An implementation of virtual inductor (aka Artificial inductance) is presented in this video. For more Circuit examples see: Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html Negative Inductance Design Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html Converting Capacitance to Inductance th-cam.com/video/weIHG45G6Pg/w-d-xo.html Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html Analog Computer circuit that solves Differential Equation th-cam.com/video/HeZRtnRXpEI/w-d-xo.html To see more op amp and analog circuits examples please check analog design playlist th-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html I hope these Circuit engineering and analysis videos are helpful.
love it, love it more because it depends on a capacitor which kinda makes the circuit more impressive because the capacitor in many ways isn't an inductor, in the same way a mom isn't a dad, even though they sleep together. You sir are amazing.
Glad that you liked this minimal-component analog circuit that for target frequency range of interest can implement a large virtual inductor with just one operational amplifier and one main capacitor. The 100 ohm potentiometer can also be removed if just a fixed inductance value is desired.
Would it be possible to use this for LC filters where the inductors are in series with each other, like the Hammond Scanner Vibrato case? If so, the output of the opamp would be connected to the input of the next circuit instead of ground? Or how do I wire it?
Glad that this Impedance converter circuit is useful. There are many ways to realize (simulate) a virtual inductor. The input port of this circuit acts as a virtual inductor with one terminal grounded. So you can for example wire a series capacitor to the input (forming a series LC tank). If you are interested in virtual floating inductance, then this circuit is not the proper design. Instead, I suggest the virtual floating inductor design for example using circulating amplifier: Simulated Floating Inductor Design with Circulator Amplifier th-cam.com/video/weIHG45G6Pg/w-d-xo.html Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html Negative Inductance Design by Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html I hope these additional impedance Converter and Gyrator Circuit examples are helpful.
That's a good question. Theoretically yes assuming frequency of oscillation is well within the frequency range of operation for the designed virtual inductor. For example, in this video, the designed artificial inductor is for Audio application (20 Hz to 20 kHz). It is important to make sure circuit components (resistors, capacitors) are selected properly to achieve the target frequency of operation for the virtual inductance. Op Amp should be a low-noise, very low-offset (say CMOS) operational amplifier (for example see the Texas Instruments Op Amp suggested in the video. It is also recommended to have a say 47pF or 100pF capacitor between OpAmp's output and negative input terminal (to make circuit more stable). To see alternative techniques of designing simulated inductor including a floating virtual inductance see: Converting Capacitance to Inductance th-cam.com/video/weIHG45G6Pg/w-d-xo.html Negative Inductance Design Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html I hope this explanation is helpful in answering your question.
As always .. excellent video.... Just wondering how we can put this to a practical use ? can you share a small block diagram of a possible application circuit please...
My pleasure & Thank you! regarding your questions, A sizable virtual inductance (say as large of few Henry) can be realized using this circuit for a reasonable range of frequencies (say 20Hz to 20 KHz for Audio Application) by proper selection of circuit components. In practice, such large inductors might not practically exist, or might be very expensive, bulky, noisy with large THD. While a properly designed virtual inductance might be able to resolve such issues. A possible use case example is in parallel LC oscillator. There are alternative circuit techniques to design an artificial inductor including a floating virtual inductance as discussed in the following videos: Converting Capacitance to Inductance th-cam.com/video/weIHG45G6Pg/w-d-xo.html Negative Inductance Design Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html I hope this is helpful.
Good questions. Resistor connected to negative terminal is for impedance matching purposes of the two input terminals to minimize input offset current and common mode effects of operational amplifier. Output resistor can be removed but depending on the selected op amp, might help with circuit stability. It is a good practice to check the datasheet of selected op amp regarding additional required passive components (resistors and capacitors) connected to op amp terminals for proper op amp circuit operation.
Thanks for your interest in this circuit and good question. The concept is similar but Gyrator is a two port device as discussed in the following examples: Impedance Converter Design with Op Amp (Gyrator) th-cam.com/video/jPudh9yqDH4/w-d-xo.html Gyrator Circuit Design with Operational Amplifier th-cam.com/video/cWjRvnAJbUg/w-d-xo.html Negative Inductance with Gyrator th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html , Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html Impedance Converter Gyrator with Transformer to convert Capacitance to Inductance th-cam.com/video/GVLC_pqSETA/w-d-xo.html I hope these additional Gyrator circuit examples are interesting.
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An implementation of virtual inductor (aka Artificial inductance) is presented in this video. For more Circuit examples see: Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html
Negative Inductance Design Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html
Converting Capacitance to Inductance th-cam.com/video/weIHG45G6Pg/w-d-xo.html
Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html
Analog Computer circuit that solves Differential Equation th-cam.com/video/HeZRtnRXpEI/w-d-xo.html
To see more op amp and analog circuits examples please check analog design playlist th-cam.com/play/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt.html
I hope these Circuit engineering and analysis videos are helpful.
love it, love it more because it depends on a capacitor which kinda makes the circuit more impressive because the capacitor in many ways isn't an inductor, in the same way a mom isn't a dad, even though they sleep together. You sir are amazing.
