Comments on: Apply Thevenin’s Theorem to Solve a Negative Resistance Circuit, or Current Source https://masteringelectronicsdesign.com/apply-thevenins-theorem-to-solve-a-negative-resistance-circuit/ Electronics Design and Modeling with Emphasis on Analog Design Mon, 14 Nov 2011 15:45:45 +0000 hourly 1 By: Wayne https://masteringelectronicsdesign.com/apply-thevenins-theorem-to-solve-a-negative-resistance-circuit/#comment-3536 Wed, 11 May 2011 06:19:35 +0000 http://MasteringElectronicsDesign.com/?p=1773#comment-3536 I must have stared at EQ. 2 for 15 minutes trying to understand why it was (Vo-Vin)/(R2+R1) rather than (Vo-Vth)/R2. I calculated Vth to be the same when using Superposition which was my default method of choice. It’s all clear now.

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/apply-thevenins-theorem-to-solve-a-negative-resistance-circuit/#comment-3474 Sat, 30 Apr 2011 19:12:57 +0000 http://MasteringElectronicsDesign.com/?p=1773#comment-3474 In reply to Cathy Kowalski.

Thank you, Cathy, for the idea. I will consider it.

]]> By: Cathy Kowalski https://masteringelectronicsdesign.com/apply-thevenins-theorem-to-solve-a-negative-resistance-circuit/#comment-3460 Fri, 29 Apr 2011 21:06:56 +0000 http://MasteringElectronicsDesign.com/?p=1773#comment-3460 great explanation. Would you ever consider publishing an Amazon Kindle Edition of any of your books?

A person can have up to 3500 books on a Kindle and it only weighs 8 ounces.

Sincerely, Cathy

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/apply-thevenins-theorem-to-solve-a-negative-resistance-circuit/#comment-3313 Wed, 30 Mar 2011 06:09:05 +0000 http://MasteringElectronicsDesign.com/?p=1773#comment-3313 In reply to Amp.

VTH comes from the loop equation for VTH, R1 and Vin. Since there is no current in the Op Amp terminals, the voltage drop on R1 is the current through R2 times R1.

“The ckt will reduce to Vin with R1 in series and Vo with R2 in series.”
Correct. In the first stage of the calculation, when we eliminate RL, R1 and R2 have the same current, and that is I2. This is shown in equation 2: I2 = (Vo-Vin)/(R1+R2).

“No current goes into opamp terminals”
Correct.

“so we don’t need a model for the opamp”
That is correct. I used the model to show that the Op Amp can be considered a voltage-controlled-voltage-source, for ease in understanding and calculation. But, yes, one can apply Thevenin’s Theorem without the model, just by leaving the Op Amp in place.

Another reason for using the model is to show, with another example, how to apply Thevenin’s Theorem for solving circuits with dependent sources.

]]> By: Amp https://masteringelectronicsdesign.com/apply-thevenins-theorem-to-solve-a-negative-resistance-circuit/#comment-3312 Wed, 30 Mar 2011 04:43:31 +0000 http://MasteringElectronicsDesign.com/?p=1773#comment-3312 How do you get equation 1. Please elaborate.
No current goes into opamp terminals, so we don’t need a model for the opamp. correct?
The ckt will reduce to Vin with R1 in series and Vo with R2 in series.

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