Questions tagged [arduino]
Be sure to use the Arduino Stack Exchange for questions that are more Arduino and less electronics.
866
questions
22
votes
1
answer
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How to properly use a relay module with JD-VCC from Arduino/Raspberry?
[EDIT]
A quick benefit of JD-VCC, is that allows you to control the relays that are 5V with 3.3V GPIOs. Check the full answer to understand why :)
[Original question]
I got two 4-relay-modules and I ...
- 1,256
24
votes
3
answers
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Measure Lithium ion battery voltage (thus remaining capacity)
What I am working with: I am running my self-made Arduino board (in the sense that I use the Arduino bootloader and code editor) at 3.3V, and powered from a Lithium ion battery, which is USB-charged ...
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90
votes
5
answers
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How much current can I draw from the Arduino's pins?
What's the maximum amount of current which I can draw from each of the Arduino's pins without tripping any of the internal fuses? Is there a limit per pin as well as an overall limit for the whole ...
- 1,937
46
votes
5
answers
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How can I use a 12 V input on a digital Arduino pin?
I am creating a controller for a 12 V system using an Arduino Uno microcrontroller. For the outputs I am using a relay shield to switch the 12 V components. I have a 12 V toggle switch that turns on ...
- 633
14
votes
4
answers
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Thermistor control of peltier voltage with Arduino (for DSLR chill box project)
I am mildly familiar with electronics, mostly from playing around with electronics kits as a kid. That was a long time ago, though, maybe as much as 20 years ago. I am currently working on a cold or "...
- 685
19
votes
2
answers
47k
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Input impedance of Arduino Uno analog pins?
I'm using the ACS712 hall-effect based current sensing chip on some small robotic arm motors, and reading in the analog voltage with an Arduino Uno. I've had reasonably good results, but only after ...
dustynrobots
12
votes
5
answers
6k
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"Overclocking" an AVR
In AVR datasheets under the Electrical Characteristics section you will typically find a graph like this (this one is from the ATMega328):
I've seen designs that seem to "work" but operate outside ...
- 22.9k
6
votes
3
answers
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Is it safe to use a voltage divider for Arduino and DC motor controller?
I have ordered a Dual H-Bridge 12A continuous (30A peak) Polulu motor driver shield for my upcoming (first time ever, a 1.2m long tank made of wood) robot project.
I was thinking about how to supply ...
- 381
12
votes
6
answers
38k
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Need help calculating resistance for transistor base
I have 3 12VDC/40A automotive relays (datasheet) that I want to use with my Arduino.
Based on the tutorial I am following (link) I need transistor, resistor, and diode. I am not an electrical engineer ...
- 443
57
votes
6
answers
140k
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Do I really need resistors when controlling LEDs with Arduino?
I'm just trying out Arduino Uno for the first time with 2 blinking LEDs on a breadboard. All the tutorials on the Internet seem to use a resistor. I do know the function of resistors, but does it ...
- 891
38
votes
2
answers
31k
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Selecting a MOSFET for driving load from logic
I'm looking to drive a magnetic door lock from an Arduino. I've found a question about driving a solenoid from an Arduino, which includes a circuit that looks perfect for this kind of situtation:
...
- 10.9k
38
votes
4
answers
11k
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I2C 3.3 to 5.0 V conversion
I'm trying to interface a 3.3V I2C device to a 5V Arduino.
I don't have any problem with SCL line.
I can use a simple voltage divider but I have an issue with the SDA line as this is bi-directional. ...
- 4,819
8
votes
4
answers
22k
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Detect car +12V using Arduino
I am looking to detect 12+V from a car wire using an Arduino.
I have found the following schematic:
I know how crazy automotive voltage can get so I just want to make sure the schematic I found ...
- 807
58
votes
7
answers
98k
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How can I get my atmega328 to run for a year on batteries?
Scenario
I have created a nice electronic door lock for my dorm room. It is currently an Arduino Diecimila with a servo [un]locking the door. It has a numerical keypad with 3x4 buttons and 5 LED's (2 ...
- 1,055
20
votes
8
answers
47k
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How many individual lights can an arduino control
I want to use a regular Arduino board to control LEDs - what is the most lights I can control individually from the board?
Is there a tutorial on how to hook it up?
- 5,070
12
votes
3
answers
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How do I get +5v for loud noise, 0v for silence from Electret Microphone (or other components)?
I have been asking a few questions here to get to a proper one, the initial questions I asked are linked to at the end. I used Fritzing to make up some schematics of my initial thoughts, but at the ...
