Which is the best and most realistic electronic circuit simulator?

Is there software or service for simulating electronic circuits, but such that one can also download a model of special transistors, for example if I want to insert a transistor c945 or bc547 into the simulation scheme?

Thanks.

Depends on what type of simulation you are looking for.

For example, is it?
-Digital
-RF
-Linear (s-parameters)
-Non-Linear (SPICE Models)
-Full 3D EM
-Layout (DRC)

It's cheapest to narrow it down to 1. If you want a simulator that handles all these then expect to pay prices up in the small condo range.

Various versions of Spice probably fulfill your request. I use LTSpice IV because it is free, handles linear and non-linear situations, and mostly does what I want. When it doesn't fulfill my needs, my inexperience is probably the problem.

For example, if I want to simulate this:

Circuit.png

what should i put in place of that transistor bc547 in that picture?
How to load it?
Transistor.png

Circuit.png

Transistor.png

Any general purpose NPN model will do.

But there must probably be a model of such a transistor for download from some site for simulation and then load in simulation software.

How will the software know that it is specifically a bc547 transistor, that it is not any transistor?

Many semiconductor manufacturers have Spice models available for their products. Simulators typically also have provisions for building one's own model from published parameters.

The BC547 is a common device, so for something like LTSpice, its model is probably already in the base distribution: LTSpice-Libraries/standard.bjt at master · evenator/LTSpice-Libraries · GitHub

Finally "the best" by some measure is often something that is good enough for purpose while minimizing complexity which may be contrary to "the most realistic".

What do you hope to learn from the simulation using a BC547 model, that you could not learn using a 2N3904 or 2N2222 model?

I also need a transistor c 945, and it's gone here: LTSpice-Libraries/standard.bjt at master · evenator/LTSpice-Libraries · GitHub

I use LTSpice. The libraries are mostly third party, so it can be tedious to find models - but they are mostly in there. You should be able to find a pair of general purpose NPN/PNP somewhere in there.

You keep saying, "...but I need this or that exact transistor". Why? Are you depending on some specific parameters? This is not something tricky like an UHF preamplifier. It's an LED driver.

Do you have any idea what I could type into web search to get those third party scripts for the corresponding transistors or that kind of transistor sets, for example for LTSpice software (when we are already with it)? What are such libraries called?

The best tool is only as good
as you are at using it!

Suggest you forget about simulators and use hardware directly.

Don't forget you can look up the characteristics of devices in data sheets ;).

No technical PMs.
If you are asked a question, please respond with an answer.
If you are asked for more information, please supply it.
If you need clarification, ask for help.

Yes, but all this information will help many to whom, not only to me and for many things.

Aleksandari:
Do you have any idea what I could type into web search to get those third party scripts for the corresponding transistors or that kind of transistor sets, for example for LTSpice software (when we are already with it)? What are such libraries called?

They are included in the standard installation.

They are included in the standard installation.

And if need something out of the standard?

This is getting tedious, :astonished:

The circuit you indicate is using a transistor as a switch, There is no need whatsoever to expect the simulator to tell you whether it will work or not with a particular transistor - that is something you determine from studying the characteristics in the datasheet and understanding the circuit. If you can not do that, there is no point using a simulator.

Aleksandari:
And if need something out of the standard?

You don't. You are doing a bog standard job that any general purpose transistor will do. Any small signal device will behave like any other, you have already been given alternatives, but here are some more:

BC107, BC108, BC109. All long established and should be in any device library. I tend to use BC547 but only because I have them in bulk.

Aleksandari:
And if need something out of the standard?

You can create a new model by specifying the parameters and optionally the PCB footprint.

The community here is basically saying... when working with DIGITAL logic circuitry, don't agonize over the different small-signal transistors. Most times people specify a BC547 or 2N2222A because 1) they have them in the junk box 2) their basic characteristics are within the parameters of the needed solution (which would be the same if it were driving an LED or RELAY or something similar)

When we say "use a 2N2222A", as in the diagram above... it's not a requirement to use that exact part... it just means "use a part that is reasonably close to the same characteristics". An example of a BAD replacement for a 2N2222A is a 2N3055. Where in this case, a 2N3055 behaves VERY differently.

PS: Much of what I said does not apply to ANALOG circuitry, where transistor behavior is much more particular and depends on being used in the linear-mode. FWIW, Google Jim Widlar to see a god of the analog world.