The circuit is from 1980s Linear Technology documentation. The components are of the time and circuit behavior curve is given along the diagram.
This circuit was fond in an old publication of the years 1950. The transistors are germanium types and...
The IC used in this project is not common these days, but if you have one you can build a high...
September 2017 - Littelfuse's Polyswitch SMD Resettable PTCs can now be purchased from Mouser...