Automation in lighting can be best illustrated by a photocell switch. This purpose behind the design of this switch is to have it automatically turn an illuminator on or off, depending on the light conditions. Say, for instance, a photocell switch turns the illuminator on at dusk, and switches it off during the daybreak.
How The Switch Works
The process behind a photocell switch circuit involves a photoresistor. This photoresistor alters the resistance of the electron flow, depending upon the intensity of light that it is subjected to. When the intensity of light is high, it offers zero resistance to the electron flow. However, when there is no light falling on it, it offers 100 percent resistance. This response is sent to the relay that makes a binary decision depending upon the signals sent to its base. Thus, if the light intensity falling on the photocell switch is high, it would cause the electromagnet to energize and to switch off the lighting system. However, low light intensity would again deactivate the system.
This signal to the electromagnet is sent via the transistor, which is a semiconductor that contains a base, collector, and emitter. If low quantity of current gets transferred to the base from the emitter of a transistor, then a large amount of it can be transferred to the collector from emitter. Therefore, if the base remains grounded, then the switch turns on; whereas, in the opposite scenario, it would be turned off. For the same reason, if light falling on photocell switch is of high intensity, then the transistor would be turned on and the current would flow from the emitter, all the way to the collector. In case of darkness, this function is altered and hence, transistor turns off on its own.
Application Of The Switch
Home Indoor And Outdoor Lighting
The photocell switch lighting is used for various indoor and outdoor purposes. But for both uses, the switch functions in the same way. As mentioned, this adjustable photocell switch is used to control the lighting using a timed cycle, which automatically turns the lighting system on or off at the designated time. The adjustments can be made using the digital or analog timer, which usually comes with the light switch product.
Car Headlights
The said photocell switch can also be used for short-term lighting, as in the case of car headlights where the switching delay is about 30 to 35 seconds. The same automatic on and off switch system for home is followed.
Street Lights
Another valuable application of the photocell switch is the street lighting. The street lights turn on and off automatically on fixed time intervals. The timer can be either adjusted manually, or they can be set automatically in accordance with the surrounding illumination. When the luminosity falls above or below a predefined threshold, the photocell switch circuit activates or deactivates the lighting system, whichever is the case.
Advantages of Using the Photocell Switch
Having understood the above functioning and application of a photocell switch, you will know that this simple circuit provides you some infallible advantages:
- Low circuit energy cost
- Affordable adjusting system
- Automation can be molded in any desired time format and interval
- Works in complex light designs
- Can work according to the intensity of the available light
- Can work in terms of adjusted time
- A simple circuit that can be easily linked to any lighting system
Thus, a photocell switch is a very simple circuit that is efficient enough to provide you a very flexible degree of lighting automation and switch lighting safety guidelines that can provide you the required ease in operating any lighting system or structure.