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Questions tagged [transistor]

A semiconductor component used for amplifying or switching electrical signals. Use this tag for discussing transistor circuits.

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1 answer
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Problems in running two solenoid together at the same time

I am trying to activate two solenoids (12V/350mA, connected to a 12V/1A adaptor) at the same time using the TIP120 NPN-transistor and 1kohm resistor using the UNO board. Using a simple program, void ...
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4 votes
2 answers
546 views

Controlling a 5V fan and ultrasonic fogger with an arduino - do I need an external power supply?

I know the whole controlling a fan with an arduino thing is getting old, but somehow I still don't get it to work. Tried to answer it based on other questions but I am too much of a newbie to ...
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0 votes
1 answer
187 views

arduino 28BYJ-48 stepper only whining, not rotating

Edit, this question has been answered in the comments by chrisl, and also after retesting the code with delay() which showed I forgot to update my lastupdate variable(eerst), I have answered it in the ...
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0 votes
2 answers
113 views

Switching fan on with transistor, fan running very slowly

I want to control a fan with an arduino from 0 rpm to full rpm. Using a (modified) pwm signal from the arduino I can control the speed w/ the pwm signal, but it cannot go all the way to 0 rpm. So I ...
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1 vote
0 answers
56 views

PID cooler temperature control

Hello Hello I am making a controller of a small cooler (dry ice) PID but Im not sure if I am using the indicated mosfet Im trying with a NPN 222a and my second option is IRFZ44 Which would be the best ...
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1 vote
3 answers
146 views

Why are transistors necessary before LEDs?

Below is the small RGB LED circuit I'm trying to build. My question is why are the 3 transistors necessary, and can I not link the LEDs directly?
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3 votes
2 answers
63 views

connecting a small motor to arduino using a transistor

I want to connect a small motor (water pump) to an arduino, and I am not sure about the circuit. The pump is small, works with 3.3V, but consumes 0.1A so I decided to use a transistor. The one I have ...
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0 votes
1 answer
97 views

Motor not switching with 2N3904

I have a small motor, it powers fine from the 3V3 and GND output of the arduino nano ble 33. However I need to be able to switch it on and off. My first attempt was to use an output pin, but that ...
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  • 131
0 votes
1 answer
63 views

Switching 4.2V circuit with 3.3V Arduino GPIO

I am trying to learn about MOSFETs and see this p channel MOSFET and this tutorial. I am trying to use a 3.3V arduino GPIO pin to control a load that is powered from a 4.2V battery in much the same ...
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  • 170
0 votes
1 answer
41 views

Is it possible to use the same power source for the arduino and a high current

I've need to control some leds which draw 300mA with an arduino (actually an atmega) and after some searching I think the following is the circuit I need, but I'm not really sure if the power source ...
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1 vote
1 answer
98 views

Arduino H-bridge for rc car

I've got an old rc car laying around, of which i would like to swap the insides, but re-use some of the parts that are already in there. The car runs 2 dc motors: one for steering, one for throttle. ...
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1 vote
0 answers
73 views

Motor not working when using Nano 33 BLE and transistor because of low voltage

I'm a beginner using a new Arduino Nano 33 BLE to power a low voltage motor. I've tested that the motor can run using a standard 1.5V AA battery when connected directly, but I cannot get it to work ...
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0 votes
1 answer
52 views

How can a DC motor (toy) be run with only an Arduino and transistor without an external power source?

I'm trying to understand this circuit found here. I understand that the Arduino cannot directly run a DC motor because it can only supply 40mA of current and also due to the back EMF which can damage ...
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0 votes
2 answers
120 views

How to use a push button & transistor as a kickstarter for power supply?

My goal is to save energy, and I intend to do so by powering a chip with itself, and cut power whenever unnecessary. The best image I can have is of a startled monkey who jumps on the branch, screams ...
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  • 167
0 votes
1 answer
78 views

Variable Fan Controller - Properly Sized Transistor

I would like to a build a temperature sensing variable speed fan controller for my truck. Currently using a purchased 2 speed on/off relay based controller, but my fans are overloading the whole ...
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  • 119
3 votes
1 answer
638 views

Why is it i need transistors and resistors to turn a dc motor with an Arduino but i can connect it directly to a battery

As the question says im building a circuit to run a DC motor whenever motion is detected on a motion sensor. Now as this image suggests I need a diode + resistor + transistor to get this thing to ...
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0 votes
2 answers
852 views

DC motor fan speed control with Temperature Sensor [duplicate]

I used this circuit schematic for the project however, when DC Motor starts to work, temperature value is increasing abnormally high. How can I solve this problem? It shows abnormal high values like ...
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  • 9
2 votes
1 answer
43 views

Why won't my motor run?