You are welcome. Glad that you liked this virtual inductance (aka artificial inductor) implementation circuit video.
Nice way to get a large value inductive reactance with a handful of parts at a fraction of the size of a real inductor.
Glad that you liked this minimal-component analog circuit that for target frequency range of interest can implement a large virtual inductor with just one operational amplifier and one main capacitor. The 100 ohm potentiometer can also be removed if just a fixed inductance value is desired.
Would it be possible to use this for LC filters where the inductors are in series with each other, like the Hammond Scanner Vibrato case?
If so, the output of the opamp would be connected to the input of the next circuit instead of ground? Or how do I wire it?
Glad that this Impedance converter circuit is useful. There are many ways to realize (simulate) a virtual inductor. The input port of this circuit acts as a virtual inductor with one terminal grounded. So you can for example wire a series capacitor to the input (forming a series LC tank). If you are interested in virtual floating inductance, then this circuit is not the proper design. Instead, I suggest the virtual floating inductor design for example using circulating amplifier:
Simulated Floating Inductor Design with Circulator Amplifier th-cam.com/video/weIHG45G6Pg/w-d-xo.html
Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html
Negative Inductance Design by Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html
Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html
I hope these additional impedance Converter and Gyrator Circuit examples are helpful.
@@STEMprof Thank you so much for your in depth answer.
@@sharptrickster You are welcome. 🙋♂️
Can it be used to substitute Inductor in LC oscillator?
That's a good question. Theoretically yes assuming frequency of oscillation is well within the frequency range of operation for the designed virtual inductor. For example, in this video, the designed artificial inductor is for Audio application (20 Hz to 20 kHz). It is important to make sure circuit components (resistors, capacitors) are selected properly to achieve the target frequency of operation for the virtual inductance. Op Amp should be a low-noise, very low-offset (say CMOS) operational amplifier (for example see the Texas Instruments Op Amp suggested in the video. It is also recommended to have a say 47pF or 100pF capacitor between OpAmp's output and negative input terminal (to make circuit more stable). To see alternative techniques of designing simulated inductor including a floating virtual inductance see:
Converting Capacitance to Inductance th-cam.com/video/weIHG45G6Pg/w-d-xo.html
Negative Inductance Design Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html
Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html
I hope this explanation is helpful in answering your question.
As always .. excellent video....
Just wondering how we can put this to a practical use ?
can you share a small block diagram of a possible application circuit please...
My pleasure & Thank you! regarding your questions, A sizable virtual inductance (say as large of few Henry) can be realized using this circuit for a reasonable range of frequencies (say 20Hz to 20 KHz for Audio Application) by proper selection of circuit components. In practice, such large inductors might not practically exist, or might be very expensive, bulky, noisy with large THD. While a properly designed virtual inductance might be able to resolve such issues. A possible use case example is in parallel LC oscillator. There are alternative circuit techniques to design an artificial inductor including a floating virtual inductance as discussed in the following videos: Converting Capacitance to Inductance th-cam.com/video/weIHG45G6Pg/w-d-xo.html
Negative Inductance Design Op Amp Impedance Converter th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html
Operational Amplifier Gyrator Network Circuit th-cam.com/video/2KpjAytRBpc/w-d-xo.html
I hope this is helpful.
Why are resistors required at the negative input of the opamp and between the output and the ground?
Good questions. Resistor connected to negative terminal is for impedance matching purposes of the two input terminals to minimize input offset current and common mode effects of operational amplifier. Output resistor can be removed but depending on the selected op amp, might help with circuit stability. It is a good practice to check the datasheet of selected op amp regarding additional required passive components (resistors and capacitors) connected to op amp terminals for proper op amp circuit operation.
Isn't this just a gyrator? I remember studying these back in 1988 at University.
Thanks for your interest in this circuit and good question. The concept is similar but Gyrator is a two port device as discussed in the following examples:
Impedance Converter Design with Op Amp (Gyrator) th-cam.com/video/jPudh9yqDH4/w-d-xo.html
Gyrator Circuit Design with Operational Amplifier th-cam.com/video/cWjRvnAJbUg/w-d-xo.html
Negative Inductance with Gyrator th-cam.com/video/GF_Mun_Mkyo/w-d-xo.html ,
Active Inductor with Op Amps th-cam.com/video/6IYz4iaa05c/w-d-xo.html
Impedance Converter Gyrator with Transformer to convert Capacitance to Inductance th-cam.com/video/GVLC_pqSETA/w-d-xo.html
I hope these additional Gyrator circuit examples are interesting.