CHRISTMAS FLASHING LIGHT CIRCUIT
Triggering control of the SCR done by Q1, Q2, and related resistors. Timing depends on R1, R2, and C1. If you want to change the frequency, set the C1 value from 100uF to 2200uF instead of modifying the values of R1 and R2, because they already set for the proper current and voltage point. Best performances can be achieved with C1=470 or 1000µF and R4=12K or 10K. A number of 10 to 20 lamp in series for Christmas trees (60mA @ 220V typical for a 20 lamp series-loop) is common, and this low current consumption only need a cheap SCR devices, e.g. C106D1 (400V 3.2A) or TICP106D (400V 2A), and the last, the most recommended is P0102D devices having TO92 case. [Circuit schematic diagram source: ELECTRONICS WORLD "Circuit Ideas", June 2000 issue, page 458].
