Solve Transistor Trouble: Physics Help

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In summary, the conversation discusses a question about a transistor circuit and the attempts made to solve it. The question itself is deemed to be faulty and the attempts at solving it involve labeling the transistor, explaining why the bulb only lights briefly when the switch is opened, and ways to increase or decrease the time delay and prevent the bulb from lighting up. The conversation ends with the suggestion to adjust the resistor value to prevent the bulb from lighting.
  • #1
Eline1.618
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I need some guidance on this question, and possibly a check over my attempts? I'm not exactly a star Physics student. Help is much appreciated.

Homework Statement


[PLAIN]http://img835.imageshack.us/img835/8124/ques.jpg [Broken]

6) Label the above transistor.
7) If switch S is opened, the bulb only lights up for a moment. Explain why this happens.
8) How to increase the time delay?
9) Explain how to make the bulb not to light up.
10) Explain how to change the time delay.

Homework Equations


None of which I am sure of...

The Attempt at a Solution


Before we begin, the whole question seems a bit... uh, screwed up. But maybe I'm wrong. Here's what I did:

6) NPN (assuming that the emitter is connect to common point, not at bulb)

7) False statement. When capacitor (C) charges up, transistor turns on. Bulb is lit, and stays lit. The said delay, is between when the switch is opened and the bulb is first turned of.

8) Increase the value of C.

9) Remove battery? It sounds like a cheap answer. Any better ones?

10) ...

I also made a different attempt afterward:

6) PNP

7) During the time C is charging there is a current through, and therefore a voltage across, R. This turns on the transistor until the voltage drops.

8) R and/or C should be increased.

9) Remove battery? Sigh.

10) Should be similar as question 8; R and/or C value is decreased or increased.This may be a trick question to begin with, because my teacher seemed pretty confident that none of us in the class would be able to answer.
 
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  • #2
Eline1.618 said:
I need some guidance on this question, and possibly a check over my attempts? I'm not exactly a star Physics student. Help is much appreciated.

Homework Statement


[PLAIN]http://img835.imageshack.us/img835/8124/ques.jpg [Broken]

6) Label the above transistor.
7) If switch S is opened, the bulb only lights up for a moment. Explain why this happens.
8) How to increase the time delay?
9) Explain how to make the bulb not to light up.
10) Explain how to change the time delay.

Homework Equations


None of which I am sure of...


The Attempt at a Solution


Before we begin, the whole question seems a bit... uh, screwed up. But maybe I'm wrong. Here's what I did:

6) NPN (assuming that the emitter is connect to common point, not at bulb)

7) False statement. When capacitor (C) charges up, transistor turns on. Bulb is lit, and stays lit. The said delay, is between when the switch is opened and the bulb is first turned of.

8) Increase the value of C.

9) Remove battery? It sounds like a cheap answer. Any better ones?

10) ...

I also made a different attempt afterward:

6) PNP

7) During the time C is charging there is a current through, and therefore a voltage across, R. This turns on the transistor until the voltage drops.

8) R and/or C should be increased.

9) Remove battery? Sigh.

10) Should be similar as question 8; R and/or C value is decreased or increased.


This may be a trick question to begin with, because my teacher seemed pretty confident that none of us in the class would be able to answer.

I think your answers are fine. I agree that the question is wrong -- with neither the NPN nor PNP topology will the bulb just light briefly at switch opening.

BTW, to keep the bulb from lighting in the NPN case, you can do something with the value of the resistor that keeps the bulb current very small (too small to light it) -- what can you do with the R value?
 
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1. What is a transistor?

A transistor is a semiconductor device that is used to amplify and switch electronic signals. It is an essential component in modern electronics and can be found in a wide range of devices, from computers to smartphones to televisions.

2. What are the common problems associated with transistors?

The two most common problems associated with transistors are overheating and failure to switch. Overheating can occur due to excessive power or poor cooling, and can cause damage to the transistor. Failure to switch can be caused by a damaged or malfunctioning transistor, or incorrect circuit connections.

3. How can I troubleshoot transistor problems?

To troubleshoot transistor problems, you can use a multimeter to test the transistor for proper functioning. You can also check the circuit connections and make sure they are correct. If the transistor is overheating, you may need to adjust the power supply or add additional cooling.

4. What are some tips for solving transistor trouble?

Some tips for solving transistor trouble include checking for any physical damage or loose connections, making sure the transistor is properly grounded, and using the correct voltage and current ratings. It is also important to use transistors that are compatible with the specific circuit and application.

5. Can I replace a faulty transistor myself?

Replacing a faulty transistor can be done by someone with knowledge and experience in electronics. It requires careful handling and soldering skills. If you are unsure or uncomfortable with replacing the transistor yourself, it is best to seek professional help from a qualified technician.

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