Learning how to assemble the Keychain
Let's go through all the components of the Keychain Flashlight
Tools you'll need
On the back of the Flashlight PCB you'll find a big silver circle marked with BT1. Take your Battery Holder component with the open side facing towards the bottom of the PCB. Place it through the two hole beside the big silver circle. Once in place flip the PCB over to the front and solder the two leads.
Staying on the front of the board take your 6mm Tactile Button and place it through the holes around SW1. Once in place flip the PCB over to the back and solder the four leads.
LEDs have polarity, which means that they only allow current in one direction. We must make sure to place them in the correct orientation. One leg of the LED is longer than the other, this is the positive leg. It will go into the circle hole. While the other shorter leg will go into the square hole.
Place all an LED through the front and into the LED1 holes then bend it towards the top of the board. Repeat this for all 3 LEDs and then flip to the back and solder all the leads.
The Battery like the LEDs has polarity. It has a smooth smooth that is positive and a negative rough side.
With the back of the board facing up slide the Battery into the holder with it's smooth positive side also facing up.
Congrats! You should now have a Keychain Flashlight. If it doesn't light up when pressed maker sure your battery is in the right way. Double check the orientation of your LEDs. Remember that if you touch up any solder joints to take the battery out.