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.
The normal use of a 4520 as a divide-by-16 counter is shown in Figure bellow. In the normal...
This flasher was found in an 80's Electronic Engineering but can be easily implemented with modern...
This micro-transmitter for the FM band was found in documentation from the 90s. The circuit is...