Anyone know what causes that "70's smell" from hot electronics from that era?

The odor from my Xcelite tool handles is stronger than the aroma from much of my old electronics gear, yet still vintage. I prefer the electronics between the two. I find it very difficult to dispose of tools. I also like the look on my wife's face when I say "Here, smell this." Of course, this works with many items. She has occasionally indicated my vintage characteristics...😀