This circuit was found in a RE Experimenter Handbook from the 90's. The components are of the time, rare nowadays, except the 555 and 4017.
This TTL siren is formed by two oscillators using each two Gates of a 7400. Frequency or the...
The bridge diodes of this circuit, found in a 1967 publication, are according to the motor...
This well-known configuration was found in a 1982 publication. Other operational amplifiers can be...