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.
This shortwave preselector was found in the July 1994 issue of Radio Electronics magazine. The...
This photoelectric cell light relay was found in Radio Electronics magazine from April 1958. The...
This signal attenuator was suggested by Electronics Now magazine in April 1999. The circuit is...