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Does LED glow in reverse bias?
An LED is a light emitting diode. The LED emits light when it is forward biased and it emits no light when it is reverse biased. The intensity of light is proportional to the square of the current flowing through the device.
Which diode is used in IR sensor?
Active IR Sensor In most of the applications, the light-emitting diode is used as a source. LED is used as a non-imaging infrared sensor whereas the laser diode is used as an imaging infrared sensor. These sensors work through energy radiation, received & detected through radiation.
How do IR diodes work?
An IR LED (infrared light emitting diode) is a solid state lighting (SSL) device that emits light in the infrared range of the electromagnetic radiation spectrum. Used with infrared cameras, IR LEDs can act like a spot light while remaining invisible to the naked eye.
Can You reverse bias the base emitter of a BJT transistor?
If the 15V supply comes up before, or stays up after, the 12V supply, the reverse bias will be 15V, and the emitter-base junction will break down for all but a few types of transistor. What are the consequences of such breakdown? If the current is limited, as in your case to no more than 1.5mA, not much.
How does a reverse biased diode work in reverse?
A PNP transistor works the same way but in reverse. From a first approximation, the depletion zone of a reverse-biased diode is simply an insulating region. But this doesn’t explain the collector junction of a transistor. We need to look at this insulation-effect in more detail.
Is it safe to reverse bias a be junction?
The BE junction can be reverse biased, and your PNP will be off. The limit is the BE-junction breakdown voltage, as for any PN junction. As long as you don’t exceed that breakdown voltage, you’ll be safe. The maximum reverse voltage the BE junction can withstand is usually listed in the datasheet in the Absolute Maximum Ratings section.
What does a reverse biased NPN transistor look like?
Anyhow, this is what an NPN transistor looks like: so as you say, the collector-base junction is reverse biased and no current flows. Although it isn’t clear from the picture, the base is very thin and lightly doped so the hole density is quite low.