Questions tagged [resistor]

Passive electronic component which reduces current flow in a circuit, dissipating power as heat.

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3answers
176 views

Why have resistor at end of circuit cycle if GND dissipates final energy?

The first challenge on the Arduino Uno manual is to make a closed circuit with a button and LED. The voltage is provided by the 5V pin (non IO), connected by wire to (+) on the bus (breadboard). The ...
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1answer
151 views

digitalPin giving lower voltage than Vcc

I am using an ATTINY88 for a project that requires to turn on an LED. Right now I am using pin PA1(ADC7/PCINT25). I noted, however, that when the pin is ON, I get about half the voltage that is ...
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1answer
45 views

How to encode resistance change (reed) for Arduino?

I have a water counter which switches reed on each 10 liters of water. I would like to count these values with Arduino. I wrote a program which counts changes from analog input and connected counter ...
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2answers
638 views

Use LDR with 220 ohm resistor

I have read many tutorials on LDR(Light dependent resistor) with Arduino which includes a 10 kilo ohm resistor but can i use it with 220 ohm resistor or even without resistor.
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3answers
119 views

How can I understand the circuit diagram for Arduino Starter Kit Project 4?

I have acquired the arduino starter kit project book, and the explanations seem at times confusing and difficult to understand. Concerning the above circuit diagram, the book states (I am ...
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1answer
41 views

How to 'label' module using electric techniques

I am in a project where it makes set of 'modules(set of separate circuits that will work as a sensor when connected to the board' that would be connected to Arduino Mega. Currently, I'm planning to ...
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1answer
160 views

Photoresistor Switch

How would I use a photoresistor like a switch. My issue is it is always bleeding out a little bit of power and always on. Is there a way to connect it to a digital pin and when a resistance of xxx is ...
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3answers
2k views

What is the minimum wattage of resistors for breadboarding with Arduino Uno?

I'd like to buy new resistors for breadboarding with my Arduino Uno. There are 0.25W, 0.4W, 0.6W, 1W, 2W, 3W, 5W, 10W resistors in the shop. What is the most suitable for this operation?
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1answer
128 views

Diode lights generate false interruptions

I have spent quite a considerable time debugging my code that was triggering false interruptions. I have found out that the source of the error were the diode lights (on the picture). I would like to ...
0
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1answer
499 views

Driving multiple LED arrays with shift registers

The project I'm building requires multiple LED arrays. I'm going to wire these LEDs in parallel and then connect the arrays to individual pins on a shift register. In addition to the LEDs running in ...
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3answers
1k views

does INPUT_PULLUP uses power?

When using a digital pin as input, one has the option of using the internal arduino resistor, which is connected to VCC; that is setting the digital pin as INPUT_PULLUP, and then the pin reads HIGH. ...
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2answers
7k views

10k ohm Potentiometer vs 10k ohm Resistor on LCD Display

I'm trying to use a LCD Display with my Arduino, but I don't have a potentiometer and all of the guides I find always require one, usually a 10k ohm potentiometer. The point is that I'm not very good ...
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1answer
501 views

what is the importance of the resistors that connect to push buttons ? can i replace them by wires?

Please, iam a junior in arduino and i want to know what is the importance of the resistors that connect to push buttons? can i replace them by wires? thanks in advance.
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2answers
6k views

Can I supply the board's 3.3V directly to the AREF pin?

Short dumb question: can I connect the 3.3V pin and the analog reference pin (AREF) directly? I've heard mentions of a 32K internal resistor but I'm not willing to risk a short circuit without ...
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1answer
106 views

Use of Resistor in PinWheel Exercise

I'm working on project 9 of the Arduino starter kit - the motorized pinwheel. Here is the schematic: (if img not showing: https://goo.gl/tqZmKD) My question is, why is the 10k resistor needed after ...
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2answers
3k views

Why all blink tutorials use 330 ohm resistor

When I do the led calculation I found 150 ohm resistor is enough for 3mm red led. If so why all arduino tutorials, like this one, are suggesting 330 ohm resistor? I assume V = 5 Volt, diode forward ...
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2answers
477 views

How to interface DS1801 digital resistor with Arduino DUE SPI interface? What clock rate so use?

