How would I calculate voltage from a circuit with 2 power supplies,

use KCL

>>1120561
>KCL
Whats that?

Kerchoff's Current Law.

I have no idea how to use that

>>1120573
do what your instructor said to do you lazy fuck

>>1120573
then use KVL

Pirate Multisim if you want to play around with circuits.

>>1120578
Spice is free

>>1120559
I'd do it by paying attention during classes, reading the books I've been assigned and then asking the TA if I still had problems.

>>1120575
>do what your instructor said to do you lazy fuck
He'll probably have to be able to explain how he arrived at his answer too.

>>1120559
from what i remember...
V=IR
I=V\R

so...for the 5v:
I = 5\68
I = 73.6 milliamps
----------
I = 3.8\30
I = 127 milliamps

>>1120634
Nope.
You need Kirchhoff's laws for this.
If only the left half existed, the top of R2 would be 2.5333 volts, and if only the right half existed, the top of R2 would be 1.47 volts.
So Ohm's law is out the window.
I can't remember the rest, but Kirchhoff's two laws should solve it.

the reason nobody knows this by heart is coz it has zero relation to actual electronics problems. you'll never need this shit in real life.

Use superposition to find the voltage on both sides. Also, buy Every circuit simulator. Checks work.

File: 1485253113857.png (15KB, 476x222px) Image search: [Google]

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(I1+I2)*R2+I1*R1=3,8V
(I1+I2)*R2+I2*R3=5V

two equations, two unknowns

>>1120559
mesh current or node voltage methods
from there ether KVL or KCL respectivly
also read your book, if you cant recognize that simply, you're going to have a tough time later on

>>1120645
>ye olde no one needs algebra meme, redux

>>1120559
Convert each voltage source, resistor pair on the sides of this circuit to their Norton equivalent circuit. Solve for the voltage across R2 and work backwards to get the current contribution from each voltage source.

Use the Super Position principle. Draw two diagrams, one with one of the voltage sources replaced with a short (open for current sources). Calculate the current through the resistor network, it should be easy now since its just series/parallel resistance calculations with that short thrown in. Now make sure you have the current directions reasoned out on each of your diagrams, and just add each respective current for each node from both diagrams together, being sure to mind the current directions, opposing directions subtract. This is really intuitive since the ideal impedance of a voltage source is 0, and current source is infinite.

>>1120884

more like, no one in history has ever needed to calculate the area of a rhombus, except HS students who were forced to learn the formula.

>>1120645
>the reason nobody knows this by heart

And yet there is some pretty decent advice in this thread.

>>1121747
Not surprising, considering how much time colleges spend on running spice on pen and paper.

>>1121670
Saying you never needed it just shows that you do not know it and thus never consider it an option.

>>1121749
Getting answers from google/spice/wolfram without having the faintest idea on how a problem is actually solved seems to be a trend with this generation.
Look mom! No brain!

>>1121797
There are plenty of things which are good to know, but which have relatively little practical value.

>>1121802
True. But if you don't know them, then you don't realize when you could use them either.

Kind of like words. You very rarely need the fancy words if you don't know them, but once you do they are the only ones that really fit what you want to say.

>>1121749
>how much time colleges spend on running spice on pen and paper.

Difference between being a technician and engineer: Engineers need to understand the first principles behind the problem. Many techs are happy to run Spice and get an answer. And then they bitch when Spice won't converge, with no idea how the models work.

>>1121849
>they are the only ones that really fit what you want to say.

Indubitably.

>>1121670
>no one in history has ever needed to calculate the area of a rhombus
Aside from people like architects, engineers, surveyors, etc..

>>1121911

my nephew is an architect. i emailed him at work to ask if he knew how to calculate the are of a rhombus without googling it. he did not, and neither did 3 other partners he asked at lunch. that's 4 architects with some 60 years of combined experience.

>>1121884
It is one thing to know how, say, node-voltage analysis works and another thing spend week after week running it on pen and paper. Doubly so, when the practice revolves around highly artificial circuits, chosen so that symbolic math still works with them.
I can't help but think that the emphasis on that stuff was just a relic from the past.

>And then they bitch when Spice won't converge
I don't know about your school, but mine didn't really spend much time on studying the inner workings of Spice and the problems associated with its algorithms.

>>1121933
Wow he sounds pretty fucking stupid. It's just a fucked up square how can't you work that out Jesus fuck what a dumb asshole. Take the triangle from one end and put it on the other end, it's absolutely trivial.

>>1120647
Doing it using superposition is the easiest

>>1121933
I suppose there are good and bad architects in the world. The chance you'll need it and not know is enough to say they're not at their best.

