A smoke generating unit for a model train that varies the rate of smoke produce in response to changes in the load on the model train. The smoke generating unit includes a housing, a smoke element and a motor driven fan. The housing can be formed of two sub-housings. The first sub-housing can contain the smoke generating element and the second housing can contain the fan. The smoke element can be a nickel chromium wire. An insulating gasket can be positioned between the sub-housings to thermally insulate the motorized fan from the heat generating element. The motorized fan is controlled by a microprocessor that can monitor the load on the train and control rotation of the fan to correspond to the load on the engine. The load on the train can be the voltage across the engine of the train or the speed at which the train is moving.