What is the principle of phototransistor?
The working principle of a phototransistor is similar to a photodiode including an amplifying transistor. The light falls on the base terminal of a phototransistor then it will induce a little current then the current amplified through the action of a normal transistor, which results in an extensively large.
What is a phototransistor and how does it work?
The phototransistor is a semiconductor device that is able to sense light levels and alter the current flowing between emitter and collector according to the level of light it receives.
What is the characteristics of a phototransistor?
Characteristics of Phototransistor As phototransistors are basically Bipolar NPN Transistors with large base – collector junction, the characteristics of a Phototransistor are similar to that of a simple BJT. Phototransistors are available as two-leaded or three-leaded devices.
Which of the following are the disadvantages of phototransistors?
Disadvantages of phototransistors include:
- The material used may limit voltage handling capability (silicon cannot handle over 1,000 Volts)
- Electrons do not move as freely as they do in electron tubes.
- Vulnerable to electrical surges and electromagnetic energy.
Where are phototransistors used?
The phototransistor is widely used in electronics devices likes smoke detectors, infrared receiver, CD players, lasers etc. for sensing light. They also find applications in Opto-isolators, Position sensing, Security systems, Coin counters, etc.
What is difference between Photodiode and phototransistor?
Photodiodes pass less current compared to phototransistor while in photodiode consumes less current than a phototransistor. The dark current of the phototransistor is much higher than a photodiode. Photodiode produces both voltage and current while phototransistor generates only for current.
What are phototransistors used for?
Phototransistors are used extensively to detect light pulses and convert them into digital electrical signals. These are operated by light rather than electric current. Providing a large amount of gain, low cost and these phototransistors might be used in numerous applications.
What is meant by phototransistor?
phototransistor. / (ˌfəʊtəʊtrænˈzɪstə) / noun. a junction transistor, whose base signal is generated by illumination of the base. The emitter current, and hence collector current, increases with the intensity of the light.
What is sensitivity of a phototransistor?
The SFH 310 has a viewing angle of up to about 25 degrees off the central axis, and it is sensitive to light of wavelengths 450 nm to 1100 nm, which includes much of the visible spectrum (about 390 nm to 700 nm). Peak sensitivity of the SFH 310 is at 880 nm.
What are advantages and disadvantages of phototransistors?
➨Phototransistor is more responsive to light than photoresistor. ➨Phototransistors are cheaper. ➨Phototransistors can produce a voltage which can be used in conjunction with microcontroller housing ADC. ➨Output current of phototransistor is easily obtainable.
How do IR phototransistors work?
A phototransistor works just like a normal transistor, where the base current is multiplied to give the collector current, except that in a phototransistor, the base current is controlled by the amount of visible or infrared light where the device only needs 2 pins.
What is the purpose of a phototransistor circuit?
Phototransistors are used extensively to detect light pulses and convert them into digital electrical signals. These are operated by light rather than electric current. Providing a large amount of gain, low cost and these phototransistors might be used in numerous applications.
What happens when there is no light falling on a phototransistor?
When there is no light falling on the phototransistor, a small amount of leakage current known as Dark Current flows from collector to emitter. When there is enough light falling on the base terminal, a base current is produced, which is proportional to the intensity of the light.
Can a base terminal be used as a phototransistor?
From the above curve, it is clear that as the intensity of the light increases, the collector current also increases. As mentioned earlier, phototransistors are also available as three-terminal devices. In this case, the usage of Base terminal is optional. When used, it acts as a regular BJT and when not used, it acts as a Phototransistor.
Which is an example of solid state phototransistor?
Photovoltaic and Photoconductive devices like Photodiodes, Photoresistors (also known as Light Dependent Resistors or LDRs), Phototransistors etc. are example of solid-state i.e. semiconductor Light Sensors of quantum detectors type. What is a Phototransistor?