Elsie 2.80 can be downloaded from our website for free. The program belongs to Education Tools. The actual developer of the software is James L. Tonne.
From the developer:
Elsie ™ is an uncommon commercial-grade lumped-element ("L-C") electrical filter design and network analysis program, directed toward the engineer, technician or hobbyist involved in that line of work.
You may want to check out more software, such as SRIM, StatPlus or EarthBrowser, which might be similar to Elsie.