This circuit was found in documentation from the 1970s. The transistor supports modern equivalents. L1 with C4 determines the frequency range of the signals that will be produced.
This traditional configuration with the 555 was obtained in an 80s Hands-On Electronics. The relay...
This two-transistor circuit is from a Radio Electronics magazine from April 1965. The transistors are...
This circuit was found in a 90s Hands On Electronics. The semiconductor component is a Triac of...