>>1121933
architects are notorious for being fucking stupid

>>1121933
60 years of combined idiocy

>>1120645
>knowing by heart
it's called understanding the problem and knowing how to apply the math to solve the problem

>>1120790
it is this fucking simple

good luck building any kind of circuit without intuitively understanding this

>>1120559
I got currents of about 96.6 mA from the 3.8 V source and about 45.1 mA from the 5 V source using equivalent transformation like >>1120934 suggested. Step by step on request.

http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+10.20027730826997+50+5+50%0Av+64+304+64+256+0+0+40+3.8+0+0+0.5%0Av+592+304+592+256+0+0+40+5+0+0+0.5%0Ar+272+144+272+224+0+1%0Ar+336+224+336+304+0+20%0Ar+400+144+400+224+0+48%0A370+160+64+160+144+1+0%0A370+512+64+512+144+1+0%0Aw+160+144+272+144+0%0Aw+400+144+512+144+0%0Aw+272+224+400+224+0%0Aw+592+256+592+64+0%0Aw+592+304+336+304+0%0Aw+336+304+64+304+0%0Aw+64+256+64+64+0%0Aw+64+64+160+64+0%0Aw+512+64+592+64+0%0Ap+464+224+464+144+1+0%0Ap+272+224+272+304+1+0%0Ap+400+144+272+144+1+0%0Ap+208+224+208+144+1+0%0Aw+208+224+272+224+0%0Aw+464+224+400+224+0%0A

>>1122504
R1 has wrong value

File: circuit.png (10KB, 600x300px) Image search: [Google]

10KB, 600x300px

>>1122513
Double-click the component to edit the value

>>1122515
R2 20Ω has a bad connection (red dot), carries no current. What do?

>>1122526
Split the wire between R1, R2 and R3

http://www.falstad.com/circuit/circuitjs.html?cct=$+1+0.000005+10.20027730826997+50+5+50%0Av+64+304+64+256+0+0+40+3.8+0+0+0.5%0Av+592+304+592+256+0+0+40+5+0+0+0.5%0Ar+272+144+272+224+0+10%0Ar+336+224+336+304+0+20%0Ar+400+144+400+224+0+48%0A370+160+64+160+144+1+0%0A370+512+64+512+144+1+0%0Aw+160+144+272+144+0%0Aw+400+144+512+144+0%0Aw+272+224+336+224+0%0Aw+592+256+592+64+0%0Aw+592+304+336+304+0%0Aw+336+304+64+304+0%0Aw+64+256+64+64+0%0Aw+64+64+160+64+0%0Aw+512+64+592+64+0%0Ap+464+224+464+144+1+0%0Ap+272+224+272+304+1+0%0Ap+400+144+272+144+1+0%0Ap+208+224+208+144+1+0%0Aw+208+224+272+224+0%0Aw+464+224+400+224+0%0Aw+336+224+400+224+0%0A

File: circuit.png (10KB, 633x299px) Image search: [Google]

10KB, 633x299px

>>1122531
Thanks, works.

>>1122549
Not trying to say you're retarded, but if you need such a tool to solve this you're pretty retarded

>>1122702
Why so hostile? Bad hair day? It's the first time I touched a simulator, just for fun and giggles. At least it finally produced the results I already posted at >>1122497.

>>1122715
just saying how it is

>>1122718

good for you for standing up for your principles: shitting on other people to make yourself feel good has always been a necessary component of DIY discussions. the world needs more assholes like you.

>>1122784
If someone needs Maple or Matlab to calculate 2+3 i won't hesitate to call him a dumbass
This isn't your safe space senpai

>>1122784
We don't shit on others to make ourselves feel better. We shit on others so they'd stop shitting up the whole place.

>>1120623

But if everyone controls the Spice, who controls the universe?

>>1122526
>R2 20Ω has a bad connection

Bad solder joint, no doubt.

>>1122814
>Maple or Matlab to calculate 2+3

its fucking falstad.
a browser based sim.

>>1124566
>Wolfram alpha to calculate 2+3

Not OP but thanks for the replies
This was an interesting problem

>>1121749
>Running spice on pen and paper
>2017
Anything less than a corellian freighter is pleb tier

>>1120561
Got an EE degree and detested all the work involved for those methods. Asked every professor in the college to give me something better that works in all situations.

Have you heard of node voltage method? It's combines kcl and kvl so you need node - 1 equations to get a full power diagram.

>>1125442
You had to ask your profs for node voltage and mesh current? I was taught that stuff in Circuits 1. That stuff should be in any decent circuits textbook.