This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
We found this circuit in the October 1978 issue of Radio Electronics magazine. The magazine...
This siren configuration using the 555 has already been explored in other circuits on this site. In...
VR can be from 50 to 220k it is recommended to connect a 100-ohm resistor in series. The lamp may...