This is a 220V LED flasher circuit which is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. This a cheap circuit and easy to build.
R1_________ 100K R2,R5______ 1K R3,R6______ 470R R4_________ 12K C1_________ 1000µF 25V D1-D4______ 1N4007 D5_________ SCR P0102D Q1_________ BC327 Q2_________ BC337 SK1________ Female Mains socket
How the circuit works:
The device formed by Q1, Q2 and related resistors triggers the SCR. The flashing frequency is provided by R1, R2 and C1. To change flashing frequency value, just set C1 value from 100 to 2200µF, don’t modify R1 and R2.
Best performances are obtained with C1=470 or 1000µF and R4=12K or 10K. Due to low consumption of normal 10 or 20 lamp series-loops, very small and cheap SCR devices can be used, e.g. C106D1 or TICP106D.