NPN transistor is always flickering and on

In summary, the speaker is new to hobby electronics and has assembled a circuit to control a power LED over wifi using esp8266. However, the LED is always on and sometimes flickers regardless of what is sent through GPIO1 port. The problem is believed to be with the NPN TIP41C transistor, and the speaker is advised to check the wiring and pinout of the transistor. If the LED does not turn off when pins 1 and 3 of the transistor are shorted, then the transistor may need to be replaced. The speaker is also advised to check the ESP8266 GPIO pin for a pull-down and to consider using a 4.7k resistor between pins 1 and 3 of the transistor.
  • #1
doggy
2
1
TL;DR Summary
DIY circuit problem with NPN transistor.
I'm completely new in hobby electronics, and I assembled the following circuit to control a power LED over wifi using esp8266. The problem is, that it is always, on and sometimes flicker , no matter,what I send via GPIO1 port. I know that this is not an esp8266 problem, I tested my program with a simple low power LED, without the NPN TIP41C transistor. I'm sure, I do something wrong with connecting that transistor. What should i do?
 

Attachments

  • PcVSf.png
    PcVSf.png
    6.6 KB · Views: 344
Physics news on Phys.org
  • #2
  1. Check that you have the TIP41C wired correctly, the pinout is slightly different than many. See the datasheet you linked to.
  2. Temporarily short TIP4C pin 1 to pin 3. With the power ON the LED should be Off.
    2a) If it stays On, check your wiring.
    2b) If still On AND wiring is good, replace TIP41C
  3. If LED goes Off with pins 1 & 3 shorted:
    3a) Verify that the ESP8266 GPIO pin is programmed/configured with a pull-down.
  4. If all the above are correct, connect a 4.7k resistor between pin 1 & pin 3 of the TIP41C.

Some voltage measurements will likely be needed for further troubleshooting. I hope you have a voltmeter.

Note: There are several variations of the ESP8266 as shown by the characters after the 8266. Some have a programmable pulldown and others a programmable pullup on the GPIO pins. This MAY be a contributing factor to your problem.

Have Fun! (and let us know what you find)
Tom
 
  • Like
Likes doggy, berkeman and DaveE
  • #3


Hi there! It sounds like you may have wired the transistor incorrectly. Make sure that you have the correct pinout for the TIP41C and that you have connected it to the correct GPIO pin on the esp8266. Also, double check your circuit to make sure that all connections are secure and that there are no loose wires. If the problem persists, you may want to consult a schematic or ask for help from a more experienced hobby electronics enthusiast. Best of luck!
 

Related to NPN transistor is always flickering and on

1. Why is my NPN transistor always flickering and on?

The flickering and constant on state of an NPN transistor is usually caused by a faulty or damaged transistor. This can happen due to overheating, overloading, or incorrect wiring. It is important to check the specifications and proper usage of the transistor to prevent this issue.

2. Can I fix the flickering of my NPN transistor?

In some cases, the flickering of an NPN transistor can be fixed by replacing the faulty transistor with a new one. However, if the issue is caused by incorrect wiring or overloading, it is important to address those issues first before attempting to replace the transistor.

3. Is it normal for an NPN transistor to flicker?

No, it is not normal for an NPN transistor to flicker. Transistors are designed to switch between on and off states, not to flicker. If your NPN transistor is flickering, it is likely due to a problem with the transistor itself or its usage.

4. How can I prevent my NPN transistor from flickering?

To prevent your NPN transistor from flickering, make sure to use it within its specified parameters and avoid overloading it. It is also important to properly wire the transistor and ensure that it is not overheating. If the flickering persists, it may be necessary to replace the transistor.

5. Can a flickering NPN transistor damage my circuit?

Yes, a flickering NPN transistor can potentially damage your circuit. The flickering can cause inconsistent power flow and may lead to overheating, which can damage other components in the circuit. It is important to address the flickering issue as soon as possible to prevent any further damage.

Similar threads

Replies
11
Views
2K
Replies
2
Views
1K
Replies
16
Views
4K
  • Electrical Engineering
Replies
11
Views
2K
Replies
10
Views
1K
Replies
68
Views
4K
  • Electrical Engineering
Replies
19
Views
1K
  • DIY Projects
2
Replies
50
Views
6K
Replies
80
Views
3K
Replies
5
Views
2K
Back
Top