How Accurate is My Solution for IC and VCE in a Silicon Transistor Circuit?

In summary, you are tasked with determining the IC and VCE of a silicon transistor with a B value of 100 and a VBE of 0.6V. Using Kirchoff's laws and the given circuit, you can calculate the required values to be IC = 1 mA and VCE = 18.04 V. It may be helpful to simplify the circuit by using a Thevenin equivalent for the base bias network.
  • #1
martyg314
6
0
This is for a 300 level electronics lab class and I'm wondering if I'm close:

Homework Statement



If the following silicon transistor (VBE = 0.6 V) has a [tex]B[/tex] value of 100, determine IC and VCE.

Homework Equations



http://img862.imageshack.us/img862/80/circuit1.th.jpg

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The Attempt at a Solution



First I found an expression for [tex]\alpha[/tex] (0.99) and noted that
VBC=VCE-0.6

Then I used Kirchoff's laws for the BE loop and the "loop" from the -15 V down to ground:

BE Loop:
-15 + 2000IC + VCE + 1000IE = 0
-15 + 2990IC + VCE = 0

15 V to Ground:
-15 + 40000IB +VBC + 2000IC = 0
-15.6 + 2400IC + VCE =0

I then solved these equations to get:
IC = 1 mA
VCE = 18.04 V

Any tips would be greatly appreciated.

Also, if anyone can recommend a good electronics text. Mine (Principles of Electronic Instrumentation by Diefenderfer) is filled with errors and is short on example problems.

Thanks,

MG

Homework Statement


Homework Equations


The Attempt at a Solution

 
Last edited by a moderator:
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  • #2
It might be profitable to replace the base bias network with a Thevenin equivalent. Then the only loop you need to concentrate on will be the one containing the base-emitter.

Emitter current should be IE = IB(β + 1). Then, knowing VBE = -0.6V, you should have everything required to solve for IB, thence IC.
 

FAQ: How Accurate is My Solution for IC and VCE in a Silicon Transistor Circuit?

How do transistors work in a circuit?

Transistors are semiconductor devices that act as switches or amplifiers in a circuit. They consist of three layers of doped material, typically silicon, which create two junctions. By applying a small current or voltage at the base junction, the transistor can control the larger current flowing between the other two junctions.

What is the purpose of a transistor in a circuit?

Transistors are used to amplify or switch electronic signals in a circuit. They are essential components in many electronic devices, such as computers, televisions, and radios. The ability of transistors to control the flow of current makes them indispensable in modern technology.

What is a common problem with transistor circuits?

One common problem with transistor circuits is thermal runaway. This occurs when the transistor heats up due to high current flow, which causes an increase in temperature and further increases the current. This can lead to the destruction of the transistor and other components in the circuit.

How can I troubleshoot a transistor circuit problem?

To troubleshoot a transistor circuit problem, you can use a multimeter to test the voltage and current at different points in the circuit. You can also check for loose connections, damaged components, or incorrect wiring. If all else fails, you may need to replace the transistor or seek professional help.

What are some important considerations when designing a transistor circuit?

When designing a transistor circuit, it is crucial to consider the voltage and current ratings of the transistor, as well as the power dissipation and thermal characteristics. You should also consider the type of transistor (e.g., NPN or PNP) and its function in the circuit (e.g., amplifier or switch). It is also essential to follow proper circuit design techniques, including using appropriate resistors and capacitors to ensure stable operation.

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