An interesting question  - Page 1
Forum section: electronics / general

author: Sarvesaa
author_rank: Contributor
timestamp: July 26, 2022, 02:44:28 pm
content: Dear friends,Today I appeared for a competitive exam where I got this question they are asking the total current through circuit. I have attached the circuit down.I think you find it interesting.Thank you

author: TimFox
author_rank: Super Contributor
timestamp: July 26, 2022, 03:20:59 pm
content: Since, by inspection, there is no voltage across the "diagonal" 5 ohm resistor, and therefore no current through it, the solution is straightforward.

author: eugene
author_rank: Frequent Contributor
timestamp: July 26, 2022, 03:30:26 pm
content: Quote from: TimFox on July 26, 2022, 03:20:59 pmWhich I assume is the real reason for the question: to see who does and does not see the symmetry.

author: pqass
author_rank: Super Contributor
timestamp: July 26, 2022, 03:37:13 pm
content: How to solve resistor cube problems:

author: Sarvesaa
author_rank: Contributor
timestamp: July 26, 2022, 04:10:20 pm
content: Yes its straight forward if you know that 3/6 = 3/6 so its simply a balanced wheatstone bridge. Since it is balanced no current flows through the5resistor. The total resistance is6and the total current is1ampere with 6volt battery.Thank youEdit The total current is 0.8333 A with 5volt battery as given in the circuit

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 26, 2022, 04:15:17 pm
content: Quote from: Sarvesaa on July 26, 2022, 04:10:20 pmWith 5V and 6ohm the current is 0.833333333A instead of 1A

author: TimFox
author_rank: Super Contributor
timestamp: July 26, 2022, 04:15:38 pm
content: Mid-way through my career, I learned to be careful to use "straightforward" instead of "trivial" when asked for useful solutions to practical problems.

author: Sarvesaa
author_rank: Contributor
timestamp: July 26, 2022, 04:23:17 pm
content: Dohin the question paper it was 6v and I am still sticked to that. Very sorryYes with a 5v battery it is 0.83333333 AThanks for noting that.

author: niconiconi
author_rank: Frequent Contributor
timestamp: July 27, 2022, 06:14:40 am
content: These kinds of bridge circuits are usually analyzed by using KVL and KCL and writing down the loop equations, but this can be a tedious and cumbersome process. There's an advanced technique called Extra Element Theorem (EET) by R. D. Middlebrook, which allows one to simplify the analysis significantly in some cases.This Theorem basically allows you to replace an unwanted component in a circuit with an open circuit and a short circuit, then the total input impedance can be calculated immediately using the EET formula. For example, it allows you to derive the general formula for the input impedance of a non-balanced Wheatstone bridge with arbitrary resistor values, without solving a single equation.

author: emece67
author_rank: Frequent Contributor
timestamp: July 27, 2022, 09:38:39 am
content: .

author: Sarvesaa
author_rank: Contributor
timestamp: July 27, 2022, 11:48:13 am
content: Since I am a high schooler I found it interesting.

author: armandine2
author_rank: Frequent Contributor
timestamp: July 27, 2022, 12:21:14 pm
content: You might find the following interesting tooand worth some time to consider - it is puzzling to me, but beginning to make some sense.... known in my copy of Tietze and SchenkElectronic Circuitsas a double centre tap full wavebut also Dual Polarity Full-Wave Centre Taphttps://forum.allaboutcircuits.com/threads/dual-polarity-full-wave-center-tap-rectifier.30066/

author: tooki
author_rank: Super Contributor
timestamp: July 27, 2022, 02:04:50 pm
content: Quote from: Sarvesaa on July 26, 2022, 02:44:28 pmI had a similar problem in class recently, and another approach is wye-delta transformation.

author: TimFox
author_rank: Super Contributor
timestamp: July 27, 2022, 03:33:32 pm
content: The wye-delta transformation and the series-parallel impedance transformation are extremely powerful methods for circuit analysis.I always had a list of these transformation equations prominently on the bulletin board next to my desk before retiring.

author: EPAIII
author_rank: Super Contributor
timestamp: July 28, 2022, 06:01:20 am
content: Yes, once you realize that, the problem is a trivial exercise in series and parallel resistor combinations. Then Ohm's law and done.Now, substitute the values of 1, 2, 3, 5, 7, and 11 Ohms for each of the resistors, any order you want, and then solve it. That will separate the men from the boys.Quote from: eugene on July 26, 2022, 03:30:26 pm

author: PlainName
author_rank: Super Contributor
timestamp: July 28, 2022, 09:04:28 pm
content: Quote from: niconiconi on July 27, 2022, 06:14:40 amWhat is is the point of having thumbnails if you're going to hog my screen with the full sized thingas well? The stuff wasn't even interleaved in your text as if if had to go in a specific position.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 28, 2022, 09:16:43 pm
content: Quote from: dunkemhigh on July 28, 2022, 09:04:28 pmAnd now it's quoted to take up double the space and OP can't edit your copy of it. Well done.Tim

author: tooki
author_rank: Super Contributor
timestamp: July 28, 2022, 09:35:01 pm
content: Quote from: dunkemhigh on July 28, 2022, 09:04:28 pmWhile it’s true that there was no pressing need to inline the images, surely you must be aware that there’s no way to attach* an image to a postwithouthaving the thumbnails, regardless of whether they’re later inserted inline or not.*meaning attaching it using the forum’s own hosting, not an external hosting provider.

