SainSmart 16-Channel 12V Relay Module Board for Arduino DSP AVR PIC ARM

The Sainsmart 16 Relay board is an inexpensive bargain. The primary purpose is to isolate the computer from the outputs. RFI or spikes can travel down a wire into a computer and mess up the logic causing any output to go on randomly. This board provides isolation in the relays, the standard usually being 1500 volts and opto isolation on the inputs using an optoisolator diode and optical transistor driving an amplifier. The board is wired when the ground is connected between the computer and the relay board. This is the only power connection needed along with the 16 discreet inputs which operate the relay with a ground input to one of the 16 pins on the header of the board. The 5volt pins 19 and 20 are sufficient to provide power for the computer but the real purpose is to provide input power to run the opto-isolators. Apparently this board has been provided with either 5volt or 12 volt relays. You should check the relay marking before connecting power on the power input pins. The Relays are SPST non-connected contact types, so you may wire virtually any load, but beware that the PC board and the associated connectors will probably not really handle much more than an amp at up to 120vac or 36vdc even though the relay is rated at a higher loads for its contacts. A good input source is Elegoo Mega pins 22 to 55 or a string of 74HC595 serial shift registers. If you connect two relay boards, you will probably need to breakout the wires to prevent connecting a solid 5vdc source to an input pin on the Mega. Note that the Mega has a female socket and the relay board has a male socket. Twenty wire Multicolor flat cable with connectors is a good choice for wiring. Also note that the inputs support open collector inputs which permit wired "OR" wiring. Personally, I would not use the 5vdc pins for anything other than the relay board. For safety operation I would provide +12Vdc at about 0.8Amps or more. I use this board to power 16 slow motion Tortoise switch machines on my Model Railroad using a +12vdc and a +24vdc power source. You really don't need a schematic since the relay board is so redundant in its wiring. The 5 volt converter is a LM2576 12v to 5v 3 amp converter.

Ok, I admit it, it took me way too long to figure out how to hook this thing up. In case anyone else is looking at this and wondering how it works, here's how it gets hooked up: 1) The header pins on the bottom of the main picture get wired directly to the Arduino board. Connect one of the 5v pins to a 5v header on your Arduino and connect one of the Gnd pins to a ground header on the Arduino. Each one of the relays has a corrosponding header down there, too, which get connected to a digital output on your Arduino. You can run each wire individually or run over a ribbon cable to a project board and break it out from there. Either way, getting the header pins hooked up allows the logic to fire, and makes the lights work so you can at least diagnose/debug your program. 2) Next, the relay board needs a 12v dc input wired up to the blue terminals on the bottom. These are wired to the relays, which make the relays actually fire. The voltage magnetically pulls a piece of metal away from one pole to the other. This action makes a noticeable clicking noise, which is a little annoying, but also lets you know it's working. 3) Each relay has 3 terminals located along the sides. One side is normally opened, the other is normally closed. Use this to either make or break the circuit that you have wired up for your lights, motors, or whatever else is involved in your project that draws more than 5v or needs to be kept isolated from the Arduino board. So yeah, keep in mind that you'll need a 12v power source to actually make the relays fire. All in all, it's a very well put together board, and would make a great control hub for something like say... a model train set or robot.

