This very low frequency amplifier has a gain of 1,000 and was found in a 1967 documentation. The circuit is suitable for detecting explosions, distant echoes and seismic vibrations.
In this circuit of a 1968 publication the unijunction may be 2N2646 and the transistor BC548. The...
The purpose of this circuit is to improve a trigger circuit using a zener diode. The circuit was...
This interesting circuit of the American publication Electronics Handbook Volume XIII 1993 shows a...