LED Strobe Kit Tutorial

This month we wanted to get a little flashy. Nothing worse that seeing blue lights behind you while driving, right? For this month, we designed a small red and blue LED strobe kit, that should scale closely to be able to be installed on those LEGO vehicles some of us still build!

 

To purchase this kit, click here
Red / Blue Strobe Kit



First, you should refresh yourself on soldering safety!

WARNING: SOLDERING IRONS ARE HOT.  SOLDERING IRONS ARE NOT TOYS.  ALWAYS WEAR EYE PROTECTION WHILE USING A SOLDERING IRON.


555 Timer → We used two 555 timers in this kit to provide the strobe effect. Each timer handles the pulsing of the LEDs attached to it. One 555 timer will be LOW while the other will be HIGH.

Resistors → The resistors in this kit provide current limiting to the LEDs as well as setting up the timer interval across the 555 timers.

LEDs → The five red LEDs are all connected in parallel and the five blue LEDs are also all connected in parallel. They are connected backwards to each other so only one side will light up at a given time depending on current flow.

For your reference, here is a copy of the resistor color code.  The resistors in this kit use the 4-Band Code.
Resistor Color Code

Preparation

Count all of your parts and verify everything is in your kit.

Item
Quantity
Description
555 Timer
2
8 Pin IC
8 Pin Socket
2
8 Pin IC Socket
470 Ohm Resistor
2
Yellow Violet Brown
68k Ohm Resistor
2
Blue Gray Orange
0.1uF Capacitor
1
Yellow/Orange Dome (104)
2.2uF Electrolytic Capacitor
1
Black and Silver Can Shaped
Red LED
5
Red Dome - Long Leg is Positive
Blue LED
5
Blue Dome - Long Leg is Positive
Battery Harness
1
Red and Black Wiring
9V Battery
1
Battery
PCB
1
Printed Circuit Board


Step 1

Locate the two 68k Ohm Resistors and install them in positions R1 and R2. Bend the legs slightly outward will help hold them in place while you solder.

Step 2

Locate the two 470 ohm resistors and install them into locations R3 and R4.

Step 3

Next we will take the two 8 pin sockets, and place them into IC1 and IC2. Be sure that the notch on the sockets match the silk screen on the PCB.



Step 4

Install the 2.2uF Electrolytic Capacitor at location C1. Be sure that the white strip is aligned with the white strip next to the C1 designation. This component must be installed in the correct orientation to work correctly.



Step 5

Find the 0.1uF capacitor, and install it into location C2. It does not matter which pin goes in which hole as this is a ceramic capacitor.



Step 6

Separate the LEDs based on color. The RED LEDs will be installed at locations LED1, LED2, LED3, LED4, and LED5. The BLUE LEDs will be install at locations LED6, LED7, LED8, LED9, and LED10. LEDs must be installed in the correct orientation. The long leg will go into the round pad, and the short leg will go into the square pad.



Step 7

Solder the Red and Black 9V Battery Wire to the BATTERY location. Be sure that RED goes to the + and BLACK goes to the -. You can install the wire from either side. We prefer installing from the bottom as it is cleaner.

Step 8

Install both 555 Timers, making sure that the notch on the IC aligns with the notch on the PCB. Push them all the way in until they are seated, you may hear a click to know they are all the way in. Connect the battery to the header, and your kit should now strobe between the Red and Blue LEDs.



Schematic of the Kit

Red and Blue Light Strobe Schematic