Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [transistor]

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

0
votes
0answers
25 views

trigger capacitive touch using transistors [on hold]

I was wondering how to simulate a press on a smartphone. I know it is possible using relays or servos but I don't have relay nor enough place for the servos. Is it possible to do it using transistors?...
1
vote
1answer
57 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 ...
-1
votes
0answers
8 views

Don't know which transistor I should use [migrated]

I am new to transistors. I want to know which transistor I should use which will suffice for my H bridge. My motor draws 1.2A at 6V when stalled.
1
vote
3answers
53 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 ...
0
votes
0answers
50 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 ...
3
votes
4answers
6k 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 ...
-1
votes
1answer
47 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....
0
votes
2answers
83 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 ...
0
votes
2answers
385 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 ...
3
votes
2answers
295 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 ...
1
vote
1answer
47 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 ...
0
votes
2answers
48 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 ...
0
votes
2answers
289 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 ...
4
votes
1answer
199 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 ...
0
votes
1answer
88 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 ...
-1
votes
1answer
57 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 ...
0
votes
1answer
130 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 ...
-1
votes
1answer
47 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 ...
1
vote
1answer
89 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 ...
1
vote
0answers
63 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 ...
0
votes
1answer
68 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 ...
0
votes
1answer
119 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 ...
-1
votes
0answers
116 views

Arduino 24v I/O Shield

I'm searching an arduino uno shield that will allow to communicate with industrial grade PLC and sensors (24v). Something like https://github.com/TheDIYGuy999/Mega_PLC/tree/master/Digital_Input_Board ...
0
votes
1answer
791 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 ...
1
vote
3answers
182 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 ...
1
vote
1answer
145 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 ...
0
votes
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 ...
0
votes
2answers
679 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 ...
4
votes
3answers
2k views

Controlling a DC motor with an external power source

I'm trying to use an Arduino to release a single drop of water using a solenoid valve.  This article describes how to create this circuit with a Raspberry Pi using a DC powered solenoid that opens and ...
0
votes
1answer
243 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 ...
1
vote
0answers
156 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 ...
0
votes
2answers
1k 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 ...
1
vote
3answers
2k 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 ...
0
votes
1answer
333 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 ...
1
vote
1answer
568 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 ...
1
vote
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 ...
3
votes
7answers
20k views

How to eliminate noise from PWM controlled 12V fan at low speed

I am trying to build a simple fan controller (single fan). So far I have successfully created a circuit which powers the fan with an external 12v DC adapter and added a transistor (NPN) to switch it ...
2
votes
1answer
162 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 ...
6
votes
2answers
7k 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 ...
0
votes
1answer
816 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, ...
1
vote
1answer
1k 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 ...
3
votes
2answers
251 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 ...
1
vote
2answers
137 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 ...
3
votes
2answers
776 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: ...
2
votes
1answer
202 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:/...
-1
votes
2answers
173 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?
1
vote
1answer
57 views

Will a transistor always reduce the voltage? [closed]

I have an NPN transistor that's connected over a 12V adapter. I have tried using a potentiometer to change the resistance of the incomming current. Even if i take the resistance down to 0, I end up ...
5
votes
2answers
716 views

7 Segment display dimming

I've got project that needed to have some (4) digits display, and had plenty of 7 seg. displays lying around. I didn't have any multiplexers left but have instead wired it up as per this diagram: I'...
4
votes
1answer
238 views

Why is my transistor always transmitting?

I want to use a transistor to turn on and of an electric magnet, I have hooked up a transistor like this: simulate this circuit – Schematic created using CircuitLab The blue wire goes to the ...
0
votes
3answers
2k views

How to ground a arduino with an external power-source? [closed]

I have magnet hooked up to my arduino with a Darlington Transistor, like this: The powersource is a 12V adapter I'm pretty new to electronics but i'm told that the transistor won't work unless the ...