I have had a hard time getting accurate (correct) specifications from SainSmart, so I wired it up and took measurements. So here are some specifications that we can all use: Overview: 1. The 12VDC input requires > 500mA. 2. The drive to each control input pin must "sink" 3mA when low (low = relay ON). By the way, this is a great product - awesome bang for the buck! Note the price has gone up (was $23.69) ... less "awesome" but still "Good" bang for the buck. ***** Input Power (12 VDC input)***** - About 8 mA is required with all relays off. - Each relay requires about 30 mA when on. - So max supply current is 8 mA + (16 x 30 mA) = 488 mA (actual measured was 500 mA) - Because one may use the board's +5 VDC output (2 pins) to power an Arduino/PIC circuit, use a 12V power supply that can provide MORE than 500mA (depending on your circuit's requirements). - Note that the switching regulator on the Relay Board should somewhat efficiently (say 70%?) convert the board's 5V power usage to 12 V power input requirements. For example: 200mA at +5VDC (1 Watt) does NOT mean the +12V supply needs to supply an additional 200 mA also. This is because 1 W of power from the +12V supply only requires about 83 mA ( 12 V x 83 mA = 1 W ); however at say 70% efficiency of the 5 V regulator, this goes up to about 120 mA (83 mA / 0.7) but NOT the full 200 mA. NOTE: The best way to discover what 12 V supply is needed (its max current rating) is to ACTUALLY MEASURE the 12 V input current while using a "test supply" that can more than handle worst case (with all relays ON) then buy the supply that meets your needs. Always use a modern "switching" supply (wall wart) because they are smaller, way more efficient, generate little heat, and normally use much less "vampire power". - The baord's LM2576 (+5V) voltage regulator is rated at 3 Amps; however, one should not push it this hard. The circuits powered by the 5 V supply on the Relay Board appear to only be the LED side of the opto-isolators. Driving an input control line low turns on an opto-isolator LED ... turning on its relay. Each opto-isolator LED seems to require about 3 mA (for a total of 3 mA x 16 = 48 mA). This should leave you with at least many hundreds of mA available to power your circuits off of the relay board's 5V output pins (two of them on the connector). ***** Input control pins ***** - Grounding an input control pin (logic low) turns on the associated relay. - The circuit driving the input control pin must be able to "sink" (drive logic low) about 3 mA of current (easy for most PIC/Arduino output pins). *** CAUTION *** When a pin is NOT driven low, it "floats" to nearly the +5 V that drives the opto-isolators. This means that the driving circuit (Arduino/PIC) must either be also powered by +5V, or if powered by the now common 3.3V (or less!), its output pins must be "5 Volt Tolerant" (see your micro-controller pin specs). Another option is use of a "5V tolerant serial port expander" chip like an MCP23018 (I2C interface) or MCP23S18 (SPI interface) ... where just a few micro-controller pins give you 16 I/O pins. These can be powered by 3.3 V or 5 V. They are a bit complex, but a simple "software bit banged" I2C or SPI interface can be used to control them. Finally, one could use little signal transistors (2N3904) for this isolation from the 5 V (MCU pin -to- a say 2.7K resistor -to- transistor base, emitter to ground, collector to relay board input control pin). Darrell Thayer

Received this relay controller a few days ago and it is absolutely amazing. The controller requires 12V of power and I used an older wall wart from a dysfunctional wireless router. It did take me a while to figure out how to get everything properly wired but after a little tinkering. A little help for anyone else that purchases this relay controller: 1. It needs 16 digital pins to independently control all the 16 relays. The Arduino Uno has roughly 10 usable pins so an Arduino Uno is not ideal if you want to control all the pins independently. An Arduino mega would be the ideal choice for getting everything running perfectly. 2. The female header on the controller has two ground pins and two 5V pins. Once the relay controller is connected to a 12V power source the controller will provide 5V of power on both of those 2 5V pins. Which means you wont need another external power source for the Arduino. One thing to note is that if you connect the USB cable after the relay is giving the Arduino 5V of power the USB will not connect. Disconnect the relay 5V pin from the 5V pin on the Arduino then connect it back to USB to solve the issue. 3. The relays are loud. If you're going to use this to control something that will regularly turned on or off you'll probably want to put it into some type of enclosure to keep it quiet. Overall this is a great product, I recommend it to anyone looking to control some Christmas lights or setting up a home automation system.

I'm using this board to power an electronic sign. The relay will control various lights to create an animation. First things first, there is no documentation included with the board; so, you're probably going to need to go to secondary sources like youtube (https://www.youtube.com/watch?v=CSs-he1Mk3k) to understand how the board functions. It's functionally simple, though. It requires a 12V 1.0A power supply to power the relay array. I used it with an Arduino Mega 2560 R3 board. Connect from Arduino GND to the Relay GND pin. Connect one or more output pins from the Arduino to the input pins on the Relay input pins. The voltage flowing from the Arduino to the Relay completes the circuit by flowing back to GND on the Arduino. You CAN connect the 5V pin on the Relay back to the Arduino 5V power if you want the relay's 12V -> 5V to power the Arduino. This is nice because you don't have to supply separate power to the Arduino but not required. You can test the Relay board easily. Plug in 12V power supply. Connect a wire from GND to any of the input pins. You should see the light next to the corresponding relay switch turn ON and hear an audible click. That will tell you right out of the box whether the relays are functional without having to connect an Arduino. I did not test the Relay board with a Raspberry Pi; however, I would imagine that as long as the power supply and the voltage from the pins are stable, everything *should* work fine. This device doesn't care who powers or controls it. There is one thing that you should be aware of. Since these are essentially mechanical switches controlled by electricity, there is an audible click when you flip a relay ON or OFF. If you've got these things turning ON and OFF repeatedly, they will chatter away pretty noisily. This isn't a problem for me because my installation is in a sign located (temporarily) outdoors; however, if you're planning on using it indoors, be aware of the noise. You might want to use a different technique (transistor, etc).

