Light control circuit principle circuit diagram

Working principle: The working principle of the application circuit of this device is shown in the figure. During the day, due to strong light, the internal resistance of the photoresistor RG is very small. At this time, a large current flows through RG, causing the transistor VT to saturate and conduct. After VT is saturated, the voltage at the ④ terminal of the controller DM is much lower than 1.6V. Therefore, DM is internally cut off and the lighting lamp H cannot light up.

When night comes, the light dims, the luminous flux shining on RG weakens, the internal resistance of RG becomes larger and larger, and the internal circuit of controller DM gradually opens, so that current flows through the lighting lamp H to make it glow. This circuit is a soft start mode, that is, the filament of the lighting lamp H gradually transitions from red to incandescent state, and it is not easy to flicker when the filament is red.

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