author: PlainName
author_rank: Super Contributor
timestamp: July 29, 2022, 08:23:44 am
content: Quote from: T3sl4co1l on July 28, 2022, 09:16:43 pmYes, that was an intentional example of stuff we see on EEVBlog. You might recall that I am often taking to task for NOT doing the full-fat quote stuff!

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 29, 2022, 02:25:49 pm
content: Wait, I'm confused here. When I attach an image, am I supposed to leave it as an attachment (which means anyone interested has to click on it), or have the expanded version within the body of the message (so that everyone can immediately see what I'm referring to)? I prefer the latter, but..

author: PlainName
author_rank: Super Contributor
timestamp: July 29, 2022, 02:50:33 pm
content: Are you serious? Really?We chat about stuff on EEVBlog. Sometimes an illustration is useful, perhaps a photo or whatever. But those things take up space and are secondary - we may not be arsed to look, and once seen we probably don't need to keep seeing them. This is not pinterest.com, nor is it tiktok.Photos and stuff don't reflow and take time to download (again!) and make the text of long pages jump around as they get belatedly loaded. The solution is to have thumbnails, which don't get in the way but if one is interested it is really very easy to just click on it and see it in a bigger format.Doesn't someone keep apologising for walls of text? And yet what we have here is a bloody photo of a wall of text, and it's blown up bigger than normal to boot! Well, that's his choice and it would be fine if it were a thumbnail. Oh, bless my soul, there IS a thumbnail but clearly no-one can be trusted to remember to click that every time the page loads, so he has to fill my page with a photo I'm not interested in any more just so I can get to see what someone actually says.QuoteSometimes, and it's rare and only when there are a lot of images with explanatory text, a thumbnail embedded in the body of the post is useful. In this case the things were at the end of the text anyway, just ahead of the bloody thumbnails!But a clever chap like you surely knew all that anyway.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 29, 2022, 03:31:56 pm
content: Quote from: dunkemhigh on July 29, 2022, 02:50:33 pmAnd yet at many times when one writes about a problem with a circuit and does not supply the schematic, the first thing that's asked is "where is the schematic, because it makes it much easier to understand what we are talking (actually writing) about".Or do you have pictures of that, because "they say more than a 1000 words".

author: Nominal Animal
author_rank: Super Contributor
timestamp: July 29, 2022, 03:40:25 pm
content: Quote from: dunkemhigh on July 29, 2022, 02:50:33 pmYes, but not photos of text. I was more thinking of the schematics I've attached to some of my posts in the Beginner forum.Quote from: dunkemhigh on July 29, 2022, 02:50:33 pmYeah, because I know it irritates some members, and even though I'd like to avoid it, I cannot. So it is an acknowledgement that my comms style is lacking.Quote from: dunkemhigh on July 29, 2022, 02:50:33 pmI seriously dislike text-as-pictures, because it renders poorly and tends to look like I had soap in my eyes or something.I honestly didn't know if you (plural, you all) were referring to this particular case, the more general case of funny-but-not-important-to-the-post photos and images, or all images.Quote from: dunkemhigh on July 29, 2022, 02:50:33 pmIt's not cleverness, it is social awareness. Only my directness/honesty about it saves me in real life from the gaffes I occasionally make because my social awareness is a bit limited. Not to any degree of actual diagnosis, but to the degree often encountered in e.g. absent-minded professors and mad scientists.I wouldn't mind being called a mad scientist, really.

author: PlainName
author_rank: Super Contributor
timestamp: July 29, 2022, 04:43:03 pm
content: Quote from: pcprogrammer on July 29, 2022, 03:31:56 pmThat's what the attachment facility withthumbnailsis for.

author: pcprogrammer
author_rank: Super Contributor
timestamp: July 29, 2022, 04:48:24 pm
content: Then you must really hate the TEA thread. That one is full of pictures within the body, and they get quoted a lot

author: SiliconWizard
author_rank: Super Contributor
timestamp: July 29, 2022, 07:44:33 pm
content: Yeah, well, I admit that large inline images can get annoying, and especially when they get quoted."Fortunately", image inlining works so poorly on this forum when creating posts (without having to go through hoops), that I personally don't do it much.