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Hi, this is my first Instructables post, I hope you like.

My project is a simple blinking light for a bicycle helmet, the most complicated part is how to adapt the modules used to the helmet.

I don't have a perfect English, sorry if something is not understandable.

## Step 1: The Parts.

I used the next modules.

1 - Micro USB 1A 18650 Lithium Battery Charger

1 - MT3608 DC-DC Step Up Converter Booster

1 - 12v COB Led bar

1 - Switch

1 - 16850 battery (I used an old power bank)

1 - Helmet

IMPORTANT NOTE: I used transparent nail paint to make "waterproof" all the electronic circuits, and liquid silicone in the power bank's holes.

## Step 2: Electronic Part.

For this step some electronic knowledge is necessary.

This is a basic electronic circuit for two leds blinking, I replaced one of the leds for a resistance to only have one in the circuit, I tried with some values, and 1K is the best blink speed for me.

In the circuit I'm not using a resistor for the led, because I'm going to use a Dc-Dc-Step-Up to obtain 12v the necessary for my led bar, considerate this part if you try to adapt another led. (I don't check the circuit with less voltage)

I used a perforated circuit board to mount the components in the smallest space (Like 1.5cm x 2cm I forgot to take a picture and now is difficult).

## Step 3: Complete Connections of the Circuit.

In this part I explain the connections of the complete circuit. I marked with number to try to divide the circuit.

IMPORTANT NOTE: I remove the original circuit of the power bank, in its place I use the Lithium Battery Charger.

1- Connect the battery to the charger (Basic connection). The function of this module is not to allow a dangerous discharge and an overload in the battery.

2- Connect the output of the charger to the Dc-Dc-Step-Up converter, use a multimeter to measure the output voltage, manipulate the potentiometer to obtain the desired voltage.

3- Connect the output of the converter to the blinking circuit (that little green square is the representation of the circuit).

4- Connect the output of the blinking circuit to the led.

5- Enjoy your blinking lights. I'm using the led image only as reference.

## Step 4: Mounting the Circuit.

Well, now is time to mount all the components. There's no a lot to explain, because maybe your helmet is not the same that mine and you need other way to glue the components. I'm going to attach some pictures to give you an idea to how to do your project.

I used the holes of my helmet to glue the modules with double-sided adhesive tape, fortunately has the exact measure to place the modules. Only the switch was necessary to use Loctite or super glue for better result.

The COB led bar came with special adhesive.

For the power bank I printed two supports to glue them to the helmet.

And in the inside of the helmet I used liquid silicone to glue the wires.

Thank you for read it, I hope to write more.

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