This traditional configuration with the 555 was obtained in an 80s Hands-On Electronics. The relay is of the sensitive type according to the supply voltage.
September 2016 - can be purchased from Mouser Electronics the new transceivers MAX348x and MAX349x from...
The circuit was found in the February 1992 Radio Electronics magazine. The scale can be changed by...
This amplifier is from a 1973’s Japanese magazine. The transistors are of the time and the power...