Question

Please Help Me!
a) Find the voltage at point A.
b) How long it takes to voltage at point B to reach 6V?

Answer 1

Please show steps!
I found the solution to a), but b) i have no idea...

Answer 2

i think voltage at A is 6V
is it a monostable multivibrator?

Answer 3

Yes, i found 6V at A too. But for point B i can't find it...
It was not specified if it is monostable multivibrator, but i think we can consider this

Answer 4

Isn't the voltage at point B just going to be the result of hooking the capacitor to +12V through that resistor? Isn't that just a simple RC circuit charging up?

Answer 5

@radar wanted to send a you a private message, but you don't accept them from anyone, apparently

Answer 6

My settings is set to allow anyone to message me...
i though it could be a simple RC circuit, but check this out...

Answer 7

@radar please help

Answer 8

why the voltage cuve is constant? the capacitor is not charging?

Answer 9

@Paulodomingos Why you didn't consider the other 2 10k resistors?

Answer 10

No need to do so — they don't influence the voltage at point B.

Looking at your earlier transient response, I bet if you went and looked at a shorter time range, like from 0-100 ms, you would see the capacitor charging.

Answer 11

I got it! ;) But i tried the transient analysis again in range 0-100ms and i got the same constant voltage line... maybe a bug on the simulator?

Answer 12

You need set 0V at initial condition of the capacitor, to simulate this circuit on eletric simulator.

Answer 13

Ah, yes, need to temporarily close that switch which you didn't simulate :-)

Answer 14

There are some corrections in answer b)

Answer 15

No, I think you had it right the first time. \[C = 1.0 \mu\text{F} = 1.0*10^{-6}\text{ F}\]\[RC = 100 \text{k}\Omega *1.0*10^{-6}\text{ F}= 100*10^3\Omega*1.0*10^{-6}\text{ F} = 10^{-1}\text{ s}\]

Answer 16

Is the dot in 1.000uF a decimal separator? In positive case, excuse me, I'm from Brazil, and we use comma as decimal separator. We use dot as thousand separator.

Answer 17

oh, that's an excellent point! However, this was a problem from a course given in the US, where the . is the decimal separator. Looking at datasheets from companies located in countries where the "," is used as a decimal separator, it appears to me that the standard is to use the "." as the decimal separator for describing electronic devices, regardless of the location practice for numbers.

Answer 18

it is 6v taking the circuit between the 12v source and the ground. then it is just kvl