4 Channel DC 5V Relay Module for Arduino Raspberry Pi DSP AVR PIC ARM

Excellent board for Raspberry Pi. Assuming you have a solid power supply, you can run this board off the +5v provided on the pin header (Pin #2). The relay board is fully buffered, meaning that the relay coils are not directly driven from the GPIO pins which protects the Pi and means that this board is plug and play. If you're going to be doing a lot of work with the RasPi, I highly recommend a USB voltmeter/ammeter combo so you can monitor your power usage. At full load, you want to ensure that your voltage on your USB port is as close to 5.0VDC as possible, anything less than 4.65VDC will cause problems with the Pi and stability. Your amperage should never exceed the USB power supply's capability. I use a 2A (2000mA) power supply and with full load (all relays on), the board + Raspberry Pi B+ only gets to .56A (560mA) so I'm well with spec. With all relays off, I pull about .24A (240mA)HOW TO HOOK IT UP:The board has a six pin header labeled GND, IN1, IN2, IN3, IN4, VCC and a two pin jumpered header labelled VCC/JD-VCC. Leave the jumper installed. For GND, you can connect to any of the GND pins on the Pi's header (Pins 6,9,14,20,25,30,34,39). For VCC, connect to pin 2 (+5V). Connect each of the IN pins to a GPIO pin (I used GPIO 8,9,10,11 which are pins 24,19,21,23 respectively).HOW TO CONTROL IT:Use Python (should be available in your RasPi distro) along with the RPI.GPIO library. You'll need to run your scripts with sudo as manipulating the GPIO pins requires root access. You can set the GPIO pin using GPIO.output(PIN, True) to turn off the relay, and GPIO.output(PIN, False) to turn it on. My only nitpick is that the logic is backwards. Driving a GPIO pin high (TRUE), should turn on the relay while driving the GPIO pin low (FALSE) should turn it off, but it's easily fixed in software.Pros: Plug and play, just works. Will be getting more of these. You don't have to worry about building interface circuits, transistors, load calculations down to the mA or anything overly complicated. Basic research into the GPIO library for Python, a couple of GPIO pinouts for the RasPi and I was up and running within minutes.Cons: Logic is backwards, you have to send a GPIO pin LOW to turn on the relay but this is a very minor thing and can be easily fixed in software.Verdict: If you are looking to be able to control equipment using a Raspberry Pi, this is the board to use.

Very Happy whit my purchase

This is a solid board that is easy to use. It can be triggered by either 3.3V or 5V Arduinos and probably most other controllers. (3.3V setup is different than 5V setup) I used this board with an e-cig cartridge and high amp batteries to create a steampunk hat that puffs "steam".Simple Setup (using Arduino UNO):Connect the VCC to the 5V power supplyConnect the GND to the ground on the controllerConnect IN1-4 to DIO pins on the controllerLeave the JD-VCC to VCC jumperConnect your common to the center pole on the relay and your feed line to the left pole for Normally Open (off) and right pole for Normally Closed (on).Program your controller to digitalWrite(pin, LOW) when you want the relays to switch.Pros:Simple design10A relays are good for most requirementsCompactCons:None

1 star off for no documentation but otherwise a very cost effective relay board. Provides optical isolation and some degree of physical isolation. I would judge this board suitable for light-duty AC Mains usage. The unit works well with my Raspberry Pi 2 and Pi 3. I will be buying more.Addendum for Pi users. When the Pi first boots the GPIO pins are not yet defined as outputs. The LEDs on the relay board are dimly lit which suggests there are pull-down resistors in operation. However, once you define the GPIO pins as outputs the relays immediately switch on. You can turn off the relays by sending the GPIO output high (GPIO.output(xx, True) where xx is the corresponding pin number).To resolve these issues I decided to add inverters between the GPIO pins and the relay card. For this I chose a quad, 2-input schmitt NAND gate device (4093B). I also added pull-down resistors (47k ohm) to the 4093B inputs because when you cleanup the GPIO library (under Python) or shutdown the Pi, the GPIO pins are floating - this leads to undesirable relay chatter without the pull-downs. You can power the 4093B from the 3.3V power supply on the Pi's interface. You can probably substitute a 4011 Quad NAND for the 4093 but I haven't tried it. The picture shows my inverter card which solders direct to the relay card.Using GPIO pins 23 through 26 the code to initialize then turn on relays 1 and 3 would look something like this:import RPi.GPIO as GPGP.setmode(GP.BCM)GP.setup([23,24,25,26], GP.OUT)GP.output([23,24,25,26], [True, False, True, False])...to turn on / off relay 2 would be:GP.output(24, True)GP.output(24, False)...GP.cleanup()