Digital clock

[Mark Hennessy]

BTW., they do have temperature control - its built into the RF characteristics of the tip - the tips are preset for different temperatures - you buy tips based on both their temperature and shape

Yes, they use the Curie effect. There is a video here that explains it: https://www.youtube.com/watch?v=S9Wmqc9O24w#t=54

Of course, the TCP system also exploits the Curie effect, albeit in a different way.

As did recordable MiniDisc