Review on Channel Optocoupler Isolation Isolated Detection by David Guliford

I was expecting to change the main resistors to a lower value to make them work at 120v. To my surprise, it works well at 120V. In fact, I put it on my variac and found that they turn on very hard even at 20V! What really bothered me in my project is that I use it to determine the start of the generator, but in my case it doesn't matter. But keep this in mind for yours! I think they work so well because there is a transistor on the low voltage side which should be pretty sensitive. I've seen other voltage sensors like this that don't have a transistor and use the optocoupler output directly to turn the logic on or off. It's nice that this module has two LEDs for each segment. One for the high voltage side and one for the logic side. The green LED on the HV side is very dim at 120V, but the little red logic LED always lights up crucially at any input above 20V. Actually great that I didn't have to change the resistors because they will run very cool at 120 v. . I've heard that large resistors usually burn to death with prolonged use, but this shouldn't be a problem for them at 120V. Will it remove enough to not activate the logic side until around 90V. Since I found that my application didn't need precision, I didn't go any further. Screwing a resistor in there wouldn't be easy, but still possible if you really need it. So far I'm very satisfied, mainly because I didn't have to make any modifications. I'm not really worried about longevity. In my application they are very lightly loaded and run at half the rated voltage for maybe 10 minute cycles at hourly intervals, maybe 4 cycles a day for a couple of weeks a year. But they seem to be built well enough. These are all pass-through components and there is good isolation between the high voltage and logic sides. Also, the mounting holes are in decent places on the four corners, away from any components. I used this with an Arduino Uno with 5V logic. Note that because I don't know how well it works with 3.3V logic. I think it's logic low (ground/0V) , when an input voltage is present. I don't remember exactly but it looks like it says in the description, it's not here at the moment. It also has a network of resistors to pull the logic outputs high when there is no input voltage. which is nice. Basically satisfied. works for me I hope my review will help you.