The composition of the dimmers
Normal dimmers for the development trend only apply to the dimming of the heat source. The dimmer structure of the gas discharge lamp is more complex. Such as fluorescent lamp dimmer, adjust the light by means of impedance variable circuit or change input voltage, the range is too small. If use high power or field effect transistor, adopts the form of the electronic ballast, can greatly improve the fluorescent and other discharge lamp dimming performance, increase the dimming range.
The trigger circuit consists of a relaxation oscillator composed of semiconductor discrete components and a single chip integrated trigger composed of triggered diodes. It must produce with the input voltage phase shift in each cycle need conduction Angle synchronized trigger pulse, has a certain trigger power, achieve the goal of trigger and reliable. Control circuits are controlled by a variety of control triggers, such as photoelectric control, audio control, program control and feedback control. Feedback system In order to achieve constant voltage and constant current, short circuit protection, such as purpose, adopt closed-loop protective measures to form a feedback system, in order to satisfy different quality requirements.
The commonly used thyristor is composed of the main circuit, the trigger circuit, the control circuit and the feedback system (FIG. 1), which is suitable for the lighting of the heat radiation source. The main circuit consists of a bidirectional or unidirectional, controlled silicon in parallel to the source circuit. The input is the communication sinusoidal wave, which is the sine wave of the missing angular phase in the output of the thyristor. As shown in figure 2, the waveform must contain high harmonics, which produce radio interference. Second, the effective value of its output voltage is nonlinear with the leading Angle.
