SainSmart 16-Channel Relay Module

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.

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.

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

Very impressed for the price. 16 mechanical relays, easily driven from any 5v microcontroller. It may seem slightly annoying to have to power it with a 12v supply, but at least it provides power to the microcontroller controlling it. It also doesn't come with the box, despite the box being shown in the product photo. I could see this being very disappointing to people who... collect... relay board packaging? My point is, you get a board in a antistatic bag in a bigger bubble wrap bag, the board switches lots of electricity and is controlled by any 5v device, and it's cheap. If you need to have a 5v device switch up to 16 large loads using a board that comes in an antistatic bag but not a retail box, and you don't have a huge budget, get this board.

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。

Awesome product. Perfect solder joints. No residual flux. No bridges. Can't beat it for the price. Will recommend to friends and will buy again!

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。