1) If you pull up on the (+) input the output goes up.
2) If you pull up on the (-) input the output goes down.

The input signal has 0.05V offset. It is moved up by 0.05V and we want to remove that. There are many ways to do this but one is to use comment 2) above. Connect a very large value resistor from (-) to+5V.
Think about a voltage divider made of R3 and R1. Top is +5V supply and center point is (-) input of amp.
R3 is new.
What value of R3 will give you 0.05V?
View attachment 219279
I must go away for 1 hour good luck.

Should we reduce the voltage of the resistor by 0.05v

 

Do you know how to make a voltage divider?

 

Not Really .

 

hi adi,
Look here, AAC
https://www.allaboutcircuits.com/textbook/direct-current/chpt-6/voltage-divider-circuits/
and here
https://www.allaboutcircuits.com/tools/voltage-divider-calculator/

E

 

hi adi,
Look here, AAC
https://www.allaboutcircuits.com/textbook/direct-current/chpt-6/voltage-divider-circuits/
and here
https://www.allaboutcircuits.com/tools/voltage-divider-calculator/

E

Good Morning everyone. I hope you are well. So here i go ready for my lesson for today.

 

so if Vin is 5v and R is 10K i need to find out R3? what is Vout please?

 

so i used the equation Vout= Vin(R1/R1+R1) = 5(10/20)=2.5 V

 

R3=20k if i apply Vout=Vin(1+R1/R3)

 

hi adi,
What value to get for R3 for the question Ron asked you in post #80.?
E

 

Hi, I used the formula you sent me and i got value for R3=20K.

 

1) If you pull up on the (+) input the output goes up.
2) If you pull up on the (-) input the output goes down.

The input signal has 0.05V offset. It is moved up by 0.05V and we want to remove that. There are many ways to do this but one is to use comment 2) above. Connect a very large value resistor from (-) to+5V.
Think about a voltage divider made of R3 and R1. Top is +5V supply and center point is (-) input of amp.
R3 is new.
What value of R3 will give you 0.05V?
View attachment 219279
I must go away for 1 hour good luck.

100k?

 

hi adi,
Sorry No.

Vout required = 0.25V

Vsupply = 5V

Bottom resistor R1 = 10k

Find value of Top resistor R3.

With your answer of 20K, you would get 1.666' Volts

Try again.

E

 

hi,
Using a 100k as post #91 would give 0.454V.

Lets go thru it step by step.


Vout = Vin (R1/(R1+R3))

Transpose the formula for R3= ,,, can you do that.?

E

 

I tried many values but the closest i get is 1k.

 

hi,
Using a 100k as post #91 would give 0.454V.

Lets go thru it step by step.


Vout = Vin (R1/(R1+R3))

Transpose the formula for R3= ,,, can you do that.?

E

Yes i can do that. Thanks

 

hi,
Using a 100k as post #91 would give 0.454V.

Lets go thru it step by step.


Vout = Vin (R1/(R1+R3))

Transpose the formula for R3= ,,, can you do that.?

E

R3=190K?

 

hi adi,
Yes,
but please post your calculations.
E


Now do it for Ron's 0.05V as requested in post #80.... use the same method as for post #93,,, post your answer.

 

0.25=5(10/10+R3), R3=190K

 

hi,
Now do it for Ron's 0.05V as requested in post #80.... use the same method as for post #93,,, post your answer.

E

 

0.5 Vin?