PowerEsim- Free on-line switch mode power supply SMPS, circuit and transformer design, calculation, simulation software. More than 100 circuits and topologies are available with real constructed transformer.
It provides a virtual laboratory environment for users to wind and place every single turn of a transformer, and with the help of tens of thousands real modeled component on the market, user can simple pick and place the real component and stuff into the circuit, within a fraction of a second, our server will immediately return the result to the user. It is even faster than modifying prototype in real environment, and more than that is no worry of getting explosion of the prototype on real bench. It is Better than real.
PowerEsim – Free SMPS Switching Power Supply / Transformer Design Software - [Link]