Led Knight Rider Circuit

Knight Rider Circuit

This circuit mimics the lights in knight rider's car. They flash one at a time chasing each other.

Overview

In the Knight Rider circuit, the 555 is wired as an oscillator. It can be adjusted to give the desired speed for the display. The output of the 555 is directly connected to the input of a Johnson Counter (CD 4017). The input of the counter is called the CLOCK line.
The 10 outputs Q₀ to Q₉ become active, one at a time, on the rising edge of the waveform from the 555. Each output can deliver about 20mA but a LED should not be connected to the output without a current-limiting resistor (330R in the circuit above).
The first 6 outputs of the chip are connected directly to the 6 LEDs and these "move" across the display. The next 4 outputs move the effect in the opposite direction and the cycle repeats. The animation above shows how the effect appears on the display.
Using six 3mm LEDs, the display can be placed in the front of a model car to give a very realistic effect. The same outputs can be taken to driver transistors to produce a larger version of the display.

In the Knight Rider circuit, the 555 is wired as an oscillator (Astable mode). The output of the 555 is directly connected to the input of a 4017 decade counter.

The input of the 4017 counter is called the CLOCK line. The 10 outputs Q₀ to Q₉ become active, one at a time, on the rising edge of the waveform from the 555.

IC 555 data sheet

555 Timer Internal Circuit Block Diagram

 

 

555 Timer Internal Circuit Block Diagram

 

See the Datasheet for the LM555 for more information and example applications/circuits.
The output of a 555 timer is either high (close to +V_CC) or low (close to GND).
Inside the 555 timer is a voltage divider the divides +V_CC into thirds. A voltage comparator compares the trigger input (pin 2) with 1/3 V_CC, and another comparator compares the threshold (pin 6) with 2/3 V_CC. The point at 2/3 V_CC on the voltage divider is connected to the control voltage (pin 5). This pin can be used to modify the values of 1/3 V_CC and 2/3 V_CC without having to change V_CC. However, if this input is not going to be used, it should be grounded through a bypass capacitor (0.01uF) to protect it from noise.
The 555 timer also has a flip-flop, which is controlled by the two comparators and the reset input.
The trigger and reset inputs are level-sensitive active low inputs. To activate the trigger, the voltage on the trigger pin must be pulled down to under 1/3 V_CC. The trigger experiences a delay when changing states so it should be returned to high at least 10μs before the end of the timing cycle or else the cycle will be immediately re-triggered.
To reset the timer, the voltage on the reset pin must be pulled under 0.4V. The reset input will override other inputs and set the output (pin 3) to low. If the reset input is not going to be used, it should be wired to V_CC to prevent false signals.
In its initial state (assuming threshold is low and trigger is high), the 555 timer's internal flip-flop connects the discharge (pin 7) to the ground and sets the output to low. Each time the trigger voltage is pulled down under 1/3 V_CC, the flip-flop will break the discharge pin's connection to ground, and set the output to high. It will hold this state until something (usually a capacitor) forces the threshold pin's voltage equal to 2/3 V_CC, which will reset the flip-flop.

555 Pins

Monostable and Astable mode

The 555 family of timer chips can be used in either monostable mode or astable mode. In the monostable or "one shot" mode, each time the 555 timer is triggered, the output will go high for a specified amount of time, then return to low and await another trigger signal. In the astable mode, the timer triggers itself periodically and becomes an oscillator, sending out a train of pulses.  

Monostable Mode

Connections for the 555 timer in monostable mode:  

The circuit operates as follows:

1. In this circuit's initial condition, the capacitor C is held discharged through the discharge pin, which is grounded through the flip-flop in the timer. The threshold voltage is equal to the voltage across the capacitor.
2. When the trigger pin receives a negative trigger pulse less than 1/3 V_CC, the flip-flop sets the output to high and disconnects the discharge pin from the ground. This allows the capacitor to charge until the voltage across it reaches 2/3 V_CC, which takes about t=1.1R_AC seconds.
3. When the threshold voltage reaches 2/3 V_CC, the flip-flop resets, connecting discharge to the ground and setting output to low. It is now back in the initial state, and awaits another trigger pulse. 

