Datasheet of 2N It is apparently a visible light phototransistor (also includes IR since no IR filter is indicated) –no wavelength is indicated. PHOTOTRANSISTOR. Part Number: WP3DP3BT. Features. ○ Mechanically and spectrally matched to the infrared emitting. LED lamp. ○ Blue transparent lens. The circuit you show should work as it is, since it is already for a phototransistor. Just leave your base lead floating. EDIT – the breadboard.
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Phototransistor Circuit Configurations | Applications | Electronics Notes
How can I design a circuit which utilizes a photo-transistor to make a light sensitive switch that is when there is no light in room, the led connected to the photo-transistor lights up and when there is light in room, the led connected to Phototransistor turns off? In reality the phototransistor does not give a particularly linear output to the input stimulus and it is for this reason that this mode of operation is more correctly termed the active mode.
However as the level of light increases, current starts to flow. These are very rough approximations, but show the order of magnitude of the various values and comparisons. The reason the circuit is usually not the best way to do this is because it relies upon Hfe, which can vary quite widely in a transistor and is subject to temperature changes. So if you are intending to eventually power this circuit from phitotransistor else other than a coin cell, then you should go for the common emitter circuit Steven describes.
Phototransistor circuit configurations The phototransistor can be used in a variety of different circuit configurations. Like more conventional transistors, the phototransistor can be used in common emitter and common collector circuits. The collector of an n-p-n transistor is made positive with respect to the emitter or negative for a p-n-p transistor.
The collector is taken to the supply voltage via a collector load resistor, and the phototraansistor is taken from the collector connection on the phototransistor.
High values of base resistor R b prevent low levels of light from raising the current levels in the collector emitter circuit and in this way ensuring a more reliable digital output. The choice of common emitter or common collector phototransistor circuit configuration depends upon the requirements for the circuit. Transistor Q1 will want to increase that fold to get mA collector current. The common collector, or emitter follower phototransistor circuit configuration has effectively the same topology as the normal common emitter transistor circuit – the emitter is taken to ground via a load resistor, and the output for the circuit being taken from the emitter connection of the device.
In order to ensure the optimum conversion and hence sensitivity, the emitter contact is often offset within the phototransistor structure. Please tell me if this is correct. Broadcast technology Embedded Design principles Distribution Formulae. We are a franchised distributor of electronic components, as well as a sourcing and procurement agent for hard-to-find, obsolete, and allocated parts.
Any schematic or circuit diagram would be really helpful. Umer – I added a schematic and edited the text. Nowadays, distributors provide a very effective service, meeting the many needs of development, manufacturing and service organisations small and large. You might have to experiment with the values a bit to get your required sensitivity, as mentioned above.
Umer Farooq 2 4 The phototransistor can be used in a variety of circuits and in a number of ways dependent upon the application. Phototransistor characteristics As already mentioned the photo transistor has a high level of gain resulting from the transistor action. The operation of the phototransistor circuit in the switch mode is more widely used in view of the non-linear response of the phototransistor to light.
What resources have you read phototransisgor app notes, etc. The phototranslstor actually acts as an amplifier.
In reality the phototransistor does not give a particularly linear output to the input stimulus and it is for this reason that this mode of operation is more correctly termed the active mode.
The site you got the above circuit from also has an example of such a circuit: The 1-Source Electronics group of companies provides a full suite of services to the electronics manufacturing industry.
You have absolutely no feedback in the circuit so that 30 mA may as well be mA, probably destroying the LED in a circuit with a higher power supply. The collector is taken to the supply voltage phototransisotr a collector load resistor, and the output is taken from the collector connection on the phototransistor.
Here phototranwistor the link but I am using photo-transistor but this circuit is for LDR, so how can I use photo-transistor in this circuit? Very early photo transistors were made by not covering the plastic encapsulation of the transistor with pphototransistor paint.
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Just leave your base lead floating. As a result of their ease of use and their applications, phototransistors are used in many applications. We will gladly help you locate any Electronic or Electrical Parts. Old OC71 transistor – by removing the black paint it exhibited phototransistor characteristics One of the drawbacks of the phototransistor is that is particularly slow and its high frequency response is very poor Phototransistor circuit symbol The phototransistor symbol consists of the basic transistor symbol with two arrows pointing towards the junction of the transistor.
High values of base resistor R b prevent low levels of light from raising the current levels in the collector emitter circuit and in this way ensuring a more reliable digital output.
The base of the photo transistor would only be used to bias the transistor so that additional collector current was flowing and this would mask any current flowing as a result of the photo-action.
Maybe change the resistor to 2k or larger if you are worried about blowing the LED. They are very similar to the characteristics of a conventional bipolar transistor, but with the different levels of base current replaced by the different levels of light intensity. Sorry Stevenvh never mind. Sign up or log in Sign up using Google. Steven – In general yes, but we’ll have to agree to disagree on this one I think: Supplier Directory For everything from distribution to test equipment, components and more, our directory covers it.
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The performance of the phototransistor can be superior to that of the photodiode for some applications in view of its gain. This is amplified by the current gain of the transistor in the normal way.
Power Transistors RF Transistor. The phototransistor phototarnsistor be used in a variety of different circuit configurations. You can leave the base floating unconnected or connect it to ground through a resistor. To help with the breadboard I just threw together the little circuit shown in your question. Like the photo-generated carriers this is also subject to the amplification by the transistor action.
Rc or Re in the diagrams above. Part of the learning can be finding out for himself why this circuit would be not ideal in most situations, and then trying it other ways.