This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
This circuit is from the 1990 Motorola Linear Databook. The circuit can be applied to other...
We found this circuit in an old documentation for hams. In it we have the way to use a varicap to...
We found this circuit in a 1972 documentation. The transistor, in fact, is a unijunction that can...