Just because a power supply is rated at 20A doesn't mean the circuit will draw that much current. I'm betting the thread starter doesn't have 20A worth of LEDs here.

I have close to 500 LEDs in a strip, each strip has sets of 3 LEDs in parallel, connected in series, with the appropriate resistor. I'm definitely hitting close to the max Amps, and yes, they're 12V LEDs.

Yes the transistor gets hot, but not burningly so. It's rated at 30A so I think I'm fine there.

 

This is not even a circuit to begin with!

It's not? Why not?

 

Because the wires are floating for a lack of a better explanation. You should draw it properly like a square or a rectangle. This is how everyone draw the circuits.

 

Because the wires are floating for a lack of a better explanation. You should draw it properly like a square or a rectangle. This is how everyone draw the circuits.

You're right of course, but I'm just learning and I figured the community was smart enough to be able to figure out what I was trying to communicate without worrying about geometric perfection.

Thanks for the feedback!

 

I figured the community was smart enough to be able to figure out what I was trying to communicate without worrying about geometric perfection

It's not geometric perfection that we are concerned about, it's having the circuit diagram in a standard form that is familiar.
Having it it a non-standard form makes it more difficult to follow the circuit and detect any problems.

It's like having a sentence read from right to left instead of left to right or vertically instead of horizontally.
Or perhaps one in pidgin English.
We could all likely read it and understand it, but it would take a lot more effort.
And since you are the one looking for help it seems reasonable that you should exert the extra effort, not us.

 

I have close to 500 LEDs in a strip, each strip has sets of 3 LEDs in parallel, connected in series, with the appropriate resistor. I'm definitely hitting close to the max Amps, and yes, they're 12V LEDs.

Yes the transistor gets hot, but not burningly so. It's rated at 30A so I think I'm fine there.

Does this mean you've got it working now?

As for the current rating, those can be very misleading. To handle 30 amps, your MOSFET would require heat sinking. The 30 amp rating is a maximum which you shouldn't exceed, but it's not a guaranteed level of performance unless you make sure to keep it cool. In reality, the more important specs to understand are the ones regarding heat dissipation and drain source resistance (Rds-on.) Those will define the operating limits way before you reach the 30 amp limit. If you're putting anywhere near 20 amps through that, you should have a heat sink on it. If not, consider buying in bulk, cause you might go through a lot of them!

 

Does this mean you've got it working now?

I do, indeed. I wonder whether I should upload a photo or something, in case any other beginners stumble across this thread. In the end, I can't really point to what the problem was, to be honest. I think I was getting drain and sink confused.

Thanks for the additional information regarding the max ratings. I will need to learn more about heat dissipation and drain source resistance before long. I must not be hitting those limits yet, because I have not noticed any particular overheating of any of the components to date.