My early ideas of what constituted a major contribution was rather less than it is now, so inclusion on this list is not very consistent, but it is a good cross-section of articles I have edited.

• Sorby Research Institute, a G13 rescue and thorough expansion
• Power dividers and directional couplers major expansion
• Conference matrix added Belevitch's contribution and circuit diagrams
• Finsbury Dispensary stub
• RLC circuit major rework
• Joule thief clean up and improved diagram
• Stripline Added some history
• Gyrator, most of generic gyrator section
• Circular reference cleanup
• Heaviside condition rewrite
• Distributed element model big expansion with diagrams
• Nominal impedance complete rewrite and expansion
• Balanced circuit expansion with circuit diagrams, virtually rewritten some very inaccurate text.
• Balanced line Expansion and cable artwork
• Two-port network
• Stub (electronics) Stub is no longer a stub (ha ha)
• Negative resistance Major work on a POV'd article
• Nothing I have written more about nothing than anyone else on Wikipedia
• Paleoclimatology added section on cosmic ray flux
• Wilhelm Cauer major expansion
• Ripple (electrical) major rewrite and expansion
• Loading coil major expansion
• George Ashley Campbell major rewrite and expansion
• Topology (electronics) major rewrite and expansion
• Distributed element model
• Propagation constant major rewrite
• Electronic filter topology
• Hartman effect was a one line stub
• Phantom circuit
• Electronic filters
• Network analysis (electronics) virtually rewritten article
• Admittance
• Ohm's law#ac circuits
• Medical conditions

There is also a minor contributions page, but this is not really kept up to date any longer.