Negative Resistance Circuit realized with one Op Amp

[@STEMprof]

Thanks for watching. For more Analog & Op Amp Circuit examples please see Converting Capacitor to Inductor th-cam.com/video/weIHG45G6Pg/w-d-xo.html
Logarithm Analog Computer with Op Amp th-cam.com/video/RpKEq5WyoLg/w-d-xo.html
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Analog Computer circuit that solves Differential Equation. And th-cam.com/video/HeZRtnRXpEI/w-d-xo.html
Capacitor to Inductor Converter Circuit th-cam.com/video/weIHG45G6Pg/w-d-xo.html
Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html
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Differential Equation Solver Analog Circuit th-cam.com/video/R3X5AYNZGEI/w-d-xo.html
Diode-Amplifier VTC is analyzed in th-cam.com/video/vpGZkafxMJM/w-d-xo.html
th-cam.com/video/HeZRtnRXpEI/w-d-xo.html presents a circuit with op amps and feedback loops to design an analog computer that solves a second order differential equation.
For more analog signal processing examples see: th-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these Circuit engineering and analysis videos are helpful. 🙋‍♂️

[@assistantgoogle8719]

Hello,
Can you explane how can you arrived to vin expression at 4:51 ?
Vin=(1+R1/R2)*(V+)-(R1/R2)*V0

[@STEMprof]

Thanks for watching. Answering your question, notice that at 4:10 using KCL I show that (Vin-V+)/R1 = (V+-Vo)/R2 . Move V+ from the left side if this equation to the right side and you get the revised equation that you were asking about. For more Op Amp Circuit examples pls see th-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope this is helpful. 🙋‍♂️

[@assistantgoogle8719]

Ok, now I have understand.
(Vin - V+)/R1 = (V+ - V0)/R2 ;
Vin - V+ = (V+ - V0)/R2 * R1 ;
Vin = (V+ - V0)/R2 * R1 + V+ ;
;
(V+ - V0)R1/R2 + V+ ;
(V+)R1/R2 - (V0)R1/R2 + V+ ;
(V+)(1+R1/R2) - (V0)(R1/R2) ;

[@STEMprof]

Glad that the explanation of circuit analysis is helpful. Thanks for watching this circuit video of simulating Negative resistance using one operational amplifier.

[@谢泽文-n4x]

Hello, I have a question about stable circvit: How is R4/R3>R1/R2 derived? Can you answer it for me, thank you.

[@STEMprof]

That's a good question. One quick way to derive R4/R3>R1/R2 is: For stable circuit we need dominant negative feedback in this circuit. That means the contribution of output voltage Vo to the negative input terminal R4/(R3+R4)*Vo should be larger than its contribution to positive input terminal R1/(R1+R2)*Vo. Therefore R4/(R3+R4)>R1/(R1+R2) which results in R4/R3>R1/R2. I hope this circuit video and explanation are helpful.

[@谢泽文-n4x]

@@STEMprof ok, thank you for your answer and wish you good luck.

[@STEMprof]

@@谢泽文-n4x You are welcome, Thank you! Glad that the clarification was helpful.