This oscillator version is from an RCA documentation from the 1970s. Transistors support modern equivalents and the power can be supplied in a voltage range of 5 to 12 V. For Q2 we suggest the BD136.
This amplifier with gain control was obtained in a documentation from Signetics of the 80's....
Found in 1960's Radio Electronics, this circuit provides an audio tone that depends on the logic...
This circuit can be used as a signal when powered by a car battery, as it also works with 12 V, or...