According to calculations, this circuit should have solved the differential equation 25y''+ 5y' + y= (15,5)x

So when I give x= 0,1 V, y should be 1,55.But it becomes -10V. Why?

For the ltspice file

enter image description here

  • \$\begingroup\$ Circuits don't solve equations. Circuit behavior can be described by an equation. There's an error in the circuit, the output of U3 is shorted to the +10V supply rail. \$\endgroup\$ – Bimpelrekkie Dec 8 '17 at 7:55
  • \$\begingroup\$ @Bimpelrekkie dummies.com/education/science/science-electronics/… \$\endgroup\$ – pipe Dec 8 '17 at 7:57
  • \$\begingroup\$ @pipe OK, I see, sort of like an analog computer. \$\endgroup\$ – Bimpelrekkie Dec 8 '17 at 8:03

It seems like U3's output is connected to the 10 V rail. You probably wanted its positive supply connected since it's left unconnected.

| improve this answer | |
  • \$\begingroup\$ Yes. It now gives correct answer. \$\endgroup\$ – user175079 Dec 8 '17 at 8:06
  • \$\begingroup\$ The final value may be 1.55, but the transient should be a decaying oscillation with \$\zeta=0.5\$ \$\endgroup\$ – Chu Dec 8 '17 at 13:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.