Determining Part Number for NPN Transistors

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    Npn Transistors
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Discussion Overview

The discussion revolves around identifying suitable part numbers for NPN transistors for a specific circuit application. Participants explore various transistor options and address circuit design issues related to the use of these components.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant requests assistance in determining the part number for four NPN transistors, indicating a lack of prior discussion on this topic in their course.
  • Another participant suggests several suitable NPN transistor types, including BC547, 2N2222, and others, while noting that they may have different pinouts.
  • Concerns are raised about circuit diagrams being incorrectly drawn, specifically mentioning short circuits at the terminals.
  • A suggestion is made to use pull-down resistors to better define input signal states in the circuit.
  • A participant inquires whether a KN2222 transistor can be used as a substitute for the 2N2222, questioning their equivalence.
  • In response, another participant advises comparing datasheets to determine compatibility between the KN2222 and 2N2222 transistors.

Areas of Agreement / Disagreement

Participants express differing views on the circuit design and the suitability of specific transistor models. There is no consensus on the correctness of the circuit diagrams or the equivalence of the KN2222 and 2N2222 transistors.

Contextual Notes

Participants highlight potential issues with circuit design, such as short circuits and the need for pull-down resistors, but do not resolve these issues or clarify the implications of using different transistor models.

Who May Find This Useful

This discussion may be of interest to electronics students, hobbyists working with NPN transistors, and individuals troubleshooting circuit designs.

chemic_23
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hello good day, would someone kindly help me determine the part number of these 4 npn transistors here? pls help, cause my prof didn't discuss this yet.. and i don't have idea on how to calculate for the values of the transistor to determine tha part number suitable for the circuit... many thanks (um this isn't homework by the way)


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Hello, I take it you understand that the transistors are NPN>

Pretty well any small or medium signal NPN transistor will do here, they do not even have to be of the same type.

Common Suitable types might be

BC547/548/549
2N2222(A)
2N3704
2N3904
MPSA42/43
2SC1318

Remember these have different pinouts or connection arrangements so make sure you know the one for the transistor you actually use.
 
circuits drawn wrongly, in both 0v & +6v terminals are shorted on left side. in 1st circuit lamp terminals are shorted?
 
aks786 said:
circuits drawn wrongly, in both 0v & +6v terminals are shorted on left side. in 1st circuit lamp terminals are shorted?

Yes good catch.
 
You should detach the 'Earthy' end of those lines and use 1k 'pull down' resistors after the switches if you want to really define the states of the input signals.
 
o, i see, sorry I've overlooked that.. thanks.. um, btw, can i use KN2222 transistor instead of 2N2222? are they the same?
 
chemic_23 said:
o, i see, sorry I've overlooked that.. thanks.. um, btw, can i use KN2222 transistor instead of 2N2222? are they the same?

You should compare their datasheets. That's what we would do.
 

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