thursday, 5 January 2017 15:03:04 UTC, Chris Green wrote:
tabbypurr wrote:
A zigzag shape wire was used to get as much length as practical on a given
space of board, and today's zigzag R symbol comes from that. Much later
test sets put the wire into a spiral to save more space.

The zigzag symbol is no longer the standard though is it? A boring
rectangular box is used nowadays.

It's one of the standards. I try not to get too sucked into the fashion side of standards.


Only USA uses it now I think.

NT

On Thursday, 5 January 2017 15:50:16 UTC, The Natural Philosopher wrote:
On 05/01/17 16:29, Clive Arthur wrote:
On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, tabbypurr wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell.

No, it wasnt that nor was it used that way. It is to 'meter' potential -
i.e. reduce it proportionat;y.

NOTHING to do with measuring at all.

Do galvanometers also meter out galvs? Seriously, voltage measuring is what they were used for.

Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

NO, they never ever were.

Because yo cant slide anyhing up a zigzag.

I've seen old ones in zigzag form. The modern version is parallel wires. There is nothing in any way difficult about sliding a contact along a wire pegged to a board in a zigzag. It's trivial.

They were originally wound wire on e.g. ceramic formers with sliding
contacts.

that's been done too. Early ones were simpler than that.

zigzags are just easy to draw. But boxes are easier, and boxes have been
IEC standard ever since I've been in electronics in the late 60s.

which so many mfrs don't altogether follow, but that's another story.


NT

On Thursday, 5 January 2017 16:12:29 UTC, whisky-dave wrote:

Next you'll be saying that transformers use curly wire in them.
Or wire that looks like a series of Us

Ah, it's Mr. Makeitup.


NT

In article ,
The Natural Philosopher wrote:
On 05/01/17 16:26, charles wrote:
all resistors, fixed and variable use a zigzag symbol.

No, the IEC standard is an oblong box these days

https://en.wikipedia.org/wiki/Electr...ds_for_symbols


I know - I meant to say "used". But my Mullard "Transistor Circuits for
the Experimenter" uses zig-zags!

--
from KT24 in Surrey, England

In article ,
The Natural Philosopher wrote:
On 05/01/17 16:29, Clive Arthur wrote:
On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell.

No, it wasnt that nor was it used that way. It is to 'meter' potential -
i.e. reduce it proportionat;y.

NOTHING to do with measuring at all.


Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

NO, they never ever were.

Because yo cant slide anyhing up a zigzag.
They were originally wound wire on e.g. ceramic formers with sliding
contacts.

zigzags are just easy to draw. But boxes are easier, and boxes have been
IEC standard ever since I've been in electronics in the late 60s.

Cheers

Checks Bookshelf: 1969 publication still using zig-zags.

--
from KT24 in Surrey, England

On Thursday, 5 January 2017 17:12:25 UTC, The Natural Philosopher wrote:
On 05/01/17 19:09, tabbypurr wrote:
On Thursday, 5 January 2017 15:03:04 UTC, Chris Green wrote:
tabbypurr wrote:

A zigzag shape wire was used to get as much length as practical on a given
space of board, and today's zigzag R symbol comes from that. Much later
test sets put the wire into a spiral to save more space.

The zigzag symbol is no longer the standard though is it? A boring
rectangular box is used nowadays.

It's one of the standards. I try not to get too sucked into the fashion side of standards.


Only USA uses it now I think.

USA, Japan, and various other people. Its one of the main standards.


NT

On Thursday, 5 January 2017 17:09:11 UTC, The Natural Philosopher wrote:
On 05/01/17 18:50, Clive Arthur wrote:
On 05/01/2017 16:12, whisky-dave wrote:

snip

They were never zig-zaged wire the were wound,

http://bestoinstruments.com/product/...il-Jockey.aspx


http://www.kpagenciesambala.com/physics43.html

http://www.indiamart.com/salooja-bro...quipments.html

https://www.youtube.com/watch?v=C76yxIgbqac

https://www.youtube.com/watch?v=H8PI2yRguh8

Cheers
Those indians must have seen the zigzag symbol and thought that is how
you make a variable resistor!

Bless!

