# Circle with a e around..

#### snowfox

Joined Oct 21, 2007
18
i kno this sounds silly, but in a circuit.. wat does a circle with a e inside represent? wat kind of source is it?

#### Dave

Joined Nov 17, 2003
6,970
I know the guys in the US use E instead of V when referring to voltage. A circle with a V in it is the symbol for a voltmeter, so could this be a different symbol for a voltmeter?

Dave

#### snowfox

Joined Oct 21, 2007
18
In the past we always used a V for a voltage source... but my professor posted this circuit as one of our homeworks...

The section of this problem im trying to do:

Set up a simulation in PSpice to simulate the step response.

So i look at the symbol and was all confused cause i never actually seen it.

I posted a picture of the circuit we had to recreate... maybe it will help if you have a visual.

Yea, I'm from the USA.. we have some wierd conventions so i wouldn't even be surprised if that was the case.

#### Attachments

• 13.2 KB Views: 27

#### Dave

Joined Nov 17, 2003
6,970
That's just a DC voltage source. Indeed the V has been substituted for an E.

Dave

#### snowfox

Joined Oct 21, 2007
18
lol... thanks a bunch dave, i just wanted to clarify these little things.. I don't know why the professor would just throw us a curveball like tat and change his conventions...

#### beenthere

Joined Apr 20, 2004
15,819
Wait until you get some professor bringing in some equipment to fix and you discover that not only do you have to read the manual in German, but the Germans use slightly different symbology as well.

#### Dave

Joined Nov 17, 2003
6,970
lol... thanks a bunch dave, i just wanted to clarify these little things.. I don't know why the professor would just throw us a curveball like tat and change his conventions...
No problems. Good luck with the rest of your assignment.

Wait until you get some professor bringing in some equipment to fix and you discover that not only do you have to read the manual in German, but the Germans use slightly different symbology as well.
Lol! Funny you should say that, I have recently received literature for work we are supposed to be doing for a company in Austria - all in German! I see the occasion diagram I recognise but at the minute I'm not even sure I'm the right guy for the job!

Dave

#### recca02

Joined Apr 2, 2007
1,214
Lol! Funny you should say that, I have recently received literature for work we are supposed to be doing for a company in Austria - all in German! I see the occasion diagram I recognise but at the minute I'm not even sure I'm the right guy for the job!

Dave

you started the elf puzzle.

about the above dia i think there shud not have been a 'e' inside the circle,
and atleast it shud have been a capital 'E'. that was what caused the confusion.
and if its a DC source its much better to draw the ol' symbol for battery.

#### Distort10n

Joined Dec 25, 2006
429
I know the guys in the US use E instead of V when referring to voltage.
Really? I was taught to use V as the symbol for voltage. E I always presumed was electromotive force, which is the same as voltage. Is there any place where one MUST be used instead of the other?

#### recca02

Joined Apr 2, 2007
1,214
I was taught,
E = EMF-sometimes back EMF
V= terminal voltage,
but apart from transformers and motors havent used it both at the same time.

#### Dave

Joined Nov 17, 2003
6,970

you started the elf puzzle.
Lol! Is that what they call karma?!

Really? I was taught to use V as the symbol for voltage. E I always presumed was electromotive force, which is the same as voltage. Is there any place where one MUST be used instead of the other?
In the UK, we very rarely use E at all. For example when Ohm's Law or power equations are quoted we always use V, whereas other sources (of which the e-book on this site is an example), they use E ref. http://www.allaboutcircuits.com/vol_5/chpt_1/1.html

There is a small discussion on this in the Ohm's Law section in Volume I:

The mathematical symbol for each quantity is meaningful as well. The "R" for resistance and the "V" for voltage are both self-explanatory, whereas "I" for current seems a bit weird. The "I" is thought to have been meant to represent "Intensity" (of electron flow), and the other symbol for voltage, "E," stands for "Electromotive force." From what research I've been able to do, there seems to be some dispute over the meaning of "I." The symbols "E" and "V" are interchangeable for the most part, although some texts reserve "E" to represent voltage across a source (such as a battery or generator) and "V" to represent voltage across anything else.