Sequential Turn Lights Driver

Four-LED left and right sequence

Particularly suited to motorcycles

Circuit diagram:

Sequential Turn Lights Driver


R1_____________500K  1/2W Trimmer Cermet or Carbon
R2______________47K  1/4W Resistor
R3,R4____________1K  1/4W Resistors
R5,R6,R7,R8_____10K  1/4W Resistors

C1_______________1µF  63V Polyester or electrolytic capacitor
C2_____________220µF  25V Electrolytic capacitor

D1-D8__________LEDs Yellow ultra-bright types

Q1,Q2,Q3,Q4___BC337   45V 800mA NPN Transistors

IC1____________7555 or TS555CN or TLC555CP CMos Timer IC 
IC2____________4017 Decade counter with 10 decoded outputs IC

SW1____________Vehicle Turn Lights switch (See Comments)

Battery_________12V Vehicle battery


This device was designed on request and allows sequential operation of four Leds either to left or right direction, obtained by means of a 7555 CMos timer IC (IC1) wired as an astable multivibrator driving a Decade counter (IC2). This IC is set to count a sequence of four by connection of pin #10 to pin #15, but any sequence count in the 2-10 range can be set by choosing the appropriate pin connection. Obviously, LEDs, Transistors and their respective Base-limiting resistors must also be added or omitted accordingly.
R1 is a variable resistor (Trimmer), used to set the desired speed of the LEDs. SW1 is a change-over switch that should already exist in your motorcycle, having a center-off position and Turn-left and Turn-right positions.
D1, D3, D5 and D7 are the Turn-left LEDs; D2, D4, D6 and D8 are the Turn-right LEDs.

For a motorcycle they are arranged on a single board about 20 - 25 cm wide as shown in the image below. The outer red LEDs are the tail/brake lights and can be driven by a circuit like the LED driven tail/brake Light Cluster available on this website.

Sequential Turn Lights example