5 PCS Optocoupler Isolation Board, Icstation DC 12V Optocoupler Isolation Module EL817 1 Channel Opto PNP NPN Signal Converter, Isolator High-Level Trigger 80KHz

I have been working on building a small desktop CNC and one part I had some issues with was electrical noise interfering with my end stop switches. A common way to deal with this is to use an optocoupler and this one fit the bill perfectly. These boards are cheap, easy to use, and give you a lot of flexibility with how you want to wire up your machine. In my case, I am using a set of KY-003 hall effect sensor modules (Also sold on Amazon by DAOKI) which are powered by 5v. When activated, they pull the output pin to ground. I was able to easily wire one of these into the optocoupler board and use a small pullup resistor to make sure the isolator received full voltage ranges. The output of these isolators was pretty easy to hook up to the Shapeoko motor control board I'm using.Over all, these boards are pretty good and are well worth the small cost compared to the cost of breaking more end mills or a failed machining operation.

I'm using this to interface 24 VAC HVAC signals (Fan, Compressor, Reverser, Alt Heat, etc) to an Arduino (actually an ESP32) board. I used the 24-to-5 volt board here, but wired the output side with 3.3 volts off the ESP32 board and it works fine.Be aware that if your input signal is AC then the output side will be 60 Hz pulsing DC, so you'll have to deal with that somehow. I imagine I could put some filter capacitors on the output side but I'm actually handling it in software.I'm very pleased with this board as it's helped me find a problem with my heat pump (compressor short-cycling in colder temperatures caused by the low refrigerant pressure switch triggering) without me having to sit outside all night waiting for it to happen.

I use these to monitor signals on an ESP32 board that can only accept 3.3v logical levels. I have used them to monitor 5v and 12v signal lines and they've been working for almost a year now. Will buy more when I run out.

1: I had to use two in series to invert the signal. and then had to add 150k in series with the vcc to get a logic 0 out of the 2nd one, after that it just worked.

I was impressed with the quality of this board. I purchased the 24 volt version and find that it even works well at 12 volts. My need isn’t for high speed so I didn’t test that, but other reviews have stated that it could be driven pretty fast and give some specs. This board is perfect for interfacing long wire runs on an alarm system to a 5 volt Arduino or other micro-controller, and the LED status indicators let you see at a glance what’s going on. It’s worth noting here that when an input is energized, the corresponding output is driven LOW. All “pro” and no “cons” from me on this board.

I bought these hoping they would work for capturing a model railroad DCC signal and feeding the output into an Arduino for use with the DCC-EX system as a decoder. The schematic looked correct but the opto-isolator chip was different than the known working 6N137.After hooking everything up I looked at the output of the coupler and did find a 8Khz signal, but it was so distorted and out of phase it was not usable for the DCC decoder. I’m sure it works well for other purposes.

I'm using the 24V to 5V version to step down and isolate a 24VAC signal to 5VDC to feed a microcontroller GPIO input. As others have noted, doing so will result in a square wave 5V signal so counting edges with an ISR will be needed to know if the input is present.The 4 inputs are completely seperate from each other (other similar products assume a common negative input pin).The output power supply is completely disconnected from the input pins (there is no connection of the output ground pin to the input negative terminals)

This is a perfect interface to isolate your microprocessor board (Arduino, Respberry Pi, or other dev boards) from desired inputs. Micros are very unforgiving in over voltage, which could be very common when measuring inputs from all sorts of devices. This part will electrically isolate/protect your micro from unwanted power surges.