I've recently gotten interested in electronics and so after doing some reading I've decided to have a go at building my own simple electronics circuit to control a 12V RGB LED Strip with wifi. I've chosen the ESP8266 chip, but at the moment I'm still focussing on getting it all connected.
I have a question and a problem:
About the MOSFETs:
I decided on mosfets after having read rants against the commonly used TIP120s, but for my application do I need to worry about the difference between standard mosfets and logic level mosfets?
I've found these two at local store: IRLZ44N(PBF?) and IRLB8721(PBF?) Apparently one is logic level and one's standard? Which do I use? They're the same price.
Problem with voltage input:
My LED Strip needs 12v, and the breakout board has a voltage regulator on board that takes in 4-6v. This means that I either hook up the strip directly to a 12v supply and find a way to step it down to 5v for the chip, or power the strip directly from 5v and then find a way to step up to 12v for the strip. Which way would you recommend? I assume stepping down is easier.
And with the chip drawing up to 500mA and the strip up to 1A, I don't think a linear regulator like a LM7805 would suffice; would a buck converter like the LM2596 work? Only thing that's stopping me is I've heard that due to the switching nature of buck converters they introduce a lot of noise and input voltage ripples to devices sharing the power supply. Do I need to worry about this if they're both connected to a 12v power supply and in the same enclosure?
EDIT2: Updated Circuit
EDIT1: Links for MOSFET datasheets as requested:
IRLB8721 – https://cdn-shop.adafruit.com/datasheets/irlb8721pbf.pdf
IRLZ44N – http://www.irf.com/product-info/datasheets/data/irlz44n.pdf
Best Answer
First of all, welcome to the world of electronics. Thanks for uploading a schematic, as it is much easier to read than a diagram. I have a couple suggestions considering your level.
Use low-side gate drivers
The ESP8266 chip outputs 3.3V logic signals that could not turn any standard MOSFET completely on. That being said, there are many great integrated solutions to address this problem such as low-side gate drivers. One great example is the cheap and easy-to-use TC427. It is characterized for 12V operation and 3.3V logic inputs. Use \$ 1 \mu F \$ and \$ 0.1 \mu F \$ decoupling capacitors near the chip and you've got a simple but effective interface between your SOC and the FETS. You'll need two of them to drive three FETs (2 drivers/chip). As for the FET selection, at such a low current (about 333 mA per FET), it does not make a significant difference, although the IRLB8721 does have lower ON resistance and gate charge, which should generally decrease global power loss.
Use a 5V linear regulator
For the sake of simplicity, start with a 3-terminal linear regulator (7805 type). As Transistor said, it is inefficient but manageable at currents below \$ 100mA \$. Switching regulators are complex and should not be built by beginners. Anyhow, typical current consumption for ESP8266 with 1024 packets at -65dBm (much likely your situation) is 62mA, which should dissipate \$ 0.434 W \$ in the linear regulator. Use a proper heat sink to keep it cool. If you plan to transmit with the ESP8266, power will increase and you will need a proper switching regulator (off-the-shelf, do not build one from scratch at this point).
Stay safe
Double check your connections before applying any power. Have fun with this project.