This circuit activates a buzzer when the voltage applied to the input falls below a preset value in R1. The circuit is from an 80's American documentation.
The circuit shown in the figure was suggested by National Semiconductor in its 1994 Linear...
In the figure the well-known basic configuration of relaxation oscillator with unijunction...
This 2 meter (144 MHz) preamplifier is intended for use with portable transceivers. The...