Phototransistor Vs Light Dependent Resistor

March 16, 2017

Unlike the photocell the two phototransistor pins have polarity. Photo diodes and photo transistors are true semiconductor devices which use light to control the flow of electrons and holes across pn junctions while light dependent resistors are passive components lacking a pn junction.

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Hello everyone i want to be able to measure low light levels very quickly and i was wondering which would be better a phototransistor or a photoresistor.

Phototransistor vs light dependent resistor. A phototransistor supplies light level controlled current to a series resistor and the voltage drop across the resistor is measured using an ad so it is very similar to the earlier photocell hookup. As the name implies a light dependent resistor is a semiconductor device that changes its electrical resistance depending on the presence of light. The light dependent resistor ldr is one of the most widely used and preferred photo resistor in most projects that requires the use of a photosensor.

The light dependent resistor cell the most commonly used photoresistive light sensor is the orp12 cadmium sulphide photoconductive cell. Electronic symbol the symbol for a photoresistor a photoresistor acronymed ldr for light decreasing resistance or light dependent resistor or photo conductive cell is an active component that decreases resistance with respect to receiving luminosity light on the components sensitive surface. This light dependent resistor has a spectral response of about 610nm in the yellow to orange region of light.

The earlier demo program will also work for a phototransistor. This resistance is called as dark resistance. The most common type of photoconductive cell is a light dependent resistor or ldr.

The specific properties of each sensor are the main dictator of where and when they can be used. Light dependent resistors have a lower sensitivity than photo diodes and photo transistors. Phototransistors are transistors with the base terminal exposed.

When a light dependent resistor is kept in dark its resistance is very high. Photoresistor ldrs are light dependent devices whose resistance is decreased when light falls on them and that is increased in the dark. Phototransistors work in a similar way to photoresistors commonly known as ldr light dependent resistor but are able to produce both current and voltage while photoresistors are only capable of producing current due to change in resistance.

The most ideal characteristic it carries is that it is cheap and rugged. Hello everyone i want to be able to measure low light levels very quickly and i was wondering which would be better a phototransistor or a photoresistor.