Halogen-lamp-dimmer

Description: This circuit is designed for integration into slide projectors that lack a dimmer functionality, specifically for use with 24-V AC fed halogen lamps. With minor modifications, it can also be adapted for dimming 12-V halogen lamps, although it is not suitable for automotive applications due to the direct current source used in vehicles. The circuit illustrated in Figure 50-1a is intended to operate from a 24-V AC supply and can manage a lamp load of up to 150 W. For loads reaching up to 250 W, the TIC236 component should be substituted with a TIC246. Additionally, the figure details the connection of a potentiometer to the intensity control input of the TCA280A. The voltage divider formed by resistors R10, P1, and R11 is installed externally and can be powered from the stabilized voltage available at pin 11 of IC1. The minimum and maximum brightness levels of the lamp are set by resistors R10 and R11, respectively.

This circuit offers a practical solution for controlling the brightness of halogen lamps in slide projectors that do not have built-in dimming capabilities. The primary operational component, the TCA280A, functions as the main control unit, allowing for precise adjustments of lamp intensity. The circuit's design is optimized for a 24-V AC input, making it robust for typical projector applications.

To enhance the dimming functionality, a potentiometer is integrated into the circuit, providing an adjustable resistance that influences the voltage divider formed by R10 and R11. This setup allows the user to fine-tune the brightness levels, with R10 setting the minimum intensity and R11 determining the maximum. The external configuration of the voltage divider ensures that the circuit can be easily modified or calibrated to meet specific user requirements or lamp characteristics.

For higher power applications, the circuit can accommodate loads up to 250 W by replacing the TIC236 with a TIC246, which provides additional current handling capabilities. This flexibility allows the circuit to be used with a variety of halogen lamps, ensuring compatibility with different projector models and operational needs.

Overall, this circuit design exemplifies a user-friendly approach to integrating dimming control in slide projectors, enhancing the versatility and functionality of lighting solutions in presentation environments.This circuit is suitable for fitting into slide projectors without a dimmer facility as witb 24-Vac fed halogen lamps. With a few small alterations, it can also be used for dimming 12-V halogen lamps, but not those in a car, because these are fed from a de source.

The circuit shown in Fig. 50-1a is intended for operation from a 24-Vac 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. Figure shows detail of the connection of a potentiometer to the intensity control input of the TCA280A. Voltage divider RlO-Pl-Rll is fitted externally and can be fed from tbe stabilized voltage available at pin 11 of IC1.

The minimum and maximum intensities of the lamp are determined by RlO and Rll, respectively.