3Pcs 1Channel AC Optocoupler Module 220V Voltage Detect Optocoupler Isolation Microcontroller TTL Level 3V-5V

Works as described - as a voltage detector. Very sensitive. An input voltage of just 20 VAC is enough to turn on the optocoupler and trigger an input on my Arduino Uno. Also note the full-wave rectifier and capacitor on this device. It rectifies and filters the input before the optocoupler. That means this cannot be used as a zero-crossing detector. It also means that there is a slight delay between application and removal of voltage and the switching of the optocoupler, since the input resistor and the filter capacitor form an RC circuit.

I tried connecting it to 3.3v from Raspberry PI but the ON signal was never above 1V and therefore Raspberry PI considered it to be LOW still. Only by using 5v input I was able to get just above 2v that was reliable to act as a digital on/off signal.

I'm using this module to read in the 120V off of a relay that turns on the drum motor in my clothes dryer. I had to use a resistor to bring the lower voltage sending threshold up, like it was suggested by another rlreviewer here (thank you kind sir). Overall the thing works exactly as I expected.

Not as pictured. the 3 items are not separate they are on a single board and must be carefully cut from each other.

Hooked one up through what I thought was a dry contact switch, it kept indicating there was power even though the switch was off! I figured out that since the switch was illuminated, that leaked a tiny amount of current through the switch. So good module, quite sensitive.

The media could not be loaded. I'm a person who likes to modify everything to suit my purpose better. That's why I really line this opto isolator with discrete components instead of surface mount component. I've included a schematic for those who are so inclined. This isolator also works on DC. As shipped it turns on at about 40V, way before you see the LED light. Turn on is below a half milliamp and the LED can be very hard to see. If you want to raise that voltage a resistor of 2K to 10K can be placed across the opto isolator LED as shown, pins 1 & 2. Doing so will make the LED more visible at turn on. The 10K pullup resistor makes this quite sensitive. You have the option of only running two wires if the connected device has internal pullup.This device works equally well with a DC input. For a sharper transition at a fixed voltage, the 150K ohm resistor can be replaced with a zener and resistor in series. The opto and LED in series represent about 3V offset. There is a 5.1V zener across that for protection. I can't see that it will ever do anything as the LEDs make good zeners and the voltage should never climb much over 3V. Just remember to use that 3V in your calculation. Size the current limiting resistor so that any excessive voltage keeps the current below 5ma.This device is fine as it is. For those with the skill it is easily modified for many other applications.

They works with 24VAC using a 4.7K 2W resistor piggy-backed onto the existing 100K 2W resistor, so to lower the VAC input, just piggyback a lower ohm'age resistor. Using this to monitor the 24VAC of my thermostat connected to Arduino UNO; connected to white wire (heat) and C-wire (common). Unfortunately, the 1 channel version is MISSING the red LED like is used on the 3 channel versions!

Arrive in a branded bag which does not strike me as being anti-staticWith a VCC of 5V:I found that the output was high (5V) with no inputWith 35VAC on the input the output was 2.5VAt 60VAC input the output dropped to under 200mV (off)The circuit has an unused Zener on the high voltage side, yet the circuit could use a Zener in the case of using 24VCC to cap the output V to 5V so as to operate TTL without the magic smoke on the low voltage side. Had someone Ok'ed the addition of a Zener and someone placed it on the wrong side of the circuit perhaps? Who knows.Nice to see TH parts for easy tweaking