220V Flashing Lamps: Circuit Diagram & Build Guide

Specifically crafted for festive illumination setups

Replaces outdated heat-sensitive switches

Circuit Diagram

Components:

Device Functionality:

This circuit is designed as a dependable alternative to heat-activated switches utilized for flashing Christmas tree lights. The operation of the device, relying on Q1, Q2 and associated resistors, triggers the SCR. Timing control is achieved through R1, R2 & C1. Adjusting the flashing frequency requires modifying C1’s value instead of R1 and R2 values: select a C1 value ranging from 100 to 2200µF.

Optimal results are obtained with C1=470 or 1000µF and R4=12K or 10K. Considering the minimal power consumption of standard 10 or 20 lamp series-loops typically found in Christmas tree installations (60mA @ 220V typical for a 20 lamp series-loop), compact and affordable SCR devices, such as C106D1 (400V 3.2A) or TICP106D (400V 2A), which are readily available in the TO92 package, can be utilized.

Crucial Information:

For correct operation, it is absolutely essential to utilize high Gate-sensitive SCRs.

Should suitable devices be unavailable, Triacs can be substituted. This circuit will function effectively with larger devices. A recommended Triac type is the widely used TIC206M (600V 4A), although numerous others will suffice. Note that despite the use of a Triac, the diode bridge D1-D4 remains necessary.

This circuit received recognition through publication in ELECTRONICS WORLD "Circuit Ideas", June 2000 issue, page 458