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Questions tagged [transistor]

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

9
votes
2answers
15k views

When should I use a transistor, mosfet, and when should I use a relay? [closed]

I am used to relays some, and they are useful, especially for large loads like a incandescent light bulb or other 120V AC device. However, it seems like overkill to use a relay for a bunch of LEDs ...
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 ...
5
votes
2answers
720 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
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 ...
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 ...
4
votes
1answer
5k views

How to switch an external circuit with Arduino?

I have an object with a series of led and I want to turn on and off these leds from my Arduino. The input of the LED circuit is 24v DC 100mA. What I've done is the following: I've cut a wire of this ...
4
votes
1answer
239 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 ...
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 ...
3
votes
2answers
783 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: ...
3
votes
2answers
298 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 ...
3
votes
2answers
254 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 ...
3
votes
1answer
3k views

Using 5V arduino with 12v solenoid lock

I wish to use an arduino like this with a 12v solenoid lock like this. How can I do this. I am told that using this might work, but I am also thinking I can use a transistor's amlification to do that. ...
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
2answers
351 views

How is the diode here effective?

I'm working on project 9 of the arduino starter-kit - the motorized pinwheel. Here is the schematic: The diode in question (and the only one here) is toward the bottom right of the breadboard. It is ...
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:/...
2
votes
2answers
228 views

Bizarre transistor behavior and voltage with DC motor in simple circuit

I started a new motor related project recently with a new Arduino Uno, beginning with several tutorial circuits included in the Vilros Arduino guide. The circuit in question is #10, a simple DC motor ...
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 ...
2
votes
1answer
2k views

Use transistor to press button on external device

I have a small device with a simple push button. I'd like my Arduino to be able to make the device register button pushes. It seems like the best way to do this is to use a transistor to close the ...
1
vote
2answers
216 views

How come my transistor doesn't work?

I have a TIP 120 to 229 NON 60V 5A transistor I'm trying to use it to switch an electro magnet. Using the blink example to test it out: // the setup function runs once when you press reset or power ...
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 ...
1
vote
4answers
3k views

Arduino Driver can I use only PNP?

is it possible to use a normal PNP transistor to drive a motor? I'm kinda new to this stuff so I want to be on the safe side, so I don't damage my Arduino Uno because of the motor. I have made a ...
1
vote
2answers
7k views

Controlling an LED using a transistor (TL188)

I wanted to control an LED using a transistor (my first attempt at using a transistor). I connected a transistor (TL188) to pin 13 of an Arduino Uno accidentally and noticed something. (The resistor ...
1
vote
2answers
526 views

Fog machine Arduino integration

I want to control my fog machine with an Arduino. Has a simple button that is used to activate the machine. I want to press this button using an Arduino digital output pin, but the fog machine is ...
1
vote
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 ...
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 ...
1
vote
1answer
146 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 ...
1
vote
1answer
736 views

DC motor kickback diode?

I have the following circuit: And I know it works and that the diode protects the negative voltage from flowing back into the transistor. This is essentially the circuit: Could someone illustrate ...
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 ...
1
vote
1answer
48 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 ...
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
3answers
184 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
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
2answers
139 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 ...
1
vote
1answer
932 views

Use MOSFET to Change Voltage With PWM

Ok so forgive me for being an amateur but I'm having a situation that's driving me nuts. I have a sensor that I have to cycle between +5VDC and +1.4VDC every 60 seconds. I'm using an ATTiny85 with ...
1
vote
1answer
980 views

Four Fast PWM outputs, in parallel

I need four Fast PWM signals for four different transistors. I want to use timers 1+2 (pins 3, 11, 9, 10) so it wouldn't interfere with delay(...). I tried setting the timers to Fast PWM mode, and ...
1
vote
1answer
1k views

Dimming 6W (24V DC 0.25A) LEDs using Arduino

I want to dim 24 LEDs which are powered by a transformer outputting 24V 6W at 0.25A I am worried about temperatures, especially considering the circuit has to stay on for several hours keeping the ...
1
vote
1answer
2k views

How do I use a 3 legged phototransistor?

I have searched the Internet and found the following circuit to use with my phototransistor but it is not working, I can say so because all analog input i get is 1023 even if i have covered it totally,...
1
vote
1answer
1k views

DC Motor not behaving reliably

Using an Arduino Mega. I have a motor hooked up exactly like the picture below. Using a BC548B transistor, 1N4001 diode, 220 ohm resistor and a 9V battery. I'm driving the motor in code by using PWM ...
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
vote
0answers
64 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 ...
1
vote
0answers
157 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 ...
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 ...
0
votes
2answers
49 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
902 views

Tv remote connection to an Arduino

I have a tv remote that I want to connect to an Arduino so that I can send a series of commands to the TV using the remote. I would like to open the remote and solder transistors or a Transistor ...
0
votes
1answer
90 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 ...
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 ...
0
votes
2answers
458 views

Switch 230V 50Hz using a digital out pin

I would like to control normal household appliances like lamps, pumps etc. using my Arduino with up to 5 A. I looked a little around, but it seems, that most relais draw more current than the Arduino ...
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 ...
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
1answer
53 views

Regarding the output voltage and current in arduino

This is basically an off-shoot from https://arduino.stackexchange.com/questions/20569/unexpected-output-pin-behavior-was-relay-on-off-doesnt-loop. It's the same schematics and so on, however, I'm now ...