Light-control electronic switch, it’s "open" and "off" is by the SCR on and blocks to achieve, while the SCR on and blocks and is subject to the brightness of natural light (or artificial light) The size of the control. The device is suitable as a street or other public places dormitory hallway lights off at night to play the role of light control, to save electricity.
Circuit as shown above, 220V AC through the lamp after H and full-bridge rectifier into DC pulsating voltage, as a positive bias, added to the SCR and R branch on the way VS. During the day, the brightness is greater than a certain degree, the end of the photodiode D showed resistance state = 1KO, the transistor V cut-off, no current output of the emitter, for lack of one-way VS SCR trigger current and blocked. At this point the current flowing through the lamp H = 2.2mA, H can not light the lamp. DW resistor R1 and Zener diode does not exceed the transistor V bias voltage 6.8V, the protective effect of the transistor. Night, the brightness is less than a certain degree, present a high impedance state photodiode D = 100KO, the transistor V the forward emitter voltage of about 0.8V, the SCR trigger conduction VS, H light bulb. RP is the early morning or evening options to achieve the brightness switch conversion components. Installation and Commissioning: Installation, Welding good will into the transparent plastic box printed and fixed, lights it with a controlled H series, and it is the window facing the tent or house light and bright space more , less than 3 m to avoid direct exposure to light at night. Should be evening when debugging, RP resistance adjusting the size of the controlled lamp brightness H began in the appropriate light.