By selecting the resistor and capacitor, the length of the output pulse can be controlled.

 Timing diagram for the 555 in monostable mode:

 Astable mode

astable mode, the circuit will keep re-triggering itself, resulting in a pulse train. The circuit for the 555 in astable mode looks like this: 

 

the capacitor charges and discharges between 1/3 V_CC and 2/3 V_CC. The 555's output will the high while charging, and low while discharging. The capacitor charges and discharge at different rate—it has to charge through R_A and R_B, but it only discharges through R_B. Thus, we can adjust the length of the output's highs and lows by adjusting these resistors.
The length of a output high is equal to:

The timing diagram for the 555 in astable mode:

555 applications

single 555 for flashing the display cursor.

4017 IC Datasheet

4017 IC is a CMOS counter/divider integrated circuit, actually a decada counter with 10 decode ouputs. It is 5 stage Johnson counters having 10 decoded outputs. Inputs include a clock, a reset, and a clock inhibit signal.  

 Description

 The CD4017BC is a 5-stage divide-by-10 Johnson counter with 10 decoded outputs and a carry out bit.
The CD4022BC is a 4-stage divide-by-8 Johnson counter with 8 decoded outputs and a carry-out bit.
These counters are cleared to their zero count by a logical “1” on their reset line. These counters are advanced on the positive edge of the clock signal when the clock enable signal is in the logical “0” state.
The configuration of the CD4017BC and CD4022BC permits medium speed operation and assures a hazard free counting sequence. The 10/8 decoded outputs are normally in the logical “0” state and go to the logical “1” state only at their respective time slot. Each decoded output remains high for 1 full clock cycle.The carry-out signal completes a full cycle for every 10/8 clock input cycles and is used as a ripple carry signal to any succeeding stages 

  

Features

Wide supply voltage range: 3.0V to 15V 

High noise immunity: 0.45 VDD (typ.) 

Low power Fan out of 2 driving 74L TTL compatibility: or 1 driving 74LS 

Medium speed operation: 5.0 MHz (typ.) with 10V VDD

Low power: 10 mW (typ.)

Fully static operation

Applications

  

 • Automotive
• Instrumentation
• Medical electronics
• Alarm systems
• Industrial electronics
• Remote metering

Pin Diagrams

 Functional diagram

Logic diagram

Timing diagram

 

 

 

 

 

 

LED Light Bar 5050 smd

Introduction

LED Light Bars are a super-easy way to add some extra-bright and colorful illumination to your project. Each Light Bar is essentially a set of three super-bright 5050-size LEDs. They’re offered in a variety of colors including white, red, blue, and green (note: the blue and green light bars are an older version, they

look different but can still be connected the same way).

 While these bars are very simple devices, they do have a few quirks when it comes to using them. Like the fact that their nominal operating voltage is 12V. In this tutorial we’ll go over some of the important specifications of these LED Light Bars.

Hardware Overview

A glance at the LED Bars will reveal that there’s not a whole lot required to interface with them. There are two pairs of wire pigtails coming off the sides, labeled ‘+’ and ‘-’. The darker-gray wire connects to the ‘+’ pin, and the white wire connects to ‘-’ on both sides.

 These wires supply power directly to the LEDs. A nominal voltage of 12V should be applied to these wires. A lower voltage will work (to a point) but result in dimmer LEDs. Either of the wire pairs can be used to supply power to the LED, and the unused pair can either be trimmed or connected to another LED bar.

For mounting purposes there are drill holes on either side of the board, and a peel-away sticky foam on the backside.

LED Characteristics

The “nominal” voltage for these LED Bars is 12V. “Nominal” as in that’s what’s recommended by the manufacturer. They will work at lower voltages, although that’ll mean sacrificing some brightness.
The table below shows some of the characteristics for each of the LED bar colors. These are values we found while testing the bars out. The minimum voltage was the lowest voltage where the LEDs were at recognizably lit up, although very dim. We recommend that you at least give the LEDs around 7V. The higher the voltage, the brighter your LED will be.