No issues with any boards I received, I have more than 5 running various aspects of my smart home for more than 2 years. For those that need help this is the easiest way to connect them to the Raspberry PI: The relays are triggered on when the pin of the relay is pulled LOW (0) volts. the pins are made for an Arduino but will work with the PI if you connect a 3V LED between the relay board and the PI GND pin on relay board ----------> GND pin on Raspberry PI Relay Board Pin------> LED Anode (Long Wire) / LED Cathode (Short Wire) -------> GPIO of Raspberry PI you will have to do this 16 times. This has the added benefits of; Indicator if relay is supposed to be on to mount in project box side/top (Unused just leave inside) Relays do not trigger ON when rebooting the PI Relays do not trigger ON when PI is off all parts are cheap and comparable with using resistors. How this works: When the LED is used this way it is essentially a device that drops the voltage by 3V. converting any excess power to light. The PI requires 3.3v maximum to its pins. This method reduces the 5v to 2v for the PI. (You can check with a multi-meter) When the PI GPIO is HIGH (ON) there is 3.3v at the PI and 5v at the relay board. Because the LED requires 3v to operate and there is only 1.7v the led does not conduct power and the opto-coupler in the relay board stays deactivated. When the PI GPIO is LOW (off) there is 0v at the PI and 2v at the relay board. Because the PI is forcing the pin low the LED begins to conduct, turning on, The current limiting resistors in the relay board keep the LED from conducting too much power (and burning out) and still provides enough to activate the opto-coupler causing the relay to activate.

Installed this in my virtual pinball machine to drive "Ford SW3" 12 volt solenoids that draw 3 amps. This is good, easy to use, product, but found that after a few months the relays tied to the flipper solenoids began failing. They have mechanical contacts that wear out and break over time in my application. After having single relays on two of these fail, I replaced this board with mosfet solenoid drivers. It's a good product - just not the best for my specific application.

I just ordered six more of these boards via Amazon Prime. They are an incredible bargain, and available for even less on eBay if you don't mind waiting a few weeks for shipping from China. Because of previous reviews, I examined these carefully and tested every one right away. All of mine had clean, excellent build quality, and every one worked perfect out of the starting gate. Many electronic products that come out of China are of poor quality, such as some of the Arduino clones, but this Sainsmart product is very high quality. There is a lengthy review of this module by Darrell Thayer, which provides a lot of measurements on current etc. I tested all of these values with my Fluke 177 and all of Darryll's numbers are spot on. I'm using these relay modules, along with an Arduino microcontroller and "Centipede" shift register board, to control turnout solenoids, accessories, and other devices on my model railroad. Incidentally, it doesn't say if these are rated for continuous duty or not. I powered all 16 of the relays and left them energized for a few hours, and while the relay housings were a bit warm to the touch, there was no sign that they were burning up. None of the chips were warm to the touch.

８個のアクチュエーター（DCモーター、電磁弁）のリレー制御に使っています。制御電圧は１２V、マイコンはArduinoMEGAを使っています。スイッチサイエンスのホームページから仕様を読んで、配線方法の確認は必要ですが、初心者でなければ簡単に配線もできると思います。 コストも低価で助かります。注意点としては、リレーが１６個もあるので、やや重くなっています。また、スイッチの動作は、アクティブLOWなので、始めのプログラミングの際に間違えやすいかもです。

bonne qualité générale. une carte sur trois présente des qualité de soudure discutable. mais ca fonctionne bien

Works great.. LED signal lights will operate without 12v supply.. it's being operated by an audurino controller for my Christmas lights and switches nicely

箱はありませんできたが、緩衝材と静電袋に梱包されて届きました。動作も問題ありませんでした。

動作的にはまったく問題ないのですが、リレー接点の端子に注意。 基板上にはA接点風の記号しか書かれておらず、参考になりません。 端子を手前、リレーを奥に見て、向かって左からNO、COM、NCとなります。 事前にテスターで調べてから配線することをおすすめします。