If you'd googled you'd have noticed those are used around the world for education & to a lesser extent calibration.

But I'm ceasing to care, it's not like you have much sensible to say about it.


NT

On 05/01/17 19:29, charles wrote:
In article ,
The Natural Philosopher wrote:
On 05/01/17 16:29, Clive Arthur wrote:
On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell.

No, it wasnt that nor was it used that way. It is to 'meter' potential -
i.e. reduce it proportionat;y.

NOTHING to do with measuring at all.


Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

NO, they never ever were.

Because yo cant slide anyhing up a zigzag.
They were originally wound wire on e.g. ceramic formers with sliding
contacts.

zigzags are just easy to draw. But boxes are easier, and boxes have been
IEC standard ever since I've been in electronics in the late 60s.

Cheers

Checks Bookshelf: 1969 publication still using zig-zags.

that was when it all changed. I moved to Marconi's in 1969, and the
standard was boxes. Woe betide you if you drew zigzags.

On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

Why?

Which bit of it?

On 05/01/2017 15:50, The Natural Philosopher wrote:
On 05/01/17 16:29, Clive Arthur wrote:
On 05/01/2017 14:05, The Natural Philosopher wrote:
On 05/01/17 15:26, wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.


NT

More or less utter ********

No, that's quite right. A potentiometer was originally used to measure
potential, or voltage, and would include what we now call a
potentiometer with a galvanometer and a reference cell.

No, it wasnt that nor was it used that way. It is to 'meter' potential -
i.e. reduce it proportionat;y.

NOTHING to do with measuring at all.


Later, the term
became applied to the resistive part alone. They were often made with
resistance wire zig-zagging up and down a wooden board in order to make
sufficient length.

NO, they never ever were.

Because yo cant slide anyhing up a zigzag.
They were originally wound wire on e.g. ceramic formers with sliding
contacts.

zigzags are just easy to draw. But boxes are easier, and boxes have been
IEC standard ever since I've been in electronics in the late 60s.

Cheers

Now who's talking ********?

wrote
whisky-dave wrote

I think the reason why they are called potentiomenters is becausxe they
can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure
voltages.

Nope, that is a completely different use of that word.

The variable resistor type of pot can not be used to measure voltages.

And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.

That mangles the story too.

wrote in message
...
On Thursday, 5 January 2017 14:05:39 UTC, The Natural Philosopher wrote:
On 05/01/17 15:26, tabbypurr wrote:
On Thursday, 5 January 2017 11:21:35 UTC, whisky-dave wrote:

I think the reason why they are called potentiomenters is becausxe
they can divide the potential applied to the end terminals using the
'wiper'

They're called potentiometers because they were originally used to
measure voltages. And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.

More or less utter ********

Hardly. See
https://www.bourns.com/pdfs/OnlinePo...erHandbook.pdf
p17 fig 1.5.

The slide wire resistance was connected across a battery, and a
galvanometer connected from its tapping to the voltage under test. Move
the connecting point on the zigzag slide wire until the galv nulls out, at
which point you have a voltage match. The slide wire is marked 0-100 so
you can multiply the %age by the reference battery voltage to get your
voltage reading. (You'd also use it on a reference cell before making your
measurement to get it set precisely.) This is how voltage was measured
before voltmeters came into existence. It's painfully slow but capable of
impressive accuracy.

That was just one use of a variable resistor. Plenty more were used before
that.

A zigzag shape wire was used to get as much length as practical on a given
space of board, and today's zigzag R symbol comes from that. Much later
test sets put the wire into a spiral to save more space.


NT

On Thursday, 5 January 2017 19:28:03 UTC, Rod Speed wrote:
tabbypurr wrote
whisky-dave wrote

I think the reason why they are called potentiomenters is becausxe they
can divide the potential applied to the end terminals using the 'wiper'

They're called potentiometers because they were originally used to measure
voltages.

Nope, that is a completely different use of that word.

The variable resistor type of pot can not be used to measure voltages.

And their zigzag symbol apes their original physical
construction, a long zigzag of wire on a board.

That mangles the story too.

I see you're someone that doesn't even bother to read what's been offered before replying.