This video shows a modification of the Ralin firmware ( https://github.com/Ralim/ts100) of the TS100 soldering iron ( http://amzn.to/2fnl8OE )
It adds an oscilloscope functionality to the iron.
For more details visit https://befinitiv.wordpress.com/2017/09/26/ts100-oscilloscope-hack/
Sources (still under heavy development) can be found under https://bitbucket.org/befi/ts100scilloscope .