Introduction: "I Think of You" Heart of Valentine's Day

In this article I will show you how to make glow a connected heart, which can be activated anywhere, when you thinking about your love

Step 1: Materials Required

Materials required :

1* ESP32

1* Polulu 5V Step-Up/Step-Down Voltage Regulator S9V11F5

1 * 12.6V Battery pack : composed of : 3* 18650 battery in series, 1* li-po 3S BMS

348 * Red LED 5mm

4* 2n2222 npn transistors

4* 260Ω resistors

1* 330Ω resistor

Prototype PCB, large enough to fit the dimensions plus some space for the transistors and connectors

-3D printed Heart case Front/Back

Lots of thin wires (AWG30)

- Some connectors , female header , jst plug ..

Step 2: Schematic

The circuit is composed of 348 red leds divided into 7 series and 49 parallels controlled by 4 transistors; we use the voltage drop of the leds (1.75V ~) to avoid having to put additional resistors (except at the end of one series made up of 5 leds instead of 7).

The heart is divided into 4 independently controllable zones allowing additional lighting effects.

Step 3: Heart Box 3D Design

Heart measures approximately 5.9 inches wide by 5.12 inches high, and 2 inches deep, suitable for almost all 3D printer3.

The perforated face at the front allows the leds to be placed without them falling, and to allow them to be soldered easily.

Step 4: Soldering & Assembly of the Heart

Now the challenge will be to install and solder the 348 LEDS; following the color scheme, place the leds without connecting the negative (-) ends of each zone; they must be connected to the collector of the four transistors, and each positive pole (+) must be directly connected to the pole (+) of the battery.

For the battery pack assembly, you will need to connect the three 18650s in series, and connect each cell (+) to the BMS ; then solder a jst connector at the output.

Step 5: Assembly of the ESP32

First, connect the input of the battery pack to the Vin input of the voltage regulator; GND pin to battery and ESP GND ; Vout pin of the regulator on Vin of the ESP

The Emitter pin of the transistors to the GND; the Base pin with a resistor and outputs D26, D15, D4 and D2 of the ESP;

all the Anode (+) LEDs must be connected all together to the positive pin of the battery pack (12.6V) ; the Cathode of the leds (-) must be connected for each assembly (see the colored scheme) to the collector pin of the transistors

Step 6: Arduino Program & Web Interface

It's a basic program used to control the output of transistors with a Wifi connection, first enter your SSID and the password of your Wifi network

In the rest of the program we will define the control output of the leds of each colored zone.

We use four pwm outputs to create variable light intensity (glowing effects).

Connect your ESP and upload the program ; once done the ESP will create a web page, to retrieve the IP of the web interface, open the serial monitor once the program has uploaded and note the address displayed.

In this example I use a button to turn on all the leds and a button for debugging.

Finally, to be able to access this local web page from anywhere, you must do a port forwarding; depending on your internet provider, the process is different.

Step 7: Make It Glow !

On the video you can see the heart shining after pressing the button on the web page

(And some glitch with leds that stay on)

Make it Glow Contest

Participated in the
Make it Glow Contest