Youngneer 5v Relay Board Relay Module 1 Channel Opto-Isolated High or Low Level Trigger

I ordered the eight pack because I do a lot of Arduino stuff and this looked like the perfect way to drive almost anything from the Arduino ports that are severely current limited. Also, you can switch many voltage levels (both DC and AC). I am currently working on a mister design for my wife's garden and need to drive an inline water valve that operates at 24VAC, 250MA. This relay looked perfect (and was after a minor glitch that had me befuddled for a bit).I picked one of the eight relays at random and hooked it up into my Arduino breadboard. The relay would not work. I messed with it for 30 minutes to no avail then tossed it in the trash and grabbed another. When put in the same circuit, it worked perfectly! I dug the first one out of the trash and compared the two. Close examination revealed the problem with the first one...it was missing the jumper on the HIGH/LOW level state setting for the trigger input. Needless to say, this is not a fatal problem since the problem is easily fixed with a tiny piece of bare wire...just irritating that it was missing.I can't speak for the reliability as I am still building the "production" model of one. When it is installed in the garden it will get a real workout, with many on-off cycles every day. After this summer season without failure I will pronounce it good to go. If I remember I will update these comments.

I bought 16 of these relays to use on a Raspberry Pi (RPi) project to control a 12VDC circuit (for the purspose of this review the 12V circuit is not that important, it is merely being controlled by the signal going to the IN of this relay). RPi uses a 3.3V logic, but I had seen in the Q&A that these relays would work with a 3.3V logic, so I decided to give it a whirl. My 5V pins on the RPi were being taken up to power a touch screen for this project (a problem that can be solved by using a 5V bus on a bread board or terminal strip), so I tried using 3.3V (pin 1 on RPi) to power the relay on the DC+. Using this method, only 12 of the 16 relays worked - 25% failure rate seemed a bit too high. I decided to try using the 5V on the DC+ and 3.3V logic signal from the RPi - to do this the 5V and 3.3V need to share the same ground. This worked perfectly - 16 of 16 work when 5V is used on DC+.So, in short, you can use these relays with a 3.3V logic, but for stability, it should be wired like this:DC+ : 5V DCDC- : Ground that is connects to both the 5V circuit and the 3.3V circuitIN : 3.3V logic signalHope this helps!

Most Relay Modules that I have seen do not have proper clearance between the relay coil pins and the relay contact pins. Most of the Relay Modules that I have seen actually route the Coil PCB Trace very close to the Contact Trace. I would not use those Relay Modules for anything greater than 48 VAC on the contacts. This board has the PCB routed out around the relay contact. This will allow it to operate safely with 120 - 240 VAC on the Relay Contacts. The selectable active high or active low input is a very nice feature. Also having a Terminal Block for the input is also an excellent feature, much more robust than the pins that almost all other Relay Modules have.

UPDATE 2: My mistake. There used to be relays like these that could be powered by 3.3V from the NodeMCU module, but not these. They require 5V. Totally my mistake. Using 5V and they work just fine.UPDATE: So I tested these passing only 12V, less than an amp through the relay. It would open fine, but not close unless you gave it a little tap on the relay. Tried repeatedly. The same thing. Only closed with a tap. Swapped it for another one. It did the same thing. Another. Another. Went through 6 until the 7th one worked. I don't expect it to last long either. They have swapped out the relay component for a new factory, and they are apparently just junk. Cannot recommend.I built an automated window fan that is programmed to switch on when the temperature outside is lower than inside, using an ESP8266 and a couple of temperature probes. I was testing out everything as I built is, and all seemed to be working. Sheen the outside probe got hotter, the relay kicked on, and the red LED lit up. However, when I put the fans through the relay, it started getting unreliable. At first it kicked on fine. But after it was turned off, it would not work reliably. The red LED would light, bit the fans would sometimes not come on. I discovered that if I removed one of the fans, nothing would happen. But if I connected again, then both fans would come on. They have well below the rated current for the relay, which is 15amps.

I’ve become quite a DIY controls & automation enthusiast in the past two years. I’ve built and integrated probably over 100 devices in multiple households and a few in commercial buildings. I like the simplicity of these modules. In my opinion the simpler the circuit; the points of failure are significantly reduced. I would have gave 5 stars if I wrote my review based on the first 5 of these I used because they were flawless. The last 3 however seem to be DOA.

Bought these to build an autonomous submarine - need to control the small motors and lights with an arduino. Set everything up on a breadboard, running motors forward and back. The first 3 relays worked great. But the 4th one didn't work. 5th one didn't work either. Spent an hour trying to figure out what I did wrong. Swapped out with one of the working circuits and.. Presto. Everything worked.SO the score so far - of 8 units in the pack, 4 work, 2 dead. Haven't yet tried the last 2. Pretty poor track record. I can't comment on reliability - that will come with time. But putting them in an autonomous sub leaves me a bit worried.The ones that didn't work had a very very week green light when connected to power. The ones that did work had a strong steady green. Assume the low-current side was somehow welded poorly.I would return them, but I can't want another 2 weeks for a replacement. Need to finish the project.

Has a jumper so you can set rather the unit state changes with high or low signal. Has screw terminals for relay (NC,C,NO) and for input; Coil +, coil - and trigger. great little product. The units I got have the generic SRD-05VDC-SL-C.