Light metering stationery case light metering circuit

Published:2011/7/4 1:01:00 Author:Christina | Keyword: Light metering, stationery case, light metering circuit | From:SeekIC

The light metering circuit of the light metering stationery case is as shown in the figure. This circuit uses the 2CRll silicon photocell as the light metering component, and this 2CRll silicon photocell is installed on the surface of the stationery case to feel the light intensity. The VD1 and VD2 are two light-emitting diodes that can be used to indicate the strength of the light. When the illumination is less than 10Olx, the voltage which is produced by the silicon photocell is small, the VT1's tube voltage is large or it is in the cut-off state, the two light-emitting diodes VD1 and VD2 will not turn on; when the illumination is between 100-20Olx, the voltage that is produced by the silicon photocell will increases, the voltage drop of VT1 reduces, the light-emitting diode VD2 turns on, this means the illumination is moderate.



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