Diode for inductive load protection when using relay module

Other Hardware General Electronics
1

Is it necessary to put a diode to protect against inductive loads when using this relay module: https://electronica.in.ua/ua/p1530391818-modul-rele-optorazvyazkoj.html?source=merchant_center&utm_source=google&utm_medium=cpc&utm_campaign=20496384634&utm_term=&utm_content=&utm_position=&utm_matchtype=&utm_placement=&utm_network=x&gad_source=1&gclid=Cj0KCQiA57G5BhDUARIsACgCYnzr1Hc-_r7JZN803t2zLyvyxUq7UavU_WRtJD4V1JCbb_WtvSx0odUaAq3NEALw_wcB

2

Yes, if you have a DC load. You should add one to extend the life of the relay contacts.

... There's probably a diode on the board to protect the Arduino and on-board driver from the relay coil's inductance, but they don't know what you're connecting to the contacts and they don't know the polarity.

3

I need to connect 2 devices via relay, which should work in turn. I have drawn a wiring diagram. The diode has a gray stripe which is the cathode (-). Is this diagram correct? I am new to the world of electronics, but I need to do a small project.

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Thank you for your response!
ps: DC load

4

Yep!

5

So the diode will only protect the relay contacts from wear?

6

High voltage spikes on the wiring of the inductive load could also lock-up or restart the Arduino. There are many threads on this forum asking for help with that.
Leo..

8

Thank you very much for explanation. I think, I'll add diodes. Can you tell me if my "wiring diagram" is correct?

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9

Most people switch the "+" power lead, rather than common or GND.

The diagram shows nothing to power or control the relay module, so it won't do anything useful.

10

The question was about correct connecting the diodes. The relay module is powered from the 5V/GND pins of the Arduino. What else do you need to know?

11

The inductive kick diodes are oriented correctly in your wiring diagram. The band indicates the diode cathode end.

12

Thank you very much, that's what I wanted to make sure of.