Solving Transistor KFY34 Switching Load Homework

Thread starter -SJ-
Start date Jun 21, 2014
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Switch Transistor

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SUMMARY

The discussion focuses on solving a homework problem involving the KFY34 NPN transistor, which is required to switch a load with a nominal supply voltage of 24V and a resistance of 60Ω. Key calculations include determining the base current (Ib) necessary to ensure the transistor operates in saturation, with the current gain (h21E) specified between 35 and 125. The participants clarify that the voltage across the transistor in cutoff mode is 24V and in saturation mode is approximately 0.6-0.7V. Additionally, they emphasize the importance of designing for the worst-case scenario regarding beta (β) to ensure reliable operation.

PREREQUISITES

Understanding of transistor operation, specifically NPN transistors.
Familiarity with the concept of current gain (h21E) and its variability.
Knowledge of basic electrical circuit principles, including Ohm's Law.
Ability to read and interpret transistor datasheets.

NEXT STEPS

Study the KFY34 transistor datasheet to understand its specifications and characteristics.
Learn how to calculate base current (Ib) using the formula Ib = Ic/β.
Explore the concept of transistor saturation and cutoff states in detail.
Research methods for plotting current and voltage as functions of time in transistor circuits.

USEFUL FOR

Electrical engineering students, hobbyists working with transistors, and anyone involved in designing or analyzing switching circuits using BJTs (Bipolar Junction Transistors).

Jul 2, 2014

-SJ-

That Uce should be typical. The KFY34 transistor has Pmax=800mW, so 440mW should be fine and no additional cooling is necessary.
OK, that's it. I'll send it to my examiner to check it out and be with hopes he will accept it despite the terrible time spent at solution.

I would like to say THANK YOU REALLY VERY VERY MUCH for patient guidance in this long-suffering thread. Now, I am hopefully a bit wiser about calculations with transistor and looking forward to learn more.
Thank You.