- 1,181
4
votes
3
answers
6k
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High-side switch 24V 6mA control by Arduino
I would like to ask for best solution for my issue.
I need high side switch for 24VDC 6mA (it is enable signal for a device).
This device I want to control by Arduino (input 5 V 20mA).
What is the ...
- 63
68
votes
6
answers
273k
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What is the voltage range of a standard headphone jack from a phone?
I want to connect the output from the audio jack of an iPhone to an Arduino.
What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the ...
- 1,087
43
votes
2
answers
93k
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Purpose of the diode and capacitor in this motor circuit
I'm hooking up a small DC motor to an arduino using an NPN transistor using the following diagrams I found online:
The circuit works, and I'm successfully able to make the motor run. Now, I'm ...
- 807
12
votes
2
answers
38k
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Switching 9V using a NPN transistor and an Arduino
First of all, I'd like to say I'm not an Electrical engineer so please bear with me. I haven't got a sketch for what I'm trying to achieve but hopefully I can explain it ok.
I have an NPN transistor (...
- 394
10
votes
6
answers
5k
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Sensor for ultralow (to -85°C) freezer monitor
I am planning to build a series of Arduino-controlled temperature-reporting units for a room full of "Ultracold" -80°C freezers. (I ultimately want to convert the signal to a serial stream that will ...
- 201
4
votes
2
answers
2k
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Microcontroller soft off circuit not working - why?
I was making a board with an atmega328 mcu (to be used with Arduino libraries) to do some one wire communication stuff. Since I was etching the board anyway, I decided to try and implement a simple ...
- 513
3
votes
7
answers
16k
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Positive vs negative, power vs ground, flow direction
I'm getting very confused about the inconsistency where some people say ground is always negative, and some say ground is always positive.
And some would say, electrons travel from the power source to ...
- 131
41
votes
4
answers
5k
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What is "Arduino Optocoupler Disease"?
Another post on this site, when critiquing a pcb design, referred to "Arduino optocoupler disease" spreading across the internet. What type of design mistake does this refer to?
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votes
3
answers
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How do I create a permanent application from something prototyped with Arduino?
Part one of a three part series on transitioning from Arduino to a plain AVR microcontroller and minimum supporting components (part two, part three)
I've built up a project on my Arduino Uno to ...
Pete
11
votes
2
answers
27k
views
How to Use SFH235 IR Photodiode Correctly?
I have an SFH235 ir photo-diode (which datasheet can be found here) and only basic knowledge of electronics.
I want to connect the photodiode to an Arduino (the grand-plan is to add an ir diode and ...
- 287
7
votes
2
answers
8k
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Driving Solenoids from Arduino
I was wondering what the best way to run a solenoid would be from an Arduino board. I was thinking about using a MOSFET that runs into a relay to turn on the solenoid but am not sure how to go about ...
4
votes
1
answer
4k
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Arduino Negative Voltage Reading with Positive Ground
I am trying to measure voltage & current off a solar charge controller from panel, battery & load simultaneously with my arduino. I have managed to achieve this by tying all the negatives ...
- 45
0
votes
1
answer
2k
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multi channel ac dimmer for arduino
I have been looking for a simple ac dimmer circuit to use with my arduino and/or raspberry pi. I have used the TLC 5940 PWM Driver before just to control LEDs and I wanted to adapt this to controlling ...
18
votes
3
answers
106k
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Using a microphone with an Arduino
EDIT: I have been investigating in this problem for quite some time. It turns out to be a way more difficult project than I thought and not something for beginners. This requires expensive hardware (...
- 363
18
votes
6
answers
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How is binary converted to electrical signals?
I'm just starting off in electronics and am already fascinated. Having played with an Arduino these past few days I'm aware that binary is a representation of different voltages - such as +5V ...
- 281
14
votes
3
answers
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Read Positive and Negative Voltage in Arduino [closed]
It's a long story, but I took apart and RC car and wanted to have the Arduino use analogRead() to get the values of my motors and steering. I have measured with my ...
- 313
13
votes
1
answer
55k
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How to control a 12V solenoid valve with a mosfet?
I'm trying to control a 12V DC solenoid valve through a MOSFET (BS170), which receives its control signal (5V) from an Arduino microcontroller.
This is the basic schematic:
When I test the MOSFET, ...
- 443
11
votes
2
answers
28k
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Hooking up multiple RGB LEDs while using a minimal number of PWM pins on an Arduino?
I currently have an anode RGB connected to the 11, 10, & 9 PWM pins on my arduino. However I would like to add 3 more LED's to my project, but I don't want to necessarily take up every single PWM ...
