Questions tagged [transistor]

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

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24 views

How to use one H-bridge to control multiple latching solenoid irrigation valves? [migrated]

I'm using Arduino Uno to operate a latching solenoid irrigation valve by using an H-Bridge to set the polarity of the 12V DC going to the valve. A 500 ms + pulse on a digital output pin turns the ...
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0answers
34 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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5answers
159 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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1answer
86 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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2answers
114 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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1answer
173 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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1answer
60 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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1answer
56 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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1answer
82 views

How to make a circuit to control a 24V solenoid

I'm new to programming with Arduino and a little rusty with circuitry. I'm trying to control a 24V solenoid with the Arduino mega board. I've done some research into this and I believe I have a code ...
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1answer
105 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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3answers
101 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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0answers
146 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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1answer
56 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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2answers
118 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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1answer
86 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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2answers
57 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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1answer
271 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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1answer
279 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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1answer
105 views

H bridge with transistors and an Arduino [closed]

I made an H bridge consisting of 2 PNP and 2 NPN transistors. See the schematic below. Here is the problem: When I set pin 9 on the Arduino HIGH and pin 8 LOW (now the upperright PNP and buttomleft ...
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1answer
51 views

H bridge with transistors not enough power [closed]

I am making an autonomous car from an old RC car. For the steering I made my own H-bridge, consisting of 2 PNP and 2 NPN transistors. When I connect everything, the motor works fine. But it hasn't got ...
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1answer
245 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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0answers
72 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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1answer
83 views

Which transistor I should use to switch 12V 0.8A? [closed]

I am have circuit with Arduino NANO and I need to control air valve, which is powered with 12 Volts and 0.8 Amper. Problem is that Arduino NANO is powered with 5 volts. I want to use transistor to ...
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1answer
211 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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1answer
2k 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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1answer
118 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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2answers
544 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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3answers
270 views

How many transistors can be connected to Arduino pins?

How many TIP122 transistors can I connect to the Arduino digital pins? The Atmega328p datasheet states that the pins can source a total of 200 mA, while other documents state 40 mA per pin. In the ...
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1answer
188 views

Confusion over Transistors for a switching circuit with an Arduino Mega 2560

Apologies if this is a stupid question asked by a noob, but I've looked around to try and find the answer and just can't work it out. Basically, I'm making a project on thingiverse (Glitch's MK2 ...
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1answer
2k views

Arduino Uno: Driving a small LED strip with 2N3904 NPN

I'd like to know why I cannot dim the small LED strip with my design. I can only turn them on and off. This is a problem for me as I wanted to have a fade effect. Here is my circuit: The voltage from ...
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2answers
983 views

Fast switching of high load using an IGBT [closed]

I want to control a high load with fast switching times (motorbike ignition coil) using an arduino. I found an IGBT that claims to be purpose built for that use case (ISL9V3040P3). This IGBT has an ...
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1answer
303 views

MCU to switch single coil latching relay not working (attempting array with common gnd)

I have several single coil latching relays, (EC2-5SNU). I am trying to control them by an MCU; connected directly they work fine, but I am iffy about keeping it this way so I'm trying to power them ...
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0answers
172 views

Motor on transistor causes arduino to reset

I have a motor hooked up to the emitter of a NTE24 transistor and ground, the collector is hooked up to 3.7V, and the base is connected through a 10ohm resistor to a PWM pin on an arduino mega, which ...
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3answers
3k views

How to detect if LED is switched on in external circuit using Arduino NANO?

I want to detect when an LED is powered on using an Arduino NANO. The LED is part of an external circuit. The LED uses about 1.8V. Would the circuit below allow me to detect when the LED is switched ...
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2answers
411 views

How can I connect nearly 450 LEDs to an arduino without drawing too much current?

The question seems simple, but there's more to it: I'm connecting 4 74HC595 shift-registers to an arduino pro micro. 28 of the 32 outputs will be used to control LED segments of numbers. Each segment ...
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2answers
2k views

Powering a DC motor with an external battery

I'm working on a project where i need to control a 6 volt motor with an Arduino. The motor that I'm using requires 6 volts so I'm using a 9 volt with a voltage divider to get those 6 volts. My problem ...
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1answer
1k views

Control a 5 volt water pump with an Arduino

I want to control (only on/off) a small water pump (5 V, 200 mA max.) with my Arduino. I read something about NPN transistor, because the output pins of the Arduino can't supply enough ...
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4answers
7k views

Transistor amplifier to drive speaker using Arduino PWM [closed]

I have been working on a project lately which uses Arduino to play a wav file from SD card. I am using TMRPCM library which made the job very easy. But the problem is that the output sound in the ...
2
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1answer
196 views

reverse 12v motor

I am working on an RC car, and I need to be able to reverse a 12v circuit that powers my main drive motor. I have a TIP102 transistor and a 5-30v relay for each motor terminal. I assumed that I could ...
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2answers
8k views

Using a transistor to get 100mA on a IR led

What i saw is that the led use 1.3V on 100mA with a 1:10 Cycle (100ms). Im currently at 30mA using only a 100 resistor, but the range of the led is 20cm at max, i want to get at least 2 meters. Since ...
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1answer
447 views

Cutting off OneWire/SDA line with transistors

I am developing a pcb for a design I am working on and I need to share a pin to be used by a ds18b20 (onewire) and some possible I2C sensors. There would be just one of each at a time. I was thinking ...
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1answer
663 views

Using an esp8266, how can I create a circuit to measure 2 different analog inputs (not simultaneously) with only one ADC pin available (A0)

I'm currently using a circuit with 2 separate transistors that can be switched on or off to measure 2 separate voltage inputs. The reason for this is because I'm using an esp8266 which has only one ...
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1answer
2k views

Why is my circuit working only when I touch it?

I have connected digital pin 2 of arduino to the circuit as shown: The problem is that the LED is not turning on normally its only turning on when I touch anything on collector side of circuit. What ...
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2answers
352 views

Autolock transistor for powering Arduino

I have a portable project where I want to take care about batteries getting discharged. Usually I just put a switch at the very beginning of my circuit that completely cuts off the electricity when ...
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2answers
184 views

Why is D3 not activating?

So I made this circuit + a momentary push button on D2 and GND: Because I don't use a real arduino, I use the RAW port to act like the +5V port. It all worked with a single LED without the npn ...
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2answers
934 views

Newbie Arduino DC motor problem

So I am new to Arduino and new to electronics in general. I've looked up a few tutorials and they all have a simple early tutorial that turns on a DC motor and turns it off again. Something like this: ...
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1answer
239 views

How can I switch a 1.5V buzzer with my Arduino?

I want to make my alarm clock “smart”. I'm very new to this stuff, that is, the hardware side. The programming shouldn't present too many problems. I’m currently experimenting with a simulator (http:/...
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2answers
207 views

Do I need a transistor if my relay has an optocoupler? [closed]

I'm looking to use this relay with my arduino. It has an optocoupler and correct me if I'm wrong but this should prevent any back EMF from affecting my arduino. Do I still need to use a transistor?
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2answers
318 views

Microcontroller software shutdown with transistor 2N4401

I am trying to understand why connecting, say, an Arduino digital pin 4 to a 2N4401 pin 2 as well as 5V PSU to 2N4401 pin 1 and Arduino VCC to 2N4401 pin 3, won't keep power. When shorting pin 1 and ...
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1answer
973 views

How do I control multiple LEDs strips with Arduino

I want to decorate my house with LEDs strips on each step of my stairs. I will buy LEDs strips with a 12V power supply. I want that if I put my foot on the first step, the first LEDs strip turn on, ...