As far as current pull goes, both LED colors consume about the same when powered from between 9 and 12V, up to about 55mA when powered at the nominal voltage.

Light Bar Circuit

Looking at the visible components on the bars, it’s apparent that there’s not a lot to them. Three six-pin, SMD LEDs, and an equal number of resistors. We can easily reverse-engineer this circuit to find out exactly how these things work.

Each SMD LED is actually a collection of three equal LEDs. The LED bar’s PCB is set up to string those LEDs in series, with the resistor in-line to limit current. The values of the resistors depend on the color of the Bar. The red bar, for example uses 330Ω,301Ω,151Ω,241Ω and the white bar uses 150Ω resistors.

Connect three of those circuits in parallel an you have your LED bar!

Assembly tips

In most cases, Light Bar assembly begins with stripping some wire. The wire pigtails on the bars are 20 AWG, and should be easy enough to strip with any, old wire stripper.
The wire lengths can be extended, if need be, with a little splice. Don’t forget to cover your splice with heatshrink!
Alternatively the stripped pigtails can be tinned, crimped, or plugged directly into a mating connector.

Stringing bars

The ‘+’ and ‘-’ wires of one bar can be connected to another to string them together. More and more bars can be stringed until you start to approach the current limit of the 20 AWG wires – about 1.5A. With some back of the napkin calculations – 55mA per bar, 1.5A max – that’d be 25-ish bars.

Mounting the bars

There are two possible methods for mounting the LED bars. There are mounting holes on either end of the bar with a 0.15" drill diameter, allowing for the bars to be screwed down. Every bar also includes a peel-away sticky-foam backing which adheres about as well as you could expect.
With a little prying, the PCB assembly part of the LED bar can be removed from the plastic mounting backing. This might be useful if your boards might need a tighter fit.

Example Circuits

 There are a variety of ways these LED bars can be controlled and illuminated. Let’s look at a few example circuits:

Direct Power

If you don’t care about dimming the LEDs, the easiest way to power them up is to connect them directly to a 12V power supply. Stick them in your enclosure or project, plug the supply in, and forget about them. If you’re looking for a supply that can source 12V,

The DC Terminal Adapter makes connecting the 12V wall wart to the LED bar way easy.

To gain a little control over the LEDs, you can add a switch in-line between the power source and either the ‘+’ or ‘-’ wire of the first LED bar.

 

Dimming with MOSFET Using a 555 Timer

If you want to add some dimming control over your LED bar, MOSFETs combined with pulse width modulation are the tools you’ll need. There are a few approaches you can take to generating a PWM signal to control the MOSFET and LED bar. Here are a couple options: 

control the LED bars via PWM. Use a circuit like below, with an n-channel MOSFET  use a 555 timer and a handful of common components to generate the PWM signal. Here’s an example circuit:

 Most 555 timers can work at up to 16V, so you can run it directly off the 12V supply. Then twist the potentiometer to adjust the brightness.

LED Light bar applications

 

 

 

 Application: 
                   === > Led module + back light for sign

                   === > Back lighting for advertising signs,channel letters,light boxes,etc.
                   === > Widely used indoor/outdoor advertising sign, channel letter & signs with non-waterproof requirements

                   === > Ideal for small channel letter & lighting box

 

 Specifications:

 

Led type	5050smd
Led quantity	3pcs
Size	75*12*4mm
Material	Plastic

Input voltage	DC12V
Current	60mA
Power	0.72W
Color	Red/Blue/Green/White/RGB
Viewing angle	120°
Lumen	60-66lm
Working temperature	-20℃--60℃
Storing temperature	-25℃--80℃
Certification	CE/Rohs

 Lighting pictures:

Installation Instruction:

LED Polarity :

smd led strip

 Led data sheet

                            
Forwatd Voltage            =    2.8 ~ 3.5 DC

Forward Current            =     60 mA

Lumens / LED                =    18.5 ~ 22.5 Lumens

Beam Angle (Degrees)    =    120

Power                             =  0.2 w