Motivation: A way to be sure a relays in hand are opto-coupler ones.

Reason: Due to AC power interference ( on the client side of relay - an AC motor ), I'm afraid wrong ones were sold.

Edit 1:

Attach 2 kinds of items both ( and there is some more )

Example #1

Example #2

Edit 2:

Adding pics: tries to overcome EMI on relays ( one try - is sheilding wire only, second try - shield relays box) shiled wires

shield wires

**edit 3: add schematic **

wring diagram

  • \$\begingroup\$ Google it's part number? \$\endgroup\$
    – Eugene Sh.
    Commented Jul 13, 2018 at 15:13
  • 3
    \$\begingroup\$ The electromechanical relays making "clicks" when toggled \$\endgroup\$
    – Eugene Sh.
    Commented Jul 13, 2018 at 15:18
  • \$\begingroup\$ No, you should search for the manufacturer's datasheet on the actual relay. A link to aliexpress for an assembled module is not helpful to anyone. \$\endgroup\$ Commented Jul 13, 2018 at 15:18
  • \$\begingroup\$ I'm looking for a positive way ( say I don't believe what seller say ) \$\endgroup\$
    – guyd
    Commented Jul 13, 2018 at 15:19
  • \$\begingroup\$ ofcourse it clicks \$\endgroup\$
    – guyd
    Commented Jul 13, 2018 at 15:19

2 Answers 2


In your examples, the part labeled "Songle" is an ordinary relay.

The part with 4 pins with the two sides spaced fairly wide apart, beige colored in example 1 and black in example 2, are the optocouplers.

You can google the part numbers marked on these parts to find the specifications and see if they match what the board vendor told you. This of course assumes they don't use counterfeit parts.

  • \$\begingroup\$ great- that what I was looking for. I'm asking since after some switches ( i'm guessing ) some interference on relays freeze my Rpi ( and it is not code for 100%) \$\endgroup\$
    – guyd
    Commented Jul 13, 2018 at 15:26
  • \$\begingroup\$ Can you include a photo of your whole setup? For example, how long are the wires from the Rpi to the optocoupler? How are the wires separated between the load side and control side of the relay board? etc. \$\endgroup\$
    – The Photon
    Commented Jul 13, 2018 at 15:27
  • \$\begingroup\$ Added to question \$\endgroup\$
    – guyd
    Commented Jul 13, 2018 at 15:34
  • \$\begingroup\$ What are the wires connected from the RPi directly to the load board? \$\endgroup\$
    – The Photon
    Commented Jul 13, 2018 at 15:53
  • \$\begingroup\$ wall switch : UP/OFF/DOWN (part of the original winow's electrical shade ) \$\endgroup\$
    – guyd
    Commented Jul 13, 2018 at 15:55

I'm afraid you are in significant trouble if you cannot tell what the parts are on the boards you have purchased.

In fact the images of both your boards clearly show the part number of the relay used, and clearly have an opto-isolator onboard.

enter image description here

The most significant difference between the two boards is one is for 12VDC and the other for 5VDC.

You give no indication of how you believe EMI is causing your problems (whatever they are) but the boards you point to are NOT equivalent.


In terms of your design What powers your Rpi? It is quite possible that any surges on your motor side may well impact a small SMPS and reset your Rpi.
You would be much better using a zero crossing SSR than a conventional relay. The points on the conventional relay may open/close at any time, so may close when the voltage is very high on the AC waveform.

An SSR will close/open only when the AC voltage is low (or at least the current is approaching zero if there is phase shift).

  • \$\begingroup\$ thank you for you kind answer. by mistake I put another pic ( which I also purchased ) for another application. they are BOTH 5VDC. BTW - Optocoupler chip was the one i wasn't to spot, which was my main question. regarding your second question- how did I device it is a EMI - firstly- it is not CODE, nor all HW ( that was all replaced ), and using same setup with 220 VAC on the table- is working flawlessly for long long time and operation. on the other hand- when moving it to window's motor setup - as you can see in pics - after few clicks ( code switch or physical switch ) rpi freezes \$\endgroup\$
    – guyd
    Commented Jul 13, 2018 at 16:20
  • \$\begingroup\$ With no schematic is it impossible to offer an opinion on what may be wrong. Your build is not what one might call professional in any way. \$\endgroup\$ Commented Jul 13, 2018 at 16:39
  • \$\begingroup\$ added to question post \$\endgroup\$
    – guyd
    Commented Jul 18, 2018 at 5:34
  • \$\begingroup\$ @Guy.D Added to answer. \$\endgroup\$ Commented Jul 18, 2018 at 15:19
  • \$\begingroup\$ Rpi is powered using a standard 5vdc power supply and a USB cable. Since I was worried of the same thing, I tried to power RPI using a 5V battery ( same as ext battery chrage for iphone ), and same phenomena occurred, and it has nothing to do with common inlet power for RPI and AC motor \$\endgroup\$
    – guyd
    Commented Jul 18, 2018 at 19:04

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