I have an existing WLED pcb I made, but want to make it lower power so shutting off the led strip when not in use and adding a switching reg. I want to keep the board size small so was wondering if anyone had tried putting a N-channel Mosfet to switch the GND on leds to shut them off. (rather than using relay on 12v)
has anyone tried this? I could use P-chan on the 12V side but that needs a few more components so would prefer n-channel option.
Hi!
I also have an N-channel mosfet board but opted for a standard relay for one of my lights once I learned the mosfet would interrupt the ground. In that case space was not a concern, but I would have liked to get rid of the clicking noise of operating the relay. Oh well…
Generally with addressable LEDs it is the consensus that when handling you should first disconnect data, then VCC and lastly GND (as reference, the Adafruit Uberguide emphasizes this). Disconnecting only GND can allegedly damage the LEDs. I once had a ground cable solder joint come loose and in that case the affected LED strip (SK6812) did not break. It did however appear to draw some power from the data in line, lighing up in a faint red. So you can give it a try, but I would definitely not incorporate it into the PCB design. P channel might be your best bet, although i’ve heard they have slightly worse efficiency than N channel.
Thanks,
Don’t want to damage the LEDS 
Will look at what i can find as a cheap Solid state relay or MOFET for turning 12V.
There is no such a thing as cheap solid state relay 
Gone for a P-Channel Mosfet.
Have to wait for slow postage, but should be able test/use before end of month.
Like to hear from you after testing.
PCB’s arrived today 
Build one up, should hopefully get time to test it over the weekend if it rains.
Is that a wago box?
Yeah 
, Cheap and keep the cables all lined up.
Hmm. Gelbox?
Running at full power where the mosfet is going to generate the most heat full white, the mosfet after 1h was 38 degrees which is a good sign.
Id be interested to know what other peoples standby power of there wled boards for comparison.
The mosfet I used was 33p P-chan mosfet getting Rdson ~3mΩ
This is the main source of heat (current^2*Rdson) so you could spend more getting a lower Rdson depending on the current draw of the project.
These leds surround me bed so I wanted to make it efficient and didnt want a clicky relay.
I’m just a little frustrated. You have only 21mA consuming by your board. How it’s possible? Are you able to connect to your WLED instance while you in standby mode?
yeah still responds to alexa/app. That’s just the switching 3v3 reg running, I could measure what I’m actually using at 3v3.
I have a 5V ldo for the signal out but that gets turned off with the 12V feed which will be saving some extra.
Nice. I just wonder cause usually it’s a 55-65mA min in idle.
The 21mA is @12V which would be around those values @3.3V I don’t want to desolder this one so ill do some extra reading when i build up another.
Oh now it’s make sense
Just did a measurement on 3v3 rail, current 64mA
Do you have a measurement of your boards at 12V? would be interesting to see difference.
I feed my board from 5V so now I see your measurements is almost as mine, within few mA
Hello,
maybe could you say which P-chan Mosfet you used?
Regards
Ulrich
Sorry I think I used one that I found in the office and looked up spec after. So not 100% sure on on
If you look for pchan MOSFETs on farnell/rs you should get lots of results that you can filter by Rds resistance.
I’ll have a look through my history when I’m home and see if I can find the exact one.
On another note if I am considering designing a triac based solution to achieve a lower standby consumption when I get some free time.
