Need help figuring this circuit

[indulis]

It more about the calculation itself. True, no one would ever specify a resistor to 10 places, but in the calculation it could make a difference. In this day and age there really is no reason for not being precise… it’s not like the only tool available is a slide rule.

In this case Eric’s solution and a “more precise” answer differ by ~.3. .3 could make a difference…as an example, suppose an equation was given whose solution was in units of KΩ’s, and you were looking at the E-192 series standard values 14.0, 14.2 and 14.3… three standard values which differ by .3. Which one do you choose?

 

[MrAl]

Well my answer has to be correct because when we did the lab, all my values were good.

And before doing it with real resistors, we had calculated 6.35k.

What is LTspice ?

Hello,

With your updated value for R5 equal to 2.2k i get R=6.762852k so i still dont see how anybody got 6.35k.
Did you all use some -tolerance for the resistors?

 

[Roff]

Hello,

With your updated value for R5 equal to 2.2k i get R=6.762852k so i still dont see how anybody got 6.35k.
Did you all use some -tolerance for the resistors?

That's what I get also. I'll bet there is another error in the schematic. Maybe more.

EDIT: If you change R4 to 4.7k, you get 6.34563k for the total resistance, which, of course, rounds up to 6.35k.

 

[Roff]

What is LTspice ?

Google is your friend.

 

[ElectroNewby]

Google is your friend.

If ya too lazy to answer don't reply this thread ?

 

[MrAl]

Hello again,


Not to beat the proverbial dead horse anymore, but could it be possible that you made another mistake with that 47k resistor too? I dont think it is dumb or anything to make these kinds of mistakes we all make them plenty of times. The solution is to simply correct the problem and move on...no problem there. As you do more and more problems like this you get better and better, but there's always going to be human error, and the best human error is the one we make ourselves because figuring out our own mistakes is a lot easier than trying to figure out how to correct someone elses errors.

I've found numerous errors in technical documents on the internet made by professionals and amateurs alike, and spend hours and hours and hours trying to correct them.

 

[InventionUnlimited]

If ya too lazy to answer don't reply this thread ?

Im sorry, and dont mean to offend - but I dont think that is the way to respond to what seems to be a very respected member of this site. Roff has already taken time to explain his calculations, and even suggested bits to check to make the sums add up. The least you could do is help yourself a little.

 

[Roff]

If ya too lazy to answer don't reply this thread ?

Dear ingrate: If ya too lazy to look it up, I think maybe I'll put you on my Ignore List.
It takes you less time to Google "LTspice" than it does for me to explain it, or even look up the URL and link to it.

 

[ElectroNewby]

Ok sorry, did not mean to be rude. I just really don't like the expression 'google is your friend'. I can't keep from seeing it like, "hey you noob! use google, idiot! I'm not gonna tell you! ". But it's probably my imagination.

And yes the 47k was also a mistake. I don't know why I had those, maybe a problem when I entered the values in Multisim... that's embarrasing.

Also btw, Google isn't my friend at all. I hate them now, I use to like Google. Now that they bought YouTube, you have to sync your YouTube account with your Google account and they want to see every move you make and researches. I hate how they want to be so much 'in your face', and life. - My share of opinion.

When I google Ltspice I see a lot a pages saying it's a sim based of Spice 3 and that's exactly the kind of things that I don't like when google-ing, it's never as to-the-point as somebody telling you directly...

But you are right. I'm too lazy to google (and busy with a philo essay atm lol but it's not the right forum to talk about Rene Descartes)

 

[MrAl]

Hi,

Go to the Linear Tech site and look for their "SwitcherCad3" program. That's their simulator, and it is free for download and free for use.
That will allow you to simulate circuits. They also call it LTSpiceIV.

https://www.linear.com/designtools/software/