I am trying to run a small 3v motor with a Keyestudio MEGA 2560(which is the same as the Arduino MEGA 2560). I am getting a consistent 5 volts everywhere I check with a multimeter. The voltage drops ...
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  • 31
1 vote
1 answer
81 views

Unreliable function of transistor, pump and ESP32

I have a 12 VDC pump, 8.5A, connected to a MOSFET transistor PSMN5R6-100PS,127. The connection from the transistor to transformer, pump and a ESP32: 1 Gate --> port to ESP32 2 Drain --> ...
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  • 111
1 vote
0 answers
32 views

How can I power off a servo the best way? Problems with MG90S servo [duplicate]

I have a NodeMCU and im trying to control a servo to move from angle A to B and viceversa. The thing is I want to be able to power off the servo after moving so it could stop getting voltage and ...
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  • 111
1 vote
2 answers
596 views

Read encoder output by using an optocoupler

I have a 512 pulses encoder with four wires: +5V, ChannelA, ChannelB, GND and I'm using it as feedback for my motor position (max 80 RPM) on Arduino UNO. Everything works fine, but I need also to ...
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1 vote
2 answers
196 views

Why does controlling power with a transistor interfere with MHZ19B's serial communication?

I've been trying to turn off an MHZ19B (datasheet and teardown photos: revspace.nl/MH-Z19B). I've used an Arduino, NPN, PNP transistors and mosfets as well as the diagram below for connecting the ...
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-2 votes
1 answer
367 views

BJT - BC547 not working with LED strip

I'm connecting an LED strip that takes 12V input to an Arduino Uno R3's 5V VCC using a B547 transistor. Here's my circuit: Base -> 1K ohm resistor -> DO13 Collector -> -ve of LED strip ...
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  • 99
5 votes
1 answer
624 views

Switching a Solenoid Using Arduino's 5V Output?

I'm a bit stumped on how to switch on a solenoid using a transistor using my Arduino Nano's 5v Output. The solenoid runs on 12V, so I used an NPN transistor to connect the 12V source to the solenoid ...
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  • 205
0 votes
1 answer
98 views

Relay + Arduino uses too much power for battery to handle. Which solution is best?

You can see in my crumby schematic that I am using a Non-latching relay to turn on a 3A circuit (one of them arc lighters), which is powered by a 25C (supposedly) lipo battery. That same battery also ...
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2 votes
2 answers
288 views

Arduino 5V pump digital pin

I am trying to control a 5V pump with arduino and ultrasonic sensor however i can't make it work with the pump connected to a pin. I saw on the forum that you need transistor or relay but i don't ...
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1 vote
2 answers
540 views

Arduino MKR 10100 control DC Motor

Thank you for reading my post. I have been stuck on this for several weeks now! I am trying to turn ON/OFF a DC motor from Arduino IOT Cloud. I have set up the cloud and added the switch. Everything ...
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  • 111
0 votes
1 answer
336 views

24v LED strip with common anode?

I have a 5m strip of 24v tunable white LEDs and I'm trying to figure out what I need set it up. There's a pad for V+ and then one for brightness and one for warmth. If I plug the V+ in V+ on a 24v ...
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  • 103
1 vote
0 answers
51 views

Control 12V power with 3 transitors to 3 seperate consumers

I have this shematic. With one electrical Pump and two solenoid valves I want to control via the arduino. Here are the specs for the parts: Pump: 12V max. 250mA Valve 1: 12V max. 160mA Valve 2: ...
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  • 121
1 vote
5 answers
1k views

Why does the transistor burn out

I have an arduino uno which turns on a water pump (12V, 3.6W) once every 10 hours for a few minutes (I've followed this tutorial on how to connect the water pump). To turn on the water pump I used a ...
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-1 votes
1 answer
2k views

Using an NPN transistor as a switch to turn on/off a DC Motor

I am trying to control a 3V DC motor (FA-130) with my Arduino Uno, and am trying to do that using an NPN transistor (2N3904) as a switch, as shown in this diagram. I used the Blink example and ...
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1 vote
2 answers
737 views

How can I use a transistor to "press" a button?

