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24 votes
Accepted

Is soil moisture sensor corrosion normal?

If you think about what is happening you have a very hostile environment for electronics (moisture - sometimes large amounts, soil PH and electrical current induced electrolysis) The Hookup Guide for ...
23 votes

Is soil moisture sensor corrosion normal?

Yes, this is normal for a DC drive configuration. You're effectively setting up an electrolysis experiment where the copper atoms on the positive electrode are being ionised, transported via the soil'...
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16 votes

DS18b20 temperature sensor not listed

I had the same problem with Pi B+ and solved it by adding a line to /boot/config.txt. Add the following to the bottom: dtoverlay=w1-gpio,gpiopin=4 found the solution at: www.raspberrypi-spy.co.uk
12 votes
Accepted

Can I use the 3.3v pin instead of the 5v pin?

The HC-SR04 can only be run with 5v(scroll down to specs). However, you can easily fix your problem if you have a breadboard. Assign one row as the 5v "rail" and attach as many sensors as needed. ...
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10 votes
Accepted

How to use the water flow sensor with raspberry?

Water meter pulse outputs are typically open drain. This means they are pulled to ground to signal a pulse and float high to an external voltage. As a quick check change the following two lines. ...
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9 votes

Using 5 volts on an mcp3008

First, lets check the characteristics of the MCP3008 again: Single supply operation: V_dd = 2.7V to 5.5V All Inputs and Outputs < V_dd + 0.6V (this should include V_ref) 200 ksps max. sampling ...
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9 votes

Looking for a starter kit for my 10 year old

There are a few things in addition to the pi itself that are required, and if you do not already have them, you would want a kit that includes them. Generally these are appropriately priced, but ...
  • 56.5k
9 votes

ESP 8266 and Raspberry Pi communication without an Internet connection

You could have the Raspberry Pi behave like a WiFi access point (using hostapd and dnsmasq, introductory documentation from the Foundation is here) with a static IP and then have the ESP8266 join the ...
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8 votes

How to Connect 6 ultrasonic sensors to a raspberry pi?

The following code will scale to multiple sensors. If you want all triggers to be at exactly the same time then connect the same GPIO to each of the triggers. Use that GPIO for the last sonar's ...
  • 67.9k
8 votes

Is soil moisture sensor corrosion normal?

Yes, it's normal. One electrode (the anode) will oxidise. That said, it shouldn't happen so quickly. I guess you have the sensor powered constantly. That means you always enable corrosion. What you ...
  • 2,919
7 votes

Do I have to connect a resistor to my DHT22 humidity sensor?

It seems necessary for reliable readings. I started my project without pull up resistor and the humidity measurement started dropping down. It may start correctly but deterioate later. Since I was ...
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7 votes
Accepted

LM35 temperature sensor not listed

An LM35 is not a 1-wire sensor. Its output is an analogue voltage proportional to the temperature. The Pi has no analogue inputs or outputs. You will need to use an ADC to read the sensor.
  • 67.9k
7 votes

How to read Analog 5V sensor ouput with Digital 3.3V GPIO?

For the analog sensors such as the photoresister and the hall effect sensor (and most likely others as suggested in the comments), you can supply them with 3.3V and still have them work correctly. ...
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6 votes
Accepted

Do I need a current limiting resistor in series with a magnetic door sensor?

Logic levels are detected by input pins. The difference between an input pin and an output pin is that an output pin has a specific voltage applied to it. An input pin does not, and when not ...
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6 votes
Accepted

Difference between .../thermal_zone0/temp and .../thermal_zone0/subsystem/thermal_zone0/temp?

lrwxrwxrwx 1 root root 0 2016-02-19 22:24 thermal_zone0 -> ../../devices/virtual/thermal/thermal_zone0 lrwxrwxrwx 1 root root 0 2016-02-25 17:31 /sys/class/thermal/thermal_zone0/subsystem/...
  • 54.8k
6 votes
Accepted

Connecting DS18B20 temperature sensor with RJ45 connector?

