1. cikalekli

    Thevenin's theorem BJT derivation

    Here, I want to use Thevenin with those 2 resistors in the base. How can I combine those two resistors with thevenin or do you have any other better idea to combine them? (circled with red in the picture) (PS: I don't ask the solution of the question. I'm only asking individually the...
  2. cikalekli

    Input and Output Impedance of the Common Emitter Amplifier

    Hi, I just have solved one of the bjt common emitter question below. However, I'm curious that how can I additionally find those things below: 1) Input and Output Impedance 2) AC Gain Here is the example and my hand draw solution. However, the question only asked to find Vout/Vin... Also, my...
  3. M

    Calculating dc gain of transistor

    I looked at the data sheet for tip110. According to 1 graph. The gain depends on temperature. It was a graph of collector current vs DC current gain. I saw three lines, 1 for 25 Celsius, 1 for -55 Celsius, 1 for 125 Celsius. What if the temperature is 10 Celsius, how do I calculate the gain?
  4. T

    How do I not pass current with 0V input? is it possible to change the input voltage range?

    Hello everybody! I have two questions. I have this circuit where I want to vary the input voltage (V1) between 0V and 5V to supply power to R2. Is it possible to make the circuit not supply a power (0W) to resistor R2 when my voltage V1 is 0V? When I do the simulation with 0V in V1 there is...
  5. M

    Controlling high power LED with transistor and Arduino

    Hello, I'm doing a small project and I'm stuck. I want to control brightness of 90v 185mA LED strip with my Arduino Uno. I used bd941 transistor in series with LED strip and I'm sending signal form arduino PWM digital pin to 100om resistor and then to transistor base.(in datasheets for...
  6. A

    Type 807 Tube RF amplifier with transistor a pre amp

    Hi all, I have a 807 vacuum tube and I want to make a CW RF amplifier with it. I am thinking of using transistors in pre amplifier and 807 as final power amp. I have only one tube so I cannot make push pull amp. First of all I need to know if it will be possible to make such RF amplifier. If...
  7. Selvedin

    How to make a flashing switch from a Transistor

    Hello guys, I need to make a circuit in which a transistor acts like a flashing switch. I watched some videos but the Problem is that I don't have the exact same components as in the Video shown and so my project fails. Can you help me? Kind regards to all good people
  8. Z

    Problem with transistor

    Hello, in the following image you can see a circuit with a npn transistor. I marked the given values with red and the unknown with blue. Below the circuit you can see my calculations and solutions. I'm stuck at finding I1. I would be very thankful for some guidance.
  9. J

    Having problems trying to get a high side switch to work 3V switching on 5V

    The context of my project is I am using an ESP-01 as a "smaller" circuit that is deep-sleep capable, running off a coin cell. It turns on a larger MCU with its own battery pack and runs at a higher voltage. Both work together regarding data transmission. The first time I made this thing, it was...
  10. V

    what is the smd equivalent package of BD139 NPN transistor?

    I am developing a basic switching circuit using a PIC microcontroller where the maximum drive current will be up to 2A in this case I was using BD139 but now due to my PCB has a Single-layer option I have to use SMD for it. so, please anyone suggest to me the best NPN SMD transistor for my...
  11. C

    Transistor is just not working

    Hello everybody, I have a small question about transistors. I have a npn transistor (bc337). I have 5Volts on the emitter from an arduino. The base goes to a resistor (1k) and then to ground. The collector goes to a resistor (330) and then through a LED to ground. As far as I understood the...
  12. C

    How to identify burned transistor?

    CPU Dell vostro 3668 motherboard i5 7th gen How to identify the burned transistor... 4496 is shown... Other half is missing .... Images are attached...
  13. noname1234

    Searching Transistor which transforms 3.3v to 12v (level shifting problem)

    Hello there, I am trying to control my ws2811 led strip with my raspberry pi 4. But unfortunately the strip requires 12v and the gpio pins of the raspberry pi can only provide 3.3v. Thats why I am looking for a transistor that can take 12v (I have a 12v powersupply) and switch it on and off...
  14. P

    LED status readback circuit

    Sorry for such foolish question, but what is the behaviour of circuit below: LED_ON is 3.3V logic control signal, LED_STATUS is output signal to MCU pin (GPIO). When LED_ON is logic high and Q1 is open LED1 is ON and LED_STATUS = '0', but what will happen when LED_ON = '0'? Q2 will be...
  15. GastonJam

    Transistor as an amplifier

    I'm currently working on this circuit and I run upon this question which I'm not sure I understood it correctly : For starters I have these values below - UCE=5V R1=6.1kΩ R2=1.35kΩ RE=1kΩ R3=1.5kΩ V1=15V IC=2mA UBE=0.4V B=180 Given formula rBE≈40mV / IB First I calculated CE with the use...
  16. J

    IRF540N application as a switch trouble

    I am fairly new to using MOSFET's in circuits and I am a little stuck. I want to use the IRF540N as a switch, which will receive a voltage to the gate, and 18-30 volts at the drain. I would like for the source to essentially follow the voltage of the drain as long as there is voltage being...
  17. babaliaris

    I made my first amplifier!

    We kinda learned about this circuit in the electronics 1 lab, but I don't understand everything, i have some questions and unfortunatly my lab professor is quite a Karen and won't even hear my questions... Anyway, these are my questions: 1) Which elements can I mess with to increase the volume...
  18. E

    manage 12V pulse and 5V pulse on the same pin

    I have Atmel controller which requires a 12V pulse and 5V pulse during flashing. I have a 12V supply and derived 5V from it using a regulator. But I want to know how can I give the 12V pulse and 5V pulse on the same pin. We can manage to give pulse single voltage level using NPN transistor but...
  19. M

    How Did This Circuit Go So Wrong?

    I built this circuit based on the examples in the datasheet. It worked. Transistor Q3_1 is BUJ100LR,412Bipolar Transistors - BJT Bipolar Transistors - BJT Trans GP BJT NPN 400V 1A 3-Pin https://www.mouser.ie/datasheet/2/848/BUJ100LR-1846655.pdf C2_1 is 4.7uF Tantalum Capacitors 20V...
  20. Andrew Rudd

    wiring an arducam with the power line on a transistor

    I've set up an arducam mini 2MP plus with a nrf52DK (similar to an arduino for this set up) to take pictures. Ive got the board and camera working when the camera is wired with the VCC line and GND wired directly into the boards 3.3v line and ground pins. The arducam uses about 100 mAmps when...
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