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 circuit is used to cut the “click” in the loudspeaker of amplifiers when they are turned on....
Found in RCA documentation from the 1970s, this circuit is intended for firing thyristors in inverter...
In the figure we have the way to control a TIC series triac with a reed switch. The current in the...