24v COB rgb 840 strip controled by Raspberry Pi

 fskrzycki You have a big problem 24+ volts and logic do not never mix.  I have one better than my buddy shabaz has AND you only need 1 part to use an optio-isolator anything in the 4N44 etc (there are tons of them on eBay,) will work just look at the collector voltage and current. ~~ C. Harrison

Update 9/3 I Fibed!   It has 2 parts, see the comment below. 

I like opto-isolators too, there are some fancy ones that can directly drive MOSFETs. In the end I only sketched one approach with transistors since unfortunately I didn't have time to provide additional circuit options : (

The transistors are less exotic I guess!, but really all of these approaches are a bit excessive for the use-case, because the Neopixel-like strips would eliminate all of the circuit (well, almost all - might still need to adapt the 3.3V to 5V logic levels).

 shabaz  Well, there are more ways to skin this cat.  level shifters cost $ while, your approach used more than a few parts, The optocouplers on eBay are about a half a buck each, buy 10 and save. but you will have to use a resistor in between the coupler and your Arduino's output pin (5v) the iso normally turns on at 1.3 volts so a quick trip to Mr Ohms or E= 1*R  so  R =( 5 -1.2)/20ma = 180Ω. But most likely get away with 220Ω ~~Cris H 

BTW I use this approach in my sim where the lamps are 28 volts ouch!  REMEMBER DO NOT USE A COMMON GROUND OR POWER SOURCE, or you will lose your galvanic isolation - this could ruin your week!!

 shabaz  Well, there are more ways to skin this cat.  level shifters cost $ while, your approach used more than a few parts, The optocouplers on eBay are about a half a buck each, buy 10 and save. but you will have to use a resistor in between the coupler and your Arduino's output pin (5v) the iso normally turns on at 1.3 volts so a quick trip to Mr Ohms or E= 1*R  so  R =( 5 -1.2)/20ma = 180Ω. But most likely get away with 220Ω ~~Cris H 

BTW I use this approach in my sim where the lamps are 28 volts ouch!  REMEMBER DO NOT USE A COMMON GROUND OR POWER SOURCE, or you will lose your galvanic isolation - this could ruin your week!!

the logic mosfets i ordered are rated to be maxed out@30v so i was not to concerned. my Pi is controlling the DC24v COB strip with  a GPIO setup for each color. Im using ChangeDutyCycle to control the color. pretty cool. The color wheel runs from 0-255 and CDC controls the current cycle of the mosfets with ratings 0-100%. I can generate any color by dividing 255 (100% power) into any color number than multipling that result by the number again. Currently the program will run any 1 color super bright for me (why i went with 24v) in an endless loop using the "while true" statement. The LEDs turn off fine when i break the loop. the program ends without error. 

the rub is after ai end the program. if powere is left connected to the strip, The LEDs turn themselves on to a yellow color.  interesting. i think the Red and Green MOSFETs are leaking.

when the project is complete. the python script will loop endlessly from startup and only break when a button is pushed to execute an "else" statement. which will be a sound wav file and some cycle color changes.

should i be concerned abiut the yellow? 

1. i'm using optocouplers to isolate the pi from the LED power source. I needed to create 3 circuit boards, on for RBG.  i connected them together at the power source input of the zenner Diode.  Will this be a problem with galvanic isolation?  also, do Zenner Diodes need to be placed into the circuit a particular way?
3.