The indicated circuit uses an unusual buffer from National Semiconductor. The frequency is given by resistors R1 and R2 as well as capacitors C1 and C2.
In the figure we have the way to connect several 555 to obtain sequential operation. The component...
We found this simple alarm circuit in a 1981 documentation. As we can see, it is a car alarm...
) Found in a 90s Linear Technology documentation, this circuit is a fading of video signals and...