It is here, and it is for College or Homework Projects.
View attachment 289731

Can you share me the link? Thank you

 

Does anyone know any engineer that can help troubleshoot the initial checking will be done on March 17 morning. We are willing to pay. If possible, in person, if not, it's still ok.

 

Hi
Can you share me the link? Thank you

What link? You are already posting to the Homework Help forum with your posts.?

Mod

 

So what is the right solution for this?

1) Use a modern instrumentation amplifier and opamps ICs and a modern circuit for it.
2) Power it with two little CR2032 3V coin batteries.

 

here is an example of virtual ground circuit.
it is just a pair of resistors and capacitors.

one side connects to large supply.
the other side is 3-terminal substitute for split power supply

View attachment 289727

what is that next to the resistors?
I did like that but when I connect to the Vcc and Vee, for example I adjust voltage of the power supply is 10V. When I connect to Vcc, it stops to around 1.8V while Vee is 8.2V. Can you fix this for me?

 

here is an example of virtual ground circuit.
it is just a pair of resistors and capacitors.

one side connects to large supply.
the other side is 3-terminal substitute for split power supply

View attachment 289727

Can I connect the virtual GND to the GND in my circuit? Or I have to separate those GND?

 

Can I connect the virtual GND to the GND in my circuit? Or I have to separate those GND?

Your circuit ground MUST only connect to the virtual ground. Relatively, your 30V power supply negative side is -15V and the positive side of your power supply is +15V.

 

Since your "virtual ground" resistors do not produce identical Vcc and Vss then they work poorly. Use two new 9V batteries instead.

 

Your circuit ground MUST only connect to the virtual ground. Relatively, your 30V power supply negative side is -15V and the positive side of your power supply is +15V.

If you can, draw the diagram for me pls
I did attach the pdf file on the thread

 

 

View attachment 289761

So can I connect that GND to the GND in the circuit?

 

If you can, draw the diagram for me pls
I did attach the pdf file on the thread

I did this, but when I connect the virtual GND to the circuit GND, the voltage of negative and positive are different instead of 15V and -15V

 

Looking at your breadboard I don't see any power supply decoupling capacitors. Adding capacitors in accordance with the datasheet recommendations is a good practice and may save you a lot of time and trouble tracking down performance problems.

 

Looking at your breadboard I don't see any power supply decoupling capacitors. Adding capacitors in accordance with the datasheet recommendations is a good practice and may save you a lot of time and trouble tracking down performance problems.

you mean the bypass capacitor?

 

Most old opamps work perfectly when powered from two NEW 9V batteries instead of +15V and -15V. You measured different battery voltages then maybe one battery is old and needs to be replaced?