I have a heater remote that I want to press the buttons of with my Arduino. I am powering both the remote and Arduino from an external 5V source so both grounds are connected. Currently I have tried ...
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3 votes
1 answer
2k views

LED not blinking when using a transistor

I want to control an led using a transistor. The led gets it‘s power from an external 5v dc power supply. For the transistor I use an 1kΩ base resistor. The transistor is a BC547C (npn). The ...
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0 votes
1 answer
474 views

Can you drive a stepper motor without the L293D

Can you drive a stepper motor without L293D. Don't awnser without giving explanations or saying it will be cheaper to buy the L293D. Thanks
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0 votes
1 answer
279 views

Controlling a 5m LED strip with a Nano or Uno

I'm wanting to control a 12V LED strip (5m, 60 LEDs per meter) with a Nano or Uno. I know from Adafruit that I'll need some power transistors but I'm not sure that I have the right type. I have 6 ...
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  • 188
1 vote
1 answer
185 views

Water tank false trigger

I am trying to make a simple water overflow protection system for my home. I have created it using BC547 and NodeMCU (ESP8266). I have a simple circuit like this: The problem here is I have 2 wires ...
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1 vote
3 answers
262 views

Arduino Uno with 6x 5V solenoids + 9V battery - Not enough power?

I have 6 5V solenoids connected to an Arduino Uno, each of them with a TIP120 transistor, diode and resistor. Exactly like https://core-electronics.com.au/tutorials/solenoid-control-with-arduino.html ...
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  • 111
0 votes
0 answers
860 views

Arduino LED PWM dimmer starts blinking on low PWM values

I'm trying to build a PWM led dimmer with Arduino using this circuit: simulate this circuit – Schematic created using CircuitLab Everything works fine until the pin PWM 3 drops below the ...
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  • 101
-1 votes
1 answer
398 views

12 V relay using Arduino [closed]

I want to control a 12 V relay using an Arduino 5 V signal, but due to some unknown reason the relay does not work. I am using a BC548 transistor as a switch for relay. Please suggest where I go wrong....
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0 votes
2 answers
259 views

How is this simple transistor circuit suppose to work? [closed]

I've tried to replicate this circuit today. My motor is a computerfan, they apperntly don't need a flyback diode since there are no brushes. I used a 12V power source for my arduino and hooked it up ...
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  • 191
1 vote
1 answer
238 views

Sanity check for dual IR LED circuit [closed]

If the intent is to drive the two LED's with 200-400mA (using PWM @ 38Hz), is there anything wrong with this solution? Perhaps this is a better solution, as it ensures the current is exactly the same ...
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0 votes
2 answers
255 views

Vary voltage using relay. Is this possible?

I am planning to control a RGB lamp using Arduino. The lamp is 24V and I want to be able to control the brightness of the lamp. I found a relay that will let me control the 3 channels (red green and ...
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3 votes
1 answer
599 views

What's the function of this transistor on Arduino Mega?

I am trying to get information about the transistor on the Arduino Mega board below: It says "340P" on the transistor. I want be able to know which model transition is this so that I can check its ...
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1 vote
1 answer
2k views

Solenoid "vibrates" instead of pushing

I'm using my Arduino Uno to control a 5V 1A solenoid. I'm using an N-Channel MOSFET linked to the Uno's 0 pin to switch the solenoid on and off. It is protected by a Schottky diode. Initially, I ...
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  • 13
0 votes
1 answer
510 views

Making an H-bridge with transistors [closed]

I am trying to make an H-bridge with two NPN and two PNP transistors to drive a motor which works fine on the 5 V Arduino. I have a schematic in the picture. When I use a simple code to have pin 9 ...
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  • 19
2 votes
0 answers
82 views

Do I need one N3904 for each LED?

I want to control 4 (or more) LEDs using the PWM output pins of my Arduino. Here is how I have it on a breadboard, and it's working for me. Question: Is this schematic inefficient? Are there any ...
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0 votes
1 answer
634 views

Transistor as switch for signal and high current buzzer [closed]

I'm a newbie in transistor switching. I have PIR sensors with C and NC onboard. NC is 12 V signal that I need to switch transistor (bipolar?) to emit 3.3 V (collector connected to 3.3 ...
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0 votes
2 answers
4k views

Dim a led using a NPN transistor

I know there are a lot of questions about this topic, but I've tried everything and any possible guide online without success. I want dim (increase and decrease the brightness) some leds (3.5 Watt ...
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  • 103
2 votes
1 answer
264 views

Arduino + Solenoid Lock

I was trying to use a solenoid lock alongside the arduino, using a 12V 2A DC adapter, TIP120, and a diode. The circuit looks something like this. However, the lock isn't going in automatically (it ...
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  • 123
0 votes
2 answers
1k views

Controlling multiple fans using arduino uno

I'm kind of new on the field of Arduino. Although I have a question concerning multiple fan connection on 1 arduino PWM pin. The goal is to connect around 8 to 16 fans on 1 arduino pwm header pin and ...
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