8-Channel Relay Module

Experience: Software engineer, learning electronics with my Arduino. My dad is an EE talked me through all current measurements. SETUP: - Connect arduino powersupply 5v to VCC - Connect arduino Digital ground to ground - Connect arduino digital output to any IN1-IN8 - You're in business! CURRENT: I connected my meter in series and found I was drawing 64mA across the Arduino 5v power supply and 1.9mA across the Arduino output pin. I flipped it over and measured 7100ohms across the coil, meaning the coil is drawing 0.7mA at 5v. These numbers honestly seem a little low to me - e.g. I expected more like 19mA across the output, but 64mA across the power supply seems very reasonable with all eight relays drawing 400mA per the spec. Note: Arduino max power supply voltage is 500mA on USB, so you're good there too. PROS: - This won't blow up your Arduino. - I didn't realize this model had LEDs. I looked at the 4 relay model and the LEDs are bigger, but these are smaller and work great. - LED's in the circuit act as diodes. My dad told me when the field collapses on a DC coil it generates a negative voltage. If you don't have a diode in the way you could burn up your output transistor. - This has NC (Normal Closed) and NO (Normal Open) contacts on the high voltage side. So if you want your lights ON or OFF by default you can do that. It has a nice diagram on the board showing how the high voltage contacts are laid out. - Price - 4 mounting holes on the board if you need to bolt it to something! - Lot's of fun - you should buy one! CONS: - N/A OTHER: - The header PINs are really nice, but I only have male breadboard jumpers and need to buy some male-female jumpers from radio shack before I can hook this baby up to my xMas light setup!!

These are wonderful and a great value. These have both optical and magnetic isolation, providing a lot of protection to the inputs from electrical faults on the outputs. They work well with 3.3V and 5V logic (RasPi, Teensy, Arduino, ...), requiring little current drive. Very breadboard-friendly if you use a simple M/F jumper wire. They have indicator LEDs that can save you hours of problem-determination time, aid classroom demonstrations and reassure you things are working as expected. They're red, so someone might confuse them with error LEDs. The contacts have fairly low bounce and quick switch-over time. They have 3 terminals per SPDT relay, but they are soldered to the board, not on a connector. This is the only drawback I can find with this product. If you twist too hard, you can ruin the terminal. Fortunately it's a common header and easy to resolder.

This is a fantastic thing to have with Arduino. I honestly only bought this because I had a gift card and it looked semi interesting but I have really kept myself entertained with it. No regrets. Hook the relay boards VCC to the +5 on the Arduino, the boards GND to the Arduinos Ground and then just use simple HIGH and LOW digital pin states in Arduino with the board pins. Each relay has three terminals. One input terminal and the other two are for a normal-open output and closed output making this pretty versatile. The relays are very fast too. I wouldn't try to switch them below 40ms though (the fast parts in the video are 46ms on/off) since that may cause some wear or you may get some bad switching. These would be great for a christmas light setup if you're in to that. I still haven't figured out what I want to do with this in the long run but it is very cool and I can see a lot of potential in it. For now I just decided to make a quick sketch to a song (using only HIGH/LOW pin states and delays). I think I'll hook it up to some lights or something eventually.

I purchased this relay to work with my Arduino to experiment with running indoor Christmas lights to music. As most say, the documentation is limited, but enough information is on-line that it is fairly easy to get them running. I was switching on/off several electrical devices within about 30 minutes. Not a fault of the product, but they are very noisy, so for the "Christmas lights to music" purpose I had to place it in a box with sound proofing material. Most relays click when they switch, so when you have 8 of them banging away to music it's pretty loud. My conclusion is that using them for this purpose will wear out the relays pretty soon. If you're looking for relays for rapid switching, I'd suggest the solid state version, although they are lower power rating. My lights are 120 volt so I went mechanical. The product is very solid, assembled well, and works exactly as advertised. I'll probably re-purpose the product for controlling other high voltage items in the house. Based on my experience so far, I'd say it is a perfect device for home automation projects.

This 8 channel relay board works as expected. Note in order to take advantage of the isolators, you need a separate 5V dc power supply. In my application that was most certainly required. Otherwise the back EMF and or noise was coupled back to the Arduino and would crash it. An important thing to note is the connections on the bottom are exposed. If you are using AC, you must insulate them. In my case, the case that this went into does that. If not, its seriously dangerous to have exposed mains AC. DC is less of a concern if its low voltage low amperage. Still I would insulate either way.

I love it! It was a little difficult to hook up but does a wonderful job! It can be used as normally open or normally closed which was a little difficult to find out before I bought it. I purchased it to make an ag pump remote start. I have not completed that yet but I have tried it with my bedroom light! Using my raspberry pi and dataplicity and this wonderful relay I can turn my light on from around the world!

Let me start out by saying that the only reason I didn't return it is because it still worked for what I needed it to do, but a lot of modding was needed. I got this so that I could control objects with my computer. I thought, 8 objects, 8 relays, good price, so why not? What I didn't realize is that the inputs are not actually inputs. They need to be grounded to turn the relays on. The problem with this is that the parallel port outputs 3.3 volts on my computer, so it wouldn't work at first. So, I decided to keep the board (because 26 bucks for 8 high power relays is actually a good price) and just change it around. I used 8 NPN transistors to connect the "inputs" to ground (emitter to ground, collector to "input") and then 8 10K resistors to connect to the base. 3.3v at .26mA into the base grounds out the pin and the relay turns on. It works, but I was hoping for something that I could take out of the box and use, and NOT have to change on the first day. I see that a lot of people don't see what I am saying here. OK, what I was doing with it was using my parallel port on my computer to switch on 8 relays. Parallel ports have 8 data pins that can be set to high (+3.3 to +5 volts) or low (0 volts), but have a maximum amperage handling of only about 5 milliamps. The fact that the control pins on this relay board require voltage shunting (easily done by grounding the pins) to switch the relays on/off means that this board didn't outright work for my setup. So I took NPN transistors and connected the collectors to the relay board pins and the emitters to a common ground. I then soldered in 10K resistors onto each base pin of the transistors. Those resistors then received power from my parallel port data pins. The parallel port pins go high, the transistor activates, the relay board pins get shunted, and the relay turns on. Perhaps now people will start agreeing that this review is actually quite helpful...

Setting it up requires a little bit of engineering knowledge. This particular relay uses reverse signals (add "#define ON 0" and "#define OFF 1" to your code, then use ON and OFF to turn the devices on and off). Be very careful setting up the 110v side of it, you can never have to much insulation. This allows me to control up to 8 normal devices you would normally plug into a wall with my arduino. My father showed me how to solder the relay up to 8 power sockets and we mounted them into a power-socket-holder we found at home depot. Device works very well, loud click and on-board LED's let you know that the relay is turning on and off. The relay itself can be powered directly from the 5v output on the arduino.