HALJIA PC817 2 Channel Optocoupler Isolation Board Voltage Converter Adapter Module 3.6-30V Driver Photoelectric Isolated Module

Quite happy with this product.Being an Electronics Engineer I traced the circuit through to see what it actually did.First from the Module Description3: The jumper cap can be used to realize whether the output terminal is high potential output or low output.This is incorrect removing the jumper separates the output connector ground from the board ground (connected to the input connector ground) giving proper isolation.Both Opto circuits on the board are identical.The Anode (pin 1) of the input diode goes direct to the Connector (inx), while the Cathode (pin 2) goes through a 3k resistor then through a red led to ground (& connector marked G).The collector (pin 4) of the output goes through a 3k resistor to the output connector (vx), while the Emitter (pin 3) goes direct to the output connector (marked G).The signal is inverted between the input and output..

Straight out of the sealed antistatic bag, one of the terminal blocks has pieces missing (they were not inside the bag). Fortunately I only needed one of the two channels for the project I bought this for, and I could have soldered if I had to, but this really is not good enough. No QA, apparently. Fortunately the one channel that I was able to connect to does work.

Shoddy build quality - terminal blocks are not fitted properly.I suppose these boards are cheap and if they worked well you might overlook the quality, but like other reviewers elsewhere I found faulty optos had been soldered in place which is not good.

On the product photo a 302 resister can be seen on both the input and the output!302 is 3Kilo Ohms!The input 3k resister is in series with the opto and on-board LED! (1.2V + 1.2V voltage drop)It should be 90 Ohm if using 3V for the opto, to work reliably.I found that the output was giving 13k resistance, due to the 3k output resister and high input resistance, which was not fully turning on the isolator.I don't have a SMD work station, so added a 100 ohm resister between the 0V input leg of the opto and 0V input screw terminal. It now works ok on 3.3V input.For those wondering, the strap pins select if 0V is common between input and output or isolated.Not sure why the wrong resister value has not been spotted. It may work at 36V but certainly not at 3V.Shame they do not either make separate 3-5, 12 & 36V models, or add a strap to select.There are single module units available, with different voltage input and they have a three terminal output, to give either a resistive or direct output.

Along with other reviews that say the jumper links the ground connectors of input and output, and does nothing to invert the signal as the seller claims, I also found that the two channels share the same ground on the input side, and this cannot be changed.I am having to use separate boards for each channel I want to be completely isolated from each other, as my application uses an open collector pull down, so I needed the IN to be at +ve, the out to got to the open collector, and then to ground when active. As the grounds are tied, it fails to work as two channels for me.

Cette interface me permet de commander un relais statique (12V/230V) à partir d’une sortie trigger (12V) d’un ampli audio. Elle convient parfaitement à mon besoin