This circuit was found in a 1967 American documentation. The circuit uses components of the time, applying to analog lines.
The amplifier shown in figure 2 is based on the MAX9715 integrated circuit from Maxim...
This bird circuit found in several versions on this site uses a light sensor (LDR) firing when the...
This circuit converts sinusoidal signals into squares and can be powered by voltages from 1.5 to 5...