LED Flash Light Badge

Are you new to Soldering and want to learn basics with a simple kit ?

If you are looking for an easy way to learn soldering or just want to make a small portable gadget, This LED Flash light badge is a great choice. This LED Flash Light Badge PCB is designed to learn the soldering .

Features:

Simple design and Low parts count
Easy to change the CR2032 battery
Quick to assembly
A personal emergency flashlight 🙂
Perfect to have for power outage

Supplies

5 mm white LED
6mm Momentary Mini Push Button Switch
10 ohm resistor
CR2032 Battery Holder and CR2032 Coin cell Battery
Custom PCB : From pcbway.com

Watch Video

Schematics:

Theory :

So… you just want to light up an LED. What resistor should you use?

LEDs have a characteristic called “forward voltage” which is often shown on the datasheets as Vf. This forward voltage is the amount of voltage “lost” in the LED when operated at a certain reference current, usually defined to be about 20 milliamps (mA), i.e., 0.020 amps (A). Vf depends primarily on the color of the LED, but actually varies a bit from LED to LED, sometimes even within the same bag of LEDs.

The V in our formula is found by subtracting the LED’s forward voltage from the voltage of the power supply.
3 V (power source) – 2.8 V (LED voltage drop) = 0.2 V In this case, we’re left with 0.2 V which we’ll plug into our V = I × R formula.

The next thing we need to know is the I, which is current we want to drive the LED at. LEDs have a maximum continuous current rating (often listed as If, or Imax on datasheets). Typical current value to aim for with a standard LED is 20 mA .

By applying ohm's law i.e V = I × R , Voltage equals current times resistance

0.2 V = 20 mA × R

or

0.2 V / 20 mA = R

There fore R=0.2 V / 20 mA = 0.2 V / 0.02 A = 10 Ω