I am trying to program a digital resistor and set it's wiper resistance. The general circuit looks a little like this where "pot" represents the Maxim DS1801 digital resistor and DUE is, of-course the ...
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0answers
39 views

Why is a resistor to GND needed for a switch that is open? [duplicate]

I don't understand the books explanation for why a 10k resistor is needed for an open switch to write LOW to a digital pin. I thought no voltage is LOW anyway. Can someone explain in a little more ...
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1answer
450 views

Lighting 5 leds…the last one lit is always dim

I have a simple project with a close deadline. I am trying to light up 5 LEDs as part of the project. The first 4 light up in sequence fine, and if I light up just the last one it lights up fine, but ...
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2answers
226 views

Source power with 2 V and LED with forward voltage of 2 V

I have a source power with 2 V and 100mA. I have an LED that has a forward voltage of 2 V and a max current of 20mA. Should I use a resistor to reduce the current? I see many formulas in the internet ...
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1answer
125 views

How much current and voltage has my resistor + LED

I have a very simple circuit: 5v -> LED (5mm, forward voltage of 2 V and max. current of 20mA) -> 1k ohm resistor -> GND. I want to know how much current is flowing in my circuit. I am using this ...
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1answer
179 views

how to calculate correct resistor value to use with LEDs Potentiometer and other devices?

I have been following http://arduino.cc/en/Tutorial/Fade to fade and LED. But I don't know why they are using a 220 Ohm resistor. According to Ohms law if LED is of 2.2 V and it runs on 0.025Amps and ...
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2answers
126 views

Which side should I connect the resistor on?

I understand that when connecting an LED and a resistor in series; the resistor can be placed on any side of the LED as the current will remain same in a series connection. Please correct me if I'm ...
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2answers
98 views

What does the datasheet information for a switch mean?

I'm clueless when it comes to the information on datasheets for switches. When I see a datasheet for LEDs or servos, I'm used to seeing a fairly straightforward call out for the required volts and ...
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2answers
1k views

Performance of internal vs external resistors

Is there any significant performance trade-off between buttons wired with the internal vs external pull-up/down resistors? I see a lot of tutorials demonstrating the use of external resistors when ...
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4answers
2k views

Importance of resistor

I'm new to Arduino and also new to electronics. I'm following the tutorial here. I'm not understanding the importance of the resistor in this schematic diagram. Can someone please help me on this?
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2answers
3k views

Can two LEDs attached to different pins share their resistor?

I'm designing an Arduino style board with built-in LEDs for several of the pins. To simplify assembly of the board and save on components, I was wondering whether it would be safe for those LEDs to ...
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1answer
4k views

Sensors and leds. This need resistors? and how?

I have a project with leds and sensors, this is my first project in Arduino and I want to know if it need resistors and how and where? I use 16-Bit I/O Expander MCP23017 for leds and multiplexer ...
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4answers
8k views

Can I change VCC pin to 3.3V on a 5V Arduino Pro Micro?

I'm using a 5V Arduino Pro Micro (schematic). For my project, I'm using the VCC pin to output power to an external device. I need VCC to output 3.3V to the external device. Can I open jumper SJ1 to ...
9
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3answers
2k views

Digital Read Serial tutorial - calculating the resistor value

The Arduino Digital Read Serial tutorial guides you through the wiring of a simple button. My questions are centered around the resistor. Why is the resistor necessary? I think I understand this, ...
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4answers
1k views

Setting a Pin to HIGH to simulate a button with a “pull up” resistor

in the below Fritzing diagram, I have a button that has a pull-up resistor, which when pressed, sets the GPIO Pin 23 to HIGH. On the Raspberry Pi, when the button is released, the GPIO goes LOW. The ...
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2answers
3k views

Use Higher Resistance Than Instructed in a Circuit

I'm following the "Get Started with Arduino" Guidebook, and I'm at the part where pulse width modulation (PWM) is discussed. The instructions say to create a simple circuit with a breadboard, red ...
23
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3answers
5k views

What happens to the Arduino if you don't use a resistor with an LED?

Making a blinking light seems to be one of the most common beginner projects with Arduino. A typical approach is to connect an LED + resistor (in series) to an IO pin, and connect the other end to ...