4 pcs DC 5V 1 Channel Relay Module Board Shield High/Low Level Trigger with Optocoupler

need to add a jumper wire if you want to have both channels controlled by 1 input, but they work well and a bargain for the price - terminals are hard if you don't know to place wire to one side as the screw is in the middle.

I bought this item for my students and they used it in their Arduino circuits. Works very well with no complain at all

I'm using this with two Raspberry Pi boards (one a 3B+, the other a 2B) connecting both the 5V to power the solenoid board and using the PI 3.3V GPIO to turn on/off. One of the 4 units was defective out of the box but the others are working. For the money, they are a good choice. Note that there is a severe limit on the current available for GPIO switching from the Pi, so the single-channel model would be the only viable choice. I am able to use this to power a 3D printer on/off by switching the AC power using the OctoPrint PSU control add-in, which simply raises a configurable GPIO pin.

These are actually quite simple to use after a little digging. The datasheet is terrible but the manufacturer has placed these relays on a breakout board that allows you to use a HIGH or LOW signal to activate the relay. I'm using mine for a class project involving a temperature controller that turns on a fan or heating element depending on the temp. They are rated for up to 250V AC and use an infrared optocoupler to separate the digital control circuit (low voltage) from the analog output (higher voltage). Very happy with my purchase as many Amazon electronic components are very inconsistent in quality and reliability coming when they come from foreign manufacturers. Would recommend.

My use is to power up a USB power supply using a USB port on computer as trigger. I have some lighting that I want to always come on when the computer is powered on or comes out of standby. The PCI-E USB card I'm using powers down in standby so I'm running a cable from that to trigger this relay which will close the AC circuit on a USB power supply. I could've potentially powered them from the USB card on the computer but I'd rather subcontract this power demand to a lesser device. Using my inline USB voltage and current meter, (so-so quality, readings always seem appropriate and correlate with the load put on it but I haven't checked it against a VOM), standby current was too low to read and with relay engaged it showed 80mA. Resolution on this USB meter is only 2 decimal places so something under 10mA for unclamped state. I could've just used a 5V relay for this task but I haven't seen any with 1/4" spade terminals and it's convenient having a board to solder the 120V wires to. For the price I went ahead and got a 5 pack for future projects. I was able to use only USB power by connecting red(+ from USB cable) to DC+ and IN terminals, and black (- from USB cable) to DC- terminal. This initial use is just for "bling" but I can imagine many applications where having switch control conditional to a computer being on or off would be handy.

I installed two of these on my tractor for controlling a larger high current solenoid switch. I had to add a DC-Buck voltage regulator upstream of it, due to burning out the first one, since somewhat wild 12-14.5V was just too much for it (it worked fine for about a day, then died.) The second one has been performing flawlessly for a couple months now. 😀

Using these with the Octorelay plugin for Ocroprint to turn my printer and lights on and off. Working great!

I used one of these to change the cooling fan speed in the control cabinet on a CNC rig. Basically a macro in Mach3 toggles a pin from low to high. This activates the relay that in turn switches the cabinet fans to high speed when the rig is running and back to low when finished. Yeah a fancier PWM temp control is another option but for the cost this with a down and dirty two-speed arrangement for cabinet ventilation. And I have three left over for several other controls to be added!

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