PSU running through 3x LM350 to step voltage down to something like 7V for Red & 10V for Green and Blue LED's.
QuotePSU running through 3x LM350 to step voltage down to something like 7V for Red & 10V for Green and Blue LED's.No need to use a voltage regulator let alone three of them. That is the job of the constant current supply. However, the heat will be dissipated in the circuit's FET so you need to look at the power dissipation. This depends on your input voltage.
I have decided on the component values I want to use and have revised the drawing to add R1 as suggested in one post but is it really needed? Won't it just default to turn the LED on if no PWM signal present?
Generally we want FET's to switch hard and fast
A pull-up to 12V will exceed max voltage for the PWM pin and you don't want that (eliminate R1 from your circuit).
Question is will it work okay without R1.