This small 1 W amplifier uses a Motorola integrated circuit from the 1970s. The integrated circuit used is uncommon today and the power supply does not have to be symmetrical.
This circuit was obtained in a 1979 publication. The operational amplifier is of the type with...
This circuit was obtained in a 90’s Popular Electronics. The frequency depends on C1, a component...
Because it uses TTL integrated circuits, this siren must be powered by 5 V or as indicated with D1 to...