Talk:Gyrator

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Contents 1 C and L mistake 2 Polarity of opamp 3 As a filter or as just an impedance to ground? 4 electrical network is smaller than a electrical network 5 Error in description? 6 Gyrators are 2-port elements. Isan't it?

[edit] C and L mistake

The "C" shown in the simulated circuit should be an "L" (inductance), the description won't make sense otherwise... --Palapala 22:34, 27 Feb 2004 (UTC)

I fixed it but the picture isn't updating for some reason.

see http://en.wikipedia.org/upload/archive/1/14/20040227215433%21Gyrator.png

if you know how to fix it please do. - Omegatron

I reverted your image to the one you want, I hope.

It is http://en.wikipedia.org/upload/archive/1/14/20040228164914%21Gyrator.png

It has resistors R and R(subscript L) in the top, Gyrator circuit, while the bottom Simulator circuit has one resistor R and the inductor L with the equation L=R(sub L)RC.

Does that match the description here?

"From the diagram, the inductance L of the gyrator is equal to R1R2C. Given the inductance to be simulated and the resistance values, the capacitance can be found by C = L / (R1R2)."

R1 is R(sub L) and R2 is R?

Wikibob 19:17, 2004 Feb 28 (UTC)

Yes, Wikibob, thanks for fixing it. I fixed the equations too. Everyone like it now? R_L is now the resistance a real inductor would have. - Omegatron

[edit] Polarity of opamp

The SRL external link has the polarity of the opamp reversed. Does anyone know which is correct? I suppose I could stop being lazy and calculate it myself... - Omegatron

Ok. I did the calculations, and it works. I've also found several other circuits with the same polarity. Only that one example has it reversed. It is vaguely similar to a standard difference amplifier, with a capacitor and a zero ohm feedback resistor. - Omegatron

The circuit in this article (with *negative* feedback) works. I'm almost certain that the other circuit (with *positive* feedback) can't possibly work. But someone should really confirm.

I remember doing calculations with both and finding that they both work, but I could have made dumb assumptions. I will check again some time. - Omegatron 14:03, Aug 3, 2004 (UTC)

Conventional analysys of op-amp circuits relies on the assumption that the voltage difference between the two inputs will become negligable. This is only true if the feedback is negative. If you use postive feedback you end up with a schmitt trigger. Plugwash 02:02, 14 March 2006 (UTC)

Of course.  :-) — Omegatron 03:41, 14 March 2006 (UTC)

I checked in a simulator and it seems to work either way. Pfalstad 06:39, 14 March 2006 (UTC)

[edit] As a filter or as just an impedance to ground?

I noticed that the voltage at the output of the op-amp and at the inductor are the same, but I don't know if it's worth mentioning. The same effect can be had with just the R and C, so it is not too important, right? - Omegatron

Perhaps adding another "output node" circle to the schematic diagrams would be sufficient.

I had that at first, but thought it would be too distracting and people would think it was meant to be used as a filter. It is meant to act as an inductor to ground as part of a simulated LC filter. - Omegatron 14:03, Aug 3, 2004 (UTC)

[edit] electrical network is smaller than a electrical network

Currently the article claims that "an electronic circuit, which is typically much smaller than a tabletop electrical circuit."

Since *both* electronic circuit *and* electrical circuit are now re-directs to another article, normally I would change them to point directly (rather than indirectly through the redirect) to that other article:

"an electrical network, which is typically much smaller than a tabletop electrical network."

Huh ?

--DavidCary 19:25, 2 Aug 2004 (UTC)

If I were fixing a double redirect, I would probably leave the wording the same, and just change where the link points. You can't always change the wording to wherever it redirects. Some redirects are just conceptual redirects, instead of words that could literally be interchanged. I changed it like this:

Its primary use is to simulate an inductive element in a small electronic circuit or integrated circuit, which is typically much smaller than a tabletop circuit.

- Omegatron 14:03, Aug 3, 2004 (UTC)

[edit] Error in description?

It appears that the line "In other words, it can make an inductive circuit behave capacitively," should actually read "In other words, it can make a capacitive circuit behave inductively,"

It wasn't really an error, because the sentence said invert but the main use is to simulate inductors. Thank you for your contribution. Ancheta Wis 13:07, 22 Nov 2004 (UTC)

[edit] Gyrators are 2-port elements. Isan't it?

I think some mistake happened because of different definitions. As I know as a Mechatronic student, Gyrators are two-port elements that have the relations v2= k i1 and v1 = k i2. Most of gyrators use Hall Effect. For more information please refer to:

http://www.paritycomputing.com/jpdfs/ieee/ssc/ireissc3/1959002/01feb/0024grub.pdf

and

"gyrator." McGraw-Hill Encyclopedia of Science and Technology. The McGraw-Hill Companies, Inc., 2005. Answers.com 02 Mar. 2007. http://www.answers.com/topic/gyrator

I am eagerly ready to hear other’s opinions. --Anooshahpour 07:58, 2 March 2007 (UTC)

There is no mistake with definitions, 'gyrator' is the only name I've heard this circuit refered to in the electronics industry. However, there definitely are other devices which are also known as a gyrator. So far we have 3 types:

• Impedence inverter circuit (This article)
• "Hall Effect Gyrator" which uses a slab of semiconductor through which a current (usually DC) flows, these are used in hall effect sensors
• "Microwave gyrator" - which causes phase changes in microwave signals, by using a ferrite device. These are used in phased array radar.

Perhaps a disambiguation page is in order, when there are articles for other types. --Ozhiker 09:47, 2 March 2007 (UTC)