Halogen Lamp Dimmer

zero crossing 0 detector 16 12 00 C2 Emm 1u 16V 7 R5 R6 C3 14 3 R9U Tr i 1 The circuit proposed here is suitable for fitting into slide pro- jectors without a dimmer fa- cility (24 V AC fed halogen lamps). With a few small alter- ations, it can also be used for dimming 12 V halogen lamps, but not those in a car, because these are fed from a DC source. The circuit shown in Fig. 1 is intended for operation from a 24 V AC supply, and can handle a lamp load of up to 150 W. For loads up to 250 W, the TIC236 should be replaced by a TIC246. The illumination of the halogen lamp is controlled by applying a direct voltage to pin 5 of dim- mer chip IC, . A voltage of +2.5 V gives maximum illumi- nation, while +5 V results in the lamp being turned off com- pletely. The lamp intensity con- trol range-2.5 V to 5 V-can be extended upwards by de- creasing the value of C2. The TIC246 should be used when the circuit is to control a 12 V lamp that consumes more than 50 W. Figure 2 shows details of...