In summary, there are a few free circuit testing programs available, such as SPICE-like freeware from chipmakers like Linear Technologies and TI, and the ICAPS Spice modelling software from INTUSOFT. These programs offer features such as graphical displays of DC initial condition voltages, parametric sweeps, and a wide range of component libraries including diode models. Some programs have limits on the number of components or nodes in a circuit, so it is important to check before use.
Does anyone here know of a good circuit testing program that is free that includes diodes? I need to find certain voltages on specific points on a circuit, and I can't find anything good out there that can help.
INTUSOFT (http://www.intusoft.com/) do a fully functional evaluation of their ICAPS Spice modelling software.
It is limited to 20 components in circuit but does allow you to group components into sub-circuits of up to 20 components each that boost the amount of actual components you can model.
It is all graphical and allows you to display the DC initial condition voltages on your schematic.
Or you can do parametric sweeps to determine how voltages change with changing component values.
The standard library has over 1500 components and has both diode primatives that you can create your own diode model based on datasheet values and a wide range of commercial diode models.
This reminds me that the TI simulator had an upper limit on the number of nodes in the circuit (less than 50, I think), but the LT simluator had no limit.