# Wi-Fi controlled light; 230VAC - 12VDC/3.3VDC

I try to connect an ESP8266-12 and a 12V RGB LED strip to 230V AC. Based on this link, I've came to the following scheme. This will also be the first time I will etch a PCB myself.

The partlist will be as following:

Part      Value

C2        0.1uF
C3        0.1uF
C4        0.1uF
C5        0.1uF
D1        1N4004
D2        1N4004
D3        1N4004
D4        1N4004
F1        1A will be sufficient?
JP1       screw connectors for 230V AC
JP2       jumper for connecting GPIO15 to ground
LED_STRIP the rgb leddstrip
Q1        TIP120
Q2        TIP120
Q3        TIP120
R1        220 Ohms
R2        220 Ohms
R3        220 Ohms
S1        switch to reset ESP8266-12
SERIAL    header pins for connecting over serial
TR1       transfo
U\$1       ESP12
U1        L7812
U2        LD1117V33


I'm still unsure about what transfo to use? I was thinking about the MYRRA 44090 TRANSFORMER 1.5VA 24V. I'd like to get some feedback on this pick.

Also I'd like to gain some feedback if this scheme is safe to use. I assume the ESP8266-12 will be isolated from the net since I'm using a transfo?

For completeness I add a link here to my GitHub repo where the eagle files can be found.

• Does your board need to connect directly to mains? The most common solution is to use a 12v wall wart that already has all the necessary safety testing and approvals. – Grant Feb 21 '15 at 16:25
• A note on your schematic: Dots where wires cross or meet indicate a connection - you seem to be using the dots to indicate "no connection" - this will hopelessly confuse the netlist and board layout software when you come to lay out the PC board. – Peter Bennett Feb 21 '15 at 17:09

When rectifying an AC voltage of $x$ volt, you get a DC voltage of $x\cdot\sqrt2$ volt. That means you will need an AC voltage of $14/\sqrt2\approx10V$. With a 24V AC transformeter, you will get a very high DC voltage, about 34V, much higher than necessary. All the other Volts, 34-14=20, will need to be disippated as heat by the regulator. This is not only a waste of energy, but also may cause issues when the regulator gets overheated. A heatsink is a solution, but a transformator that gives you, say, 12V AC would be better.