Staircase light controller

staircase light controller EE 119 July/August 1986 991 a piece of veroboard and fitted into an ABS mains wiring junction box, as a replacement of one of the switches in the hotel circuit. As many points in the circuit are at mains potential, due precautions should be taken in the construction and wiring of the controller. Note that Si should be rated at 240 V AC, in view of the necessary isolation with respect to the mains voltage. Trii and Tri2 require no heatsinks if the bulb is rated at 100 W or less, while the maximum power rating for the triacs is about 400 W. This circuit has been designed to function as an automatic switch-off fa- cility on the lines of the well-known hotel switch circuit, i.e. the combi- nation of two switches and a single light. While not exactly a replace- ment of any of the two changeover switches at the top and the bottom of the stairs, the proposed controller may be fitted into one of the relevant junction boxes in which a live mains line is available...