Connecting the DS18B20 to the Ethernet port would either not work or the effort to make it work (even if it was possible) would be excessive for someone starting out with a Raspberry Pi. As you state,...
  • 1,826
6 votes
Accepted

nutrient sensors for hydrophonics with raspberry

You need a TDS (Total Dissolved Solids) meter (aka EC/PPM meter) for measuring the nutrient content in your water, and you should also have a pH meter for maintaining a proper alkaline/acid level. I ...
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6 votes
Accepted

Scaling of digital reading of pressure sensor

Linear for the win! y = (slope * x) + intercept is the classic linear formula, in your case, x=sensor, y=bars, so the formula becomes bars = (slope * sensor) + intercept ... and you have two data ...
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6 votes

Is joining NEO6MV2 module and RC 522 module together to Raspberry Pi possible?

Short answer YES. The GPS module uses Serial = Yes you can do that with a Raspberry Pi https://www.raspberrypi.org/documentation/configuration/uart.md The RFID module uses SPI = Yes you can do that ...
6 votes
Accepted

How to connect multiple sensors to an rpi with the I2C?

I2C is a bus system and allows you to connect multiple sensors to the same pins. The master system (the Pi) lets the sensors know who should respond by placing that sensor's address on the bus. In ...
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5 votes

How can I control Lego motors?

There is BrickPi+ helps you connect LEGO sensors and motors to the Raspberry Pi and replaces the MINDSTORMS Brick. http://www.dexterindustries.com/brickpi/
5 votes

Do I have to connect a resistor to my DHT22 humidity sensor?

I use a 10K pull-up from pin 2 (DATA) to pin 1 (VCC), and always use 3V3 to pin 1. On 5V the sensor heats up a few degrees celsius. Also, pay attention to nearby heatsources (laptop, your breath, ...
5 votes

Sensor to detect water/liquid level

I found this Raspberry Pi water level meter - should answer the question is there water or not , but also a level indicator , like a measuring cup. 12" eTape Liquid Level Sensor https://www.adafruit....
5 votes
Accepted

How to connect a 12V fan sensor wire to the Pi

The yellow wire would normally be an open collector/open drain output which reads low as the magnet nears the Hall effect sensor and reads high otherwise. As an open collector the yellow wire will ...
  • 67.9k
5 votes
Accepted

Soil moisture sensor compatibility

The link you give is to the soil sensor which is not an Arduino. Did you mean to ask whether you could use the soil sensor with the Pi? Yes you can but to get analogue results you'd need to add an ...
  • 67.9k
5 votes
Accepted

Is the Raspberry Pi suited for sensor and voice recognition project?

From the given project description I'll jump for: Yes, it seems reasonable that a RaspberryPi can handle this project. Accelerometers and gyroscopes can be connected via the GPIO pins and the ...
  • 15.6k
5 votes

Can I use the 3.3v pin instead of the 5v pin?

The sensor datasheet will tell you the permitted input voltage range. Although you will get results by powering the HC-SR04 from 3V3 the results will not be reliable. If you want accurate readings ...
  • 67.9k
5 votes

Sensor Question

The DS18B20 is a digital sensor using the Dallas 1-wire protocol. If you just want to get figures to play with you could, as you say, connect an ADC and twiddle a pot. However a simpler, and perhaps ...
  • 67.9k
5 votes
Accepted

Is there a way to attach multiple serial port devices to a single raspberry pi?

You could: utilize a couple of USB to serial adapters like this one. you could use a microcontroller that has multiple serial ports (e.g. arduino mega) to gather the data and transfer it to the Pi, ...
5 votes

Slot car races time recording

You can repeat this schematic, assigning a GPIO port for each lane. The HAL sensor will require a magnet on the car, however, on my testing the magnetic field from the engine was enough to trigger ...
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