Questions tagged [resistor]

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

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1k views

Preforming impedance termination for UART Communication (TX and RX) pins

I need two Arduino devices (Arduino Mega and Nano) to communicate with each other via UART. The two Arduino devices are long distance apart from each other. The distance is 1.5 meters. The Arduino 1 ...
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87 views

Powering arduino sensors - what resistor should I use?

Recently I have asked a question, why my sensors do not work on external power supply (link). I have found out, that I was limiting the current too much with the resistors. I have tried using two ...
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Multiple I2C BREAKOUTS with pull-up resistors doesn't work [UPDATE]

[UPDATE] Now it works fine but the as soon as I add the GY-521 module (hardware not software), it starts sending me crapy info Project uses: Arduino Pro Mini as brain FTDI as a programmer GY-521 ...
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45 views

Generate number

I wanna make some sketch to generate number to represent sensor value, with range from high (900) to low (670), that number decrease with range between 1-10 and with some delay of switching number ...
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61 views

Do all pins of Arduino Uno output 5V?

I am currently working on a project which uses PIR motion sensor and 5V relay. Since you might be familiar that both the motion sensor and the relay requires a 5V connection. My problem is, I don't ...
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3answers
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Multiple I2C slave devices on Arduino - Pull-up values

This question is asked a lot and I've found many usable details on different forums regarding adding pull-up resistors on SDA/SCL lines. I know that only one resistor should be added on these lines ...
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1answer
47 views

Does blinking an LED with no resistor for a few seconds harm my Arduino?

I am new to Arduino and I just made my first LED blink. I connected the LED to ground and digital pin 13 without resistance (for only a few seconds). Does this harm my Arduino? Hilmi
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1answer
511 views

4-20 milliamp to volts to pressure maths

I am measuring pressure in bars from OsiSense™ XMLP pressure sensor (4-20 milliamp) on a arduino uno. When the machine im measuring pressure on is switched off the reading is 0v as expected. When the ...
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322 views

How do I pull up D1-D6 using 10k ohm resistors?

I'm using push buttons to control CR servos (button1=turn CW; button2=turn CCW). How do I pull up D1-D6 and what does that do exactly? I can't find a tutorial that explains it well enough how to use ...
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3answers
133 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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134 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 ...
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2answers
7k 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
236 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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1answer
35 views

ISR Issue: Arduino Pro Micro

I'm trying to do a small test where I am using the ISR on the Arduino Pro Micro it up from sleep mode. I'm using a Force Sense Resistor (FSR, a resistor that changes it's resistance depending on how ...
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1answer
83 views

Is this circuit properly made?

I can't get to work a circuit that doesn't look that hard to copy. This circuit was done for an Arduino extension of my DSC HS2032 system. I was trying the example "Status" on the Arduino's ...
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2answers
4k views

Minimum value I2C-pull up resistor for arduino

I'm trying to determine the minimum value of pull resistor for Arduino Uno The datasheets says for arduino; VOL = 0,4 for IOL = 20 mA. (VDD = 5V) For formula for calculation of minimal pull-up is: ...
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1answer
92 views

Coding force sensitive resistor to give output based on time used?

I have a basic set up of having a force sensitive resistor being used to power an LED as can be seen below. I am wondering how I can code it so that the LED is lit after a pressure has been applied to ...
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1answer
632 views

In a circuit with a switch and a pull-down resistor, why does the high impedance of the input not discourage current from flowing into pin?

I'm a beginner to Arduino and circuits. I've spent the last couple hours hung up on the concept of how current flows through switches and pull-down resistors, having read every thread and watched ...
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1answer
44 views

Arduino Starter Kit - firmly wiring longer parts

I am getting started with project 01 on the Arduino starter kit. I'm facing an issue when wiring parts with long ends e.g. led & resistor. To make the simple circuit with led, resistor & ...
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1answer
65 views

Switch between ntc resistor sensors time based for other device

We have a heating system that uses an ntc resistor to measure water temperature. I would like to replace that ntc resistor by a fixed one (low enough to disable heating) temporary on a 5 minute ...
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1answer
49 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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1answer
586 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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1answer
111 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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23 views

0.96 oled i2c display not working with my Arduino Nano [duplicate]

So what I've tried is: Changing the i2c address from 0x3D to 0x3C and it still doesn't work. Ive also tried an i2c scanner and it hasn't worked either. First I connected the screen like this: GND-...
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2answers
82 views

How do I know if I need to use a resistor in a circuit?

I have been trying to find answers on Google to this question but cannot seem to find any answers that actually pertain to what I am wanting to know. I would consider myself a beginner in the area of ...
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0answers
38 views

Button example: resistor vs wire

I am playing with this basic example: Arduino: Button There're a lot of existing questions about why to connect button to the ground. I get the idea more or less. Is done to avoid "noise" during ...
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2answers
235 views

multiple RC522 RFID on arduino yun

I was trying for one month to make multiple RC522 rfid readers work together on SPI on an arduino yun, one works fine, but if I plug 4, each with a specific slave select, only one, sometimes 2, ...
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0answers
42 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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1answer
139 views

Menus not changing when button is pressed TFT 128 x 128

I've just followed a tutorial so that when a button is pressed it goes through a menu. Click once, next slide. Only issue is it isn't appearing on my screen at all. It has uploaded but I'm a total ...
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1answer
97 views

Connecting DAC output from Arduino Due to another arduino

I have an Arduino Due and I want to connect the output from the DAC as an input to an Arduino Uno's analog input pin. From this link http://forum.arduino.cc/index.php?topic=164763.0, user DuaneB ...
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2answers
43 views

Schematic interpretation, where to put resister?

I'm new to schematics, trying to figure out where to put a resistor (no instructions other than the schematic) I'm told I need: 10K variable Resistor x 1, 4.7K Resistor x 1, 100 Resistor x 1 But I ...
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1answer
30 views

Button isn't working properly

I am new in arduino trying to make race game. My problem is that my button (all buttons) is working sometimes and sometimes not. I am pretty sure that it's because of my code. Could you please help me ...
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1answer
43 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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0answers
43 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
471 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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1answer
130 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
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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1answer
179 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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2answers
50 views

Load Resistor Use for Voltage Sensing by Arduino

I connected a piezoelectric film to a Arduino Uno board via analog input. However, as I was getting very high voltage values (reaching 5 volts without much movement). Therefore, I added a 1 megaohm ...
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1answer
1k views

Pulse counter to measure flow-rate: 0 Pulse issues

I am using a Netafim M-Series flow meter interfaced with a UC-32 Arduino. The goal of this is to create a pulse counter than in turn will allow us to determine flow rate in the meter. (1 US gallon per ...
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1answer
501 views

Minimum value of a pull-down resistor

I've just started working with the Arduino UNO SMD edition and I'm also quiet new to electronics in general. Recently I wanted to try out this tutorial https://www.arduino.cc/en/Tutorial/Button and I ...
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1answer
1k views

Understanding schematics: resistors attached to Attiny85 pins V-USB

I'm currently trying to create my own Attiny85 usb thumb(to mimic an joystick). I understand that I have to limit the voltage on the attiny's pins that are connected to the D+/- pins from the usb. In ...
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1answer
208 views

What should the cut-off frequency be? [closed]

To convert a PWM signal to a DC voltage it must be filtered with a low pass filter. How can you know which cut-off frequency should be used and how do you calculate the values for the resistor and ...

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