The circuit is based on the IC1 that is 555, for the creation of alternate flashes from the two led D1-2, that can be also different colour. The frequency of alternation can be regulated from the trimmer R3 and from the C1, if changes his capacity. The supply can become from a battery or from one separate power supply. A use of circuit is creation '' clue '' of alarm. Exists the possibility is connected at the same time with D1-2, the optocoupler IC2-3, with that we externally drive circuits, for various uses.
R1-2= 1.5Kohm C2= 100nF 63V D1-2= LED 3mm
R3= 250Kohm trimmer C3= 100uF 16V BATT= 9V Battery
R4-5= 470 ohm IC1= 555 S1= Push Button or switch on-off
C1= 10uF 16V IC2-3= 4N25 optocoupler