Hi all, I have designed a RGB LED strip control circuit where the red and blue LED is turn off and on after each time intervals and the green LED is left unconnected and pump control circuit it is also turn off and on after each time intervals.
For RGB, I am unsure whether my circuit is feasible or not as the RGB i am using is 12Vdc, 70cm long and from what i had googled, the RGB strip pins is connected to the individual pins of ESP/arduino but those are intended for colour control whereas mine is just turn on red and blue together after each time intervals and left the green is unconnected.
For pump, I am using 12Vdc pump and I am unsure whether my protection is sufficient and is the connection feasible or not.
I am using ESP8266 NodeMCU and I am trying to reduce the pins required as much as possible as I have other circuits that will be connected to it as well.
Thanks for you reply. I initially intend to use 1 mosfet to control all the 4 colour pins of the LED but I what read online is that different LED colous require different amount current. so i use 4 mosfet just to be on the safe side as I though that it might stress the mosfet and LED strip due to the difference in current. Or did misunderstood what I have read?
from what i can understand from your reply, is that if the ESP pin gives a high signal, only 1 mosfet will be able to turn the LED strip and the other 3 will not or did i misunderstood it?
The IRLB8721 is not suitable for controlling with an ESP8266 - see the datasheet, the lowest Rds(on) spec is for Vgs=4.5; it requires 5v logic levels. ESP8266 works at 3.3v. Hence, it will not be able to fully turn on the MOSFET. MOSFET will be partially on, conducting current, but at high resistance, and will overheat and fail.
Use a MOSFET that is rated to turn on with 3.3v on the gate, like the IRF3708 (IRF3708PBF), which specs the Rds(on) at Vgs=2.8v, making it suitable for use with 3.3v logic levels.
Depending on how many LEDs are on the strip (led strip is available with LEDs spaced as close together as they physically can be mounted, or with more than an inch between them, so 70cm could have only 20 LEDs on it, or 140 LEDs) you may be able to use one MOSFET. 4 is almost certainly excessive.
Freewheel diodes should be mounted as close to the motor as possible - generally you put them directly connected between the terminals of the motor.
Here is my hand drawn circuit. I hope it is clear enough. can i get away with my current mosfet as my LED strip is 60 LED per metre and probably less than 1A of current per mosfet(i have reduced to 2 mosfet) and my pumps is 300mA to 400mA per mosfet. i only have this mosfet in hand currently and this website like this stated this mosfet can use: N-channel power MOSFET [30V / 60A] : ID 355 : $2.25 : Adafruit Industries, Unique & fun DIY electronics and kits.
