SRD-05VDC-SL-C not switching off even on power loss

Hello Everyone,
I already googled hours for a problem with an Arduino Nano, SRD-05VDC-SL-C and an LED lamp.
I used the tutorial Tutorial Button Debounce. The wiring there is not rocket science and the only difference is the relay and not an LED.

Here my sketch:

Everything works when using normal light bulbs, but if I let control an LED lamp, then the relay will not switch off anymore. It will even stay closed after removing all power from it. Only if I hit it, then it will go on its normal close (NC) state.

The LED lamp has the following controller inside:

Its description is:

Has anyone an idea why the relay won't switch off?

What I tried until now:

  • Replaced the Relay
  • Replaced the Arduino (even it is unlikely the problem
  • Used the code from the tutorial

I assume the LED lamb is magnetizing it or something else really weird!

Every hint is appreciated.

Try this relay’s power connection.
You can still use D13.

a problem with a …SRD-05VDC-SL-C…

In cases like this it’s important to realise, and to state, that you don’t only have a SRD-05VDC-SL-C. You have a module or breakout board containing a SRD-05VDC-SL-C, but it contains other electronics too. So it’s important to mention that board / module by name, and preferably to link to its datasheet, since they’re not all the same. Also important to make sure your Fritzing diagram uses the right symbol for that module…

Here my sketch

Just as a matter of interest, in Arduino-speak the “sketch” is the Arduino program, not the circuit diagram.

The circuit diagram in Fritzing is also called Sketch. In my post, I mean the circuit diagram.

You are right about the module. I am not using the bare relay. Honestly speaking I did not really think it is important, but it can surely be. I am using that one:

Unfortunately, I was not able to find its datasheet.

The part from Arduino is working fine. I can see the green LED turning on and off. The really weird thing is that the really keeps turned on even if I remove it completely from Arduino and its power supply.

Seen several threads here with contacts of these sugarcube relays sticking/welding together if non-resistive loads are switched. Tapping the relay seems to 'unstick' the contacts for a while.
Maybe you should use snubber circuits across the contacts with inductive/capacitive loads.

@wawa: It sounds reasonable. until your replay, I did not even know such circuits exist.

I will try it and post the results here.

I found other posts like Arduino Resetting Itself with Relay after understanding wawas response.

@wawa: Thank you again.

I will buy a finished RC Absorption/Snubber Circuit Module, like the one mentioned in the post:

It costs around 3€ in Germany.

As written, I will post the results here.