- #1

- 87

- 0

I got R_L(max) = 0.0022 [ohm] and R_L(min) = 0.3 [ohm] but I have a feeling that they're not correct. Someone please check.

R_L(max) = |(5 - 2.4)/(3*(-400) + 40))|

R_L(min) = (5 - 0.4)/(16 - (-1.6))

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter aruwin
- Start date

- #1

- 87

- 0

I got R_L(max) = 0.0022 [ohm] and R_L(min) = 0.3 [ohm] but I have a feeling that they're not correct. Someone please check.

R_L(max) = |(5 - 2.4)/(3*(-400) + 40))|

R_L(min) = (5 - 0.4)/(16 - (-1.6))

- #2

mfb

Mentor

- 35,814

- 12,541

R_L(max) looks fine.

- #3

- 87

- 0

R_L(max) looks fine.

Actually this is the actual question. It's about finding the external load resistance of an open collector of standard TTL.

Here's the picture so you can everything clearly. So can you check if I am doing it right?

- #4

mfb

Mentor

- 35,814

- 12,541

You cannot answer this based on your equations.Actually this is the actual question.

Significant figures can be a handy tool to estimate the uncertainty of a result. If you need a proper analysis, use actual uncertainties and not significant figures.

- #5

- 87

- 0

You cannot answer this based on your equations.

Significant figures can be a handy tool to estimate the uncertainty of a result. If you need a proper analysis, use actual uncertainties and not significant figures.

But that's the formula given to find the max/min resistance. So how am I supposed to calculate them?

- #6

mfb

Mentor

- 35,814

- 12,541

- #7

- 87

- 0

Did I get the significant figure right?

I know that when we take account of the significant figures, 5-2.4 would be 3 because there is no decimal value after five so it becomes unknown and we can't just make it 0 and minus 4. But I am not sure about this calculation though, because I don't know if I have to calculate everything normally first and then think about the s.g. when I get the final answer OR taking in account of the s.g. for every step of the calculation. I hope I am clear with my doubts here.

- #8

mfb

Mentor

- 35,814

- 12,541

The second method is better, the first can lead to problems in some types of calculations.But I am not sure about this calculation though, because I don't know if I have to calculate everything normally first and then think about the s.g. when I get the final answer OR taking in account of the s.g. for every step of the calculation.

- #9

- #10

mfb

Mentor

- 35,814

- 12,541

If that value 5 is known to one significant figure only, yes.

- #11

- #12

mfb

Mentor

- 35,814

- 12,541

- #13

- #14

mfb

Mentor

- 35,814

- 12,541

As I said before, yes.

Share: