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AC 220 Volts Flashing Lamps Circuit

2016-08-14 14:37  
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Especially designed for Christmas tree lamps, Replaces old thermally-activated switches

This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1, R2 & C1. To change flashing frequency do not modify R1 and R2 values: set C1 value from 100 to 2200μF instead.

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 intended for Christmas trees (60mA @ 230V typical for a 20 lamp series-loop), very small and cheap SCR devices can be used, e.g. C106D1 (400V 3.2A) or TICP106D (400V 2A), this last and the suggested P0102D devices having TO92 cases.

Circuit diagram:

AC 220 Volts Flashing Lamps Circuit Diagram


R1 = 100K
R2 = 1K
R3 = 470R
R4 = 12K
R5 = 1K
R6 = 470R
Q1 = BC327
Q2 = BC337
D1 = 1N4007
D2 = 1N4007
D3 = 1N4007
D4 = 1N4007
D5 = P0102D (SCR)
C1 = 1KμF-25V
PL1 = Male Mains plug
SK1 = Female Mains socket

Important Note:

For proper operation it is absolutely necessary to employ high Gate-sensitive SCRs.
If you are unable to find these devices you can use Triacs instead. In this case the circuit operates also with relatively powerful devices. A recommended Triac type is the ubiquitous TIC206M (600V 4A) but many others can work.
Please note that, in spite of the Triac, diode bridge D1-D4 is in any case necessary.

Warning!The device is connected to 230Vac mains, then some parts in the circuit board are subjected tolethal potential!Avoid touching the circuit when plugged and enclose it in a plastic box.

Source: Red Free Circuit Design