An automatic security camera must operate as follows when an intrusion occurs:
1. If the ambient light level is greater than, the shutter is activated.
2. If ambient light is less than, a light source is triggered.
3. When the source lighting reaches, the shutter is triggered.
Design the system and signal conditioning using the following assumptions:
a. The shutter and light source are triggered by TTL logic high signals.
b. A CdS cell with characteristics given in given Figure is used to monitor ambient light level.
c. A photodiode with the characteristics given in Figure b will be used to measure light intensity after the light source is triggered. Explain why the CdS cell could not be used here also.
