Incompatibility of compact fluorescent lamps (CFLs) and light-emitting-diodes (LEDs) with conventional light dimmers is a problem for consumers today. This paper proposes a dimmer circuit that is suitable for incandescent bulbs, CFLs and LEDs. Different kinds of lighting devices are studied and tested with AC and DC sources. The proposed dimmer circuit is designed, built and tested with various lighting devices. Experiments are performed in order to observe the electrical characteristic of the dimmer and optical characteristic of the lighting devices when they are used with the dimmer circuit. The experimental results show that the proposed dimmer can be used with these kinds of lighting devices within specific output voltage ranges.