kilowatt dimmer - a tried and tested formula

a tried and tested formula Most light dimmers that are available in the usual electrical goods shops can only handle a fairly small power. A couple of hundred watts is generally the limit and the chance of finding one that can go up to a half kilowatt or so is slim. The simple dimmer circuit shown here can control a power of up to 1 kW. There is not very much to be said about the contents of the cir- cuit. It consists of one triac, one diac and an RC network in which the charging and discharging times of capacitor C2 can be set with potentiometer P1. Noise spikes are suppressed by capacitor C1 and coil L1 Calibration involves setting P1 to maximum resistance and the trim- ming preset P2 so that the lamp is just extinguished. If a lamp of more than 100 W is used the triac must be mounted on a heatsink with a heat transfer rate of about 6 °C/W. For a 1000 W dimmer, suppressor coil L1 must be rated at 5 A (its in- ductance is about 400) and fuse Fl must be rated at 6.3 amps.