Sequential brake/turn signal

Circuit diagram:

Component:

R1, R5____________1K 1/4W resistors

R2______________33K 1/4W resistor

R3_____________100K 1/2W Fine-tuning Ceramic Potentiometer

R4_______________1M 1/4W resistor

R6, R7, R8 ________ 10K 1/4W resistors

R9______________4K7 1/4W resistor

R10_____________33R 1/4W resistor (see note)

C1_______________1µF 63V Polyester Capacitor

C2_____________100nF 63V Polyester Capacitor

C3_____________470µF 25V electrolytic capacitor

D1______________LED (any size, shape, or color)

D2, D3________1N4002 100V 1A diode

D4--D15________LEDs High-brightness, high-efficiency red type (see note)

Q1___________2N3819 General Purpose N-Channel FET

Q2____________BC337 45V 800mA NPN transistor

Q3____________BC547 45V 100mA NPN transistor

IC1____________7555 or TS555CN CMOS timer integrated circuit

IC2, IC3________4094 8-stage shift memory bus register integrated circuit

SW1____________SPST Brake/Turn Signal Switch

Comment:

The circuit is designed to allow up to 16 LED clusters to illuminate sequentially in a bar pattern. The LED sequence begins when the brake pedal is pressed (or the turn signal switch is turned on), and all LED clusters remain lit when the last cluster illuminates, until the brake pedal is released or the turn signal switch is turned off.

Note:

- R5 and D1 are optional: they may be used for monitoring when setting the sequence frequency via R3.

- A cluster can consist of up to 12 LEDs, as shown on the right side of the circuit diagram. Common cluster types typically range from 5 to 10 LEDs.

- Up to 16 such cluster driver circuits can be built, each consisting of an LED, two transistors and three resistors, and can be connected to the progressively numbered outputs of IC2 (the first eight clusters) and IC3 (the remaining clusters).

- If the required number of clusters is a maximum of 8, IC3 can be omitted.

- The constant output current value of the LED can be adjusted by changing R10.

 The formula is: R = 0.6/I (I is expressed in amperes).

- Use a high-brightness, high-efficiency red LED of the appropriate size, and adjust the R10 value to fit the absolute maximum rating of the LED.

- The main circuit consists of three integrated circuits and related components, permanently connected to the power supply (and D1 will flash), but its 12V positive power supply can be connected to the car's main switch, or a switch can be added.