PIC12F675 Digital Brightness Controller

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1939
PIC12F675 Digital Brightness Controller

The regulator allows convenient control of the intensity of lighting from light bulbs. It is not suitable for use with typical energy-saving fluorescent lamps and LEDs unless they are adapted for operation with typical dimmers. There are many similar solutions, and probably every electronics engineer has performed a “dimmer” at least once, but this device is characterized by the absence of a potentiometer, which is the most unreliable element. Moreover, unlike typical solutions, no noisy choke has been used. Recommendations: The dimmer can be used e.g. to brighten / darken the bedside lamp in a children’s room.

The light intensity is controlled by means of a pulse width that is variable in width (PWM modulation). Obviously this is a known solution, but as it usually happens when we think something is uncomplicated, it means that we are not aware of the extent of the problem…

If we use PWM to regulate the intensity of LEDs or light bulbs that run on DC voltage, you only need to change the width of the periodic signal at a frequency greater than the inertia of the eye. However, if the lamp is operated with mains voltage (230VAC / 50Hz), the matter is more complicated because the control signal of the lamp must be synchronized with the frequency of the mains.

Otherwise, the bulb may be switched on once at the peak of the sine wave of the supply voltage and the next period at the zero crossing, which would lead to unintended changes in the brightness of the light in the rhythm of the changes in the mains voltage.