We found this circuit in an old documentation. It has a thermally compensated voltage reference. The circuit is powered by a single source.
This circuit produces a square wave signal with the frequency determinated by R1 and C1. The upper limit...
The FET can be a BF245, and the other transistors can be the BC548 and BC558 in this simple AM...
In this circuit, from a 1977 publication, we have the traditional version of a filter tuned to 1...