This blog is an "informal" part of NL5 Circuit Simulator website. I'm going to explain what NL5 is, how is it different from popular (Spice-based) simulation tools, and why it worth trying.

It turned out that in Spice-dominating world many people undervalue, or simply are not aware of apparent benefits of simulation with "ideal" components. Some people strongly oppose the whole idea of "ideal" simulation, some people love it. I believe, both "real" and "ideal" simulation approaches make sense, as long as you understand what you are doing: "use right tool for right task".

Thanks.

## Monday, January 1, 2024

## Friday, February 8, 2013

### More Sidelinesoft products

I'd like to introduce couple more Sidelinesoft products related to NL5.

idealCircuit: an analog circuit simulator working with true ideal components. Uses exactly the same unique and robust algorithm as NL5. However, it is simplified as much as possible: very simple and intuitive interface, fewer components and models, no fancy and powerful features that are only useful for specialized applications.

ideal-Z: a simple impedance calculator with graphical schematic entry. Drop components onto the schematic, connect them, set values, and the impedance is calculated instantaneously. Also based on part of NL5 algorithm.

idealCircuit: an analog circuit simulator working with true ideal components. Uses exactly the same unique and robust algorithm as NL5. However, it is simplified as much as possible: very simple and intuitive interface, fewer components and models, no fancy and powerful features that are only useful for specialized applications.

ideal-Z: a simple impedance calculator with graphical schematic entry. Drop components onto the schematic, connect them, set values, and the impedance is calculated instantaneously. Also based on part of NL5 algorithm.

## Tuesday, December 11, 2012

### NL5: borrowing from "digital" world

A new feature is available in NL5 ver. 1.91: Z-transform method for low signal AC analysis.

It is an interesting one: z-domain analysis is typically used for discrete time signals, which is typical for digital circuits, but definitely not for continuous "analog" world. However, it happens that it might be working good enough for continuous periodical (or quasi-periodical) signals as well. Of course, there are some limitations, and the user should be very careful looking at the results.

Simulation time saving is huge: z-transform would be hundred or even thousand times faster than standard "Sweep AC source" method. Such an improvement is probably worth spending some time to learn basics of discrete time analysis, or at least what Nyquist frequency is.

It is an interesting one: z-domain analysis is typically used for discrete time signals, which is typical for digital circuits, but definitely not for continuous "analog" world. However, it happens that it might be working good enough for continuous periodical (or quasi-periodical) signals as well. Of course, there are some limitations, and the user should be very careful looking at the results.

Simulation time saving is huge: z-transform would be hundred or even thousand times faster than standard "Sweep AC source" method. Such an improvement is probably worth spending some time to learn basics of discrete time analysis, or at least what Nyquist frequency is.

## Monday, January 30, 2012

### NL5: step into a real world

What? "Ideal" simulator finally simulates "real" circuits? Not yet...

Components are still ideal. What you can do now is import real scope data, and:

- apply it to you circuit (use it as a "stimulus": voltage or current source signal);

- compare real data with simulation results of an ideal circuit;

- simply use unique NL5 tools and graphical capabilities to explore real data.

Components are still ideal. What you can do now is import real scope data, and:

- apply it to you circuit (use it as a "stimulus": voltage or current source signal);

- compare real data with simulation results of an ideal circuit;

- simply use unique NL5 tools and graphical capabilities to explore real data.

## Wednesday, September 28, 2011

### NL5: simulate circuits that do not exist

The question I've got from the visitor at ECCE-2011 Exposition: "Simulator with ideal components? Why would anybody need components that do not exist?".

The answer is simple and obvious: "To simulate circuits that do not exist".

With standard SPICE-based simulators, a result of the simulation is considered correct if it matches a known real circuit's behavior. What if real circuit does not exist yet? When you design a new principle, a new topology: how can you make sure the idea is feasible? That's what ideal components are used for.