- 191
11
votes
3
answers
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How would I get a full range voltage reading from a pressure sensor?
I am making an application using the DIY Force Sensitive Resistor (FSR) taken from this instructable. The resistance of this sensor typycally ranges from 20kOhm when at rest to 9kOhm when pressed.
...
- 2,301
11
votes
6
answers
26k
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Resistors in series with Tx and Rx
I'm making my own board and using an ATmega 328 with the Arduino bootloader. I have a DIP switch to select either an FTDI chip (for programming) to be connected to the ATMega's Rx and Tx, or a GPS ...
- 1,670
9
votes
4
answers
11k
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Triggering a capacitive sensor electronically?
I'm working on a little project I call my "Green Box". Basically, I'm trying to drop my electric usage as low as possible, without losing the convenience of my gadgetry.
So far, I'm incorporating a ...
- 231
8
votes
4
answers
3k
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How to remove noise in ADC voltage measurement?
I want to measure the open circuit voltage of a battery cell (differential reading, that is A0-A1). In order to do that, I am using an industrial PLC based in Arduino Mega and a cheap but accurate ADC ...
- 407
8
votes
2
answers
7k
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How do I connect a relay and transistor to an Arduino?
Ok, so this is what my relay looks like. I can't figure out what pins I hook the arduino and transistor to, and what pins to hook the the other device.
Please help.
ssfdr
8
votes
3
answers
3k
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Arduino Bootloader
I am very new to embedded world. I had been till now working only on S/W
Can anyone please explain me the use of the Arduino Bootloader? I want Arduino to perform some simple mathematics using some ...
- 295
8
votes
2
answers
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How do I get an Arduino (5 V) and MPR121 (3.3 V) to talk?
I have the Sparkfun MPR121 I2C Capacitive touch sensor breakout board
I have read that it uses 3.3 V, I know that I can't just connect up the 3.3 V power supply output from the Arduino as the ...
- 1,235
7
votes
3
answers
14k
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Replace BSS138 with AO3400A in level shifter circuit
I have to use level shifter circuit to interface MAX31855 with Arduino running on 5V.
I found easy to build level shifter circuit at SparkFun website. It is using BSS138 (datasheet) which I don't ...
- 303
7
votes
2
answers
7k
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Arduino Uno with 12V pump: transistor or optocoupler+12V relay?
I'm not a real expert in electronics but I'm going to start a new project that has completely captured me.
I need to drive a 12V pump with my Arduino Uno. The pump is "Dp0102" (12V, 0.7A). To power ...
- 73
7
votes
2
answers
11k
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Problems with homemade RS232-to-TTL converter board based on TI's MAX232
I've designed an RS232-to-TTL converter board based on TI's MAX232 IC that I plan to use to program a few custom Arduino boards that I have. However, I'm having trouble with the board and I'm hoping ...
- 6,204
7
votes
1
answer
32k
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PNP high-side transistor switching with microcontroller [duplicate]
Up to this date I was working with NPN transistor with micro controller and it was working fine. But here I need a PNP transistor.
Does any one can tell me is that the above configuration is ...
6
votes
3
answers
10k
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Best way to control 130 - 140 LEDS with Arduino Uno 32/64 bit led drivers?
I am new to electronic prototyping and had a few questions.
I need to control 132 LEDs individually. I want to make 3 rows ( 2 rows of 60 and 1 row of 12) I think i can matrix them but i would still ...
- 61
5
votes
3
answers
29k
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How to connect 20 wireless sensors in one receiver with arduino?
I live in a house with many doors and windows and I plan - as an easy project - to be able to detect and see which door/window is open using simple leds. What I do not want to do is to have 2 or 3 ...
- 247
4
votes
4
answers
15k
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How to connect multiple of the same device to an Arduino using I2C?
I want to use two of the same magnetometer (HMC5883L) with my Arduino, but I cannot figure the code for calling each of them separately.
I have read online that connecting multiple devices is ...
- 227
4
votes
2
answers
2k
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LCA717 SSR connected to Arduino Digital Pin
I am trying to figure out how to go about using this LCA717 SPST-NO relay in my project. I will be sending 12V (car voltage) to a radar detector and I want to be able to turn it on/off whenever via ...
- 807
4
votes
1
answer
11k
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Calculationg base-resistor between microcontroller and transistor
I'm curious, when connecting my 2N2222 transistor's base to a PWM output pin on my Arduino, I know the Arduino can deliver a maximum of 40mA current. The 2N2222 only requires around 5 to 10 mA on it's ...
- 155