LED Bar Mode Chaser/Scanner Circuit [Mustang Style]

When we look at the main functions of the Mustang LED scanner circuit we have proposed we can break it down into two main features which we will describe in detail below:

Function One: The Bar Mode Illumination

First we have this interesting effect wherein the LEDs light up in a bar mode style. Here, the LEDs start illuminating from both ends of the strip and gradually move toward the center creating a bright and vibrant glow which lights up the entire module.

As soon as this dazzling display reaches its peak at the center then the next step kicks in. The LEDs begin to turn off in the same sequence they lit up, starting from those outermost ends and working their way inward until every single LED has switched OFF.

What is even better is that we can tweak the speed of this whole process! We have a potentiometer that allows us to adjust how fast or slow these actions happen so everyone can set it according to their personal taste.

Function Two: The Simultaneous Shutdown

Now moving on to our second scanning sequence, it is quite similar to the first one but with a twist. Instead of having each LED turn off one by one, this time we get to see all the LEDs shut off at once. Imagine that sudden darkness after such a bright display, it adds an exciting element to our circuit.

Implementation

Now if we are talking about how we can bring these two fantastic functions to life, it is pretty straightforward. We can easily implement this design through a couple of 74LS164 ICs along with a 555 IC oscillator. If you take a look at the circuit diagram we have provided next, you will see how everything fits together seamlessly.

Circuit Diagram

Using IC 74LS164 as the Controller

In the Mustang scanner LED light circuit that we are discussing, we utilize a couple of 8-bit parallel-out shift register integrated circuits (ICs) known as the 74LS164. These ICs are driven by an IC555 which we have configured to function as our clock oscillator.

To help us understand how this circuit operates, we can look at it through the lens of two distinct modes in the design:

Mode 1: The Sequencing LED Bar Effect

As we can see in the circuit diagram above, there is a 3-pole, 9-throw switch that serves as our changeover switch. This switch allows us to imitate the two functions we described earlier.

In Mode 1 we connect switch S1 just as shown in the circuit diagram.

In this position, the LEDs illuminate in a beautiful sequencing bar-like fashion with each rising edge of the clock pulses generated by the IC555. This continues until all the LEDs are glowing brightly.

When the final "high" signal reaches pin 16 then transistor T1 momentarily resets both of our ICs resulting in an instant shutdown of all the LEDs at once.

When we build the actual prototype it is important to arrange the LEDs from outputs Q9 to Q16 so that Q16 is facing Q8 while Q9 is positioned at the outer end of the relevant strip.

When this sequence occurs then a fresh new cycle begins and it keeps repeating for as long as we do not change the position of S1.

Mode 2: The Instantaneous Shutdown

Now let us move on to Mode 2. In this mode we connect switch S1 to the positive supply. This means that S1a connects with the +5V line, S1b connects to the collector of T1 and S1c connects with resistor R5.

Additionally we connect reset pins 9 of both IC1 and IC2 to the collector of T1 whose base is configured with the last output Q16 from IC2.

When we turn on the power switch then we see that the LEDs start illuminating in that same bar-like mode as before—from Q1 to Q8 and then from Q9 toward Q16—responding to each clock pulse supplied by our astable IC555 at pin 8 of both 74LS164 ICs.

Now here comes an exciting part, as soon as a high signal reaches pin 16 across those shifting outputs then T1 instantly inverts and sends a low signal to serial pins 1 and 2 of our ICs.

This causes the LEDs to begin shutting off one by one across their arrays in the same sequence they illuminated in response to each clock pulse from IC555.

The LED Sequence Keeps Recycling

This entire procedure keeps repeating for as long as we do not change the position of switch S1 from its current setting.

Overall these two functions are pretty straightforward to implement and we can have our LEDs scanning across the whole array just like how an actual Mustang scanner is supposed to operate!