Amazon.com: OPPKEPT 12V RV Dimmer Switch, Upgrade 12/24 Volt DC PWM Dimmer for LED Interior Lights, Halogen, Incandescent, Used for RV, Auto, Camper, Truck, Marine, Boat and Strip Lighting (High Side, Silver) :
110V/220V Light Dimmer Circuit with Active Reset
Automatic Lamp Dimmer Circuit using Triac - Gadgetronicx