Making everything as simple as possible, you eliminate problems caused by complex models, methods, and algorithms. Starting with ideal components gives you much more confidence that simulation results you see on the screen is true behavior of your circuit - even if the circuit does not exist.

The answer is simple and obvious: "To simulate circuits that do not exist".

With standard SPICE-based simulators, a result of the simulation is considered correct if it matches a known real circuit's behavior. What if real circuit does not exist yet? When you design a new principle, a new topology: how can you make sure the idea is feasible? That's what ideal components are used for.

Making everything as simple as possible, you eliminate problems caused by complex models, methods, and algorithms. Starting with ideal components gives you much more confidence that simulation results you see on the screen is true behavior of your circuit - even if the circuit does not exist.

## Thursday, July 28, 2011

### NL5 Circuit Simulator on Facebook

Visit NL5 on Facebook : read latest news, recommend to friends and colleagues.

## Sunday, April 3, 2011

### Is there any other Simulator with ideal components?

Recently I tested PLECS: the last non-SPICE type simulator for switching circuits I'm aware of. As I expected, it could not simulate none of my test circuits: voltage multiplier, charge pump, circuits with discontinuous inductor current.

I was surprised, since they do have true "ideal" components: switches and diodes with zero/infinite impedance. However, in almost all circuits you have to add either small resistor in series, or large resistor in parallel to those components, so that I don't understand what is the use of those components at all. You cannot, for example, instantaneously connect voltage source and capacitor charged to different voltage: it has to be done through non-zero resistor or limited current source. Same for interrupting current through the inductor. For "ideal" diodes there is special parameter "turn-on threshold", which could be different than diode forward voltage. Some circuits simply stuck in the middle of simulation: same "old good SPICE" convergence problem? This is very confusing.

Originally PLECS was designed to work with MATLAB as Simulink toolbox; stand-alone simulator is kind of a new product. This probably explains very poor interface and lack of many useful and, in fact, required features. For instance, you have to define initial conditions for all capacitors and inductors. I don't think this is acceptable for real engineering tool.

Anyway... so far, I don't know any simulator offering "ideal" component (or even close to "ideal"), and what is more important, providing reliable and fast simulation with those components. I tend to state that NL5 is the only one capable to do that. I'm not aware of any (reasonable) circuits that can not be simulated with NL5: it passed all the tests I designed, and I do not hear any complains from users. They are either happy or shy...

Dear NL5 users, please report problems you have: it would help further improving NL5 and make it more robust and useful for you and for thousands of other users! And please don't forget to download latest builds and revisions: you will definitely find something new and exiting.

I was surprised, since they do have true "ideal" components: switches and diodes with zero/infinite impedance. However, in almost all circuits you have to add either small resistor in series, or large resistor in parallel to those components, so that I don't understand what is the use of those components at all. You cannot, for example, instantaneously connect voltage source and capacitor charged to different voltage: it has to be done through non-zero resistor or limited current source. Same for interrupting current through the inductor. For "ideal" diodes there is special parameter "turn-on threshold", which could be different than diode forward voltage. Some circuits simply stuck in the middle of simulation: same "old good SPICE" convergence problem? This is very confusing.

Originally PLECS was designed to work with MATLAB as Simulink toolbox; stand-alone simulator is kind of a new product. This probably explains very poor interface and lack of many useful and, in fact, required features. For instance, you have to define initial conditions for all capacitors and inductors. I don't think this is acceptable for real engineering tool.

Anyway... so far, I don't know any simulator offering "ideal" component (or even close to "ideal"), and what is more important, providing reliable and fast simulation with those components. I tend to state that NL5 is the only one capable to do that. I'm not aware of any (reasonable) circuits that can not be simulated with NL5: it passed all the tests I designed, and I do not hear any complains from users. They are either happy or shy...

Dear NL5 users, please report problems you have: it would help further improving NL5 and make it more robust and useful for you and for thousands of other users! And please don't forget to download latest builds and revisions: you will definitely find something new and exiting.

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