A simulator program uses a wrong or a "typical" spec for a device. Then if you build the circuit it probably will not work if the parts have minimum or maximum spec's. I always look at and design with the minimum and maximum spec's on a datasheet so that every single circuit works perfectly when any passing part is used.

Or you can design a circuit using "typical" spec's and test and sort hundreds of parts and hope that you find some with spec's near "typical".

 

A simulator program uses a wrong or a "typical" spec for a device. Then if you build the circuit it probably will not work if the parts have minimum or maximum spec's. I always look at and design with the minimum and maximum spec's on a datasheet so that every single circuit works perfectly when any passing part is used.

Or you can design a circuit using "typical" spec's and test and sort hundreds of parts and hope that you find some with spec's near "typical".

Or, just ask for "typical" parts when you place your order.

 

Or, just ask for "typical" parts when you place your order.

Then how long will they laugh at you, even when you go there again?

 

My advice is always to check the models you are using first. Old red LEDs had a forward voltage of about 1.6V, the newer ones are somewhat higher, maybe 2V. Blue leds are around 3V. Sometimes the output files will contain the SPICE models used for the components - at least from the better simulators.
And I agree with the post about having to use several models to check tolerances, but this is rarely done outside of professional IC design tools. Each SPICE model should come in three flavours (worst case typical best case) and often critical circuits have to be explored using monte carlo simulations to represent actual production variations - this is likely to give the most realistic answers to how a circuit behaves with real components.
You certainly need to be able to generate your own models to cater for devices that you can't find existing models for; but there are also many device models available if you look. Presumably your simulator, though not one I am familiar with, would let you add devices. If it can't do that it is worth putting out in the trash.