Found in a 1988s Radio Electronics, this circuit uses transistors of general use to increase the intensity of signals up to about 30 MHz. The power can be done by battery because the consumption is low.
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...