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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

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  • \$\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
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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.

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  • \$\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

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