Transistor Gain Calculation for Amplification: Requirements and Calculations

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Discussion Overview

The discussion revolves around calculating the minimum gain required for a transistor circuit to amplify a 2.5 mA signal to at least 0.1 A. Participants explore the implications of using multiple transistors in series, each with a specified gain, and how to determine the number of transistors needed based on the total gain required.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant calculates that the minimum gain should be 40,000 by dividing 0.1 A by 2.5 mA, but expresses uncertainty about this result.
  • Another participant questions how to achieve a gain of 40,000 by multiplying gains of 10 from multiple transistors.
  • Several participants clarify the conversion between milliamps and amps, noting that 1 A equals 1,000 mA and 0.1 A equals 100 mA.
  • One participant suggests that 5 transistors, each with a gain of 10, would be needed to achieve the required amplification.
  • There is a correction regarding the notation of current, with a participant noting that "ma" refers to milliamps, while "mu" refers to microamps, which leads to confusion in calculations.
  • A later reply indicates that a gain of 100,000 would also be acceptable based on the original problem statement.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the calculations and the correct interpretation of the problem. There is no consensus on the final answer, as different interpretations of the gain and current units lead to varying conclusions.

Contextual Notes

Participants highlight potential misunderstandings regarding the units of current (mA vs. μA) and the implications for gain calculations. There are unresolved questions about how to correctly achieve the required gain using the specified number of transistors.

felipenavarro
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Homework Statement



If a transistor circuit is used to amplify a 2.5 mA signal to at least
0.1 A, what must be the minimum gain of the transistor circuit?

b. Assume the amplifier consists of a number of transistors in series,
each with a gain of 10. How many transistors are needed in this circuit? (Hint: Two such transistors in series would provide a total gain
of 10 × 10 = 100.)


Homework Equations


gain current = output current/imput current


The Attempt at a Solution


for the first question i got that the current gain should be 40,000 by dividing .1 by 2.5*10^-6. i am not sure if this is correct, but if it is then how is it possible to get to 40,000 by multypling tens?(for question b)
 
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felipenavarro said:

Homework Statement



If a transistor circuit is used to amplify a 2.5 mA signal to at least
0.1 A, what must be the minimum gain of the transistor circuit?

b. Assume the amplifier consists of a number of transistors in series,
each with a gain of 10. How many transistors are needed in this circuit? (Hint: Two such transistors in series would provide a total gain
of 10 × 10 = 100.)


Homework Equations


gain current = output current/imput current


The Attempt at a Solution


for the first question i got that the current gain should be 40,000 by dividing .1 by 2.5*10^-6. i am not sure if this is correct, but if it is then how is it possible to get to 40,000 by multypling tens?(for question b)

How many ma are in an amp? How many in .1 amp?
 
well 1 million in an amp and 100,000 in .1 amps, so is this the answer for question b? that would be 5 transistors of ten in a row.
but don't i have to get the same answer (as a total amplification) as in question a?
 
felipenavarro said:
well 1 million in an amp and 100,000 in .1 amps, so is this the answer for question b? that would be 5 transistors of ten in a row.
but don't i have to get the same answer (as a total amplification) as in question a?

Ah, well now see ... THAT'S where your problem is the Greek letter mu is the symbol for micro. The "ma" means MILLIamp, not microamp.
 
oh! i don't know why it changed to ma the original problem uses mu i still need help with the problem! haha
 
but if it is then how is it possible to get to 40,000 by multypling tens

The question says

If a transistor circuit is used to amplify a 2.5 uA signal to at least 0.1 A

So a gain of 100,000 would also be acceptable.
 
ah! got to read with more attention! thanks !
 

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