A few days ago I bought a three-color tower light with buzzer for visual and audible alerts. And because I’m a big kid, I thought to build as the first application a game of lights in the style of a police car. The result will be seen at the bottom of this article.

Before entering into the connection and programming area, I give you some details about the product. The tower light has three colors and a buzzer. The tower can be easily controlled by an Arduino board, four N-channel MOSFETs or NPN transistors, and four resistors.

The light tower is branded Adafruit and produced in China. At least this is written on the product that I use in this tutorial. Also, there is a schema somewhere on it with Chinese letters. Thank you Adafruit!

Everywhere I’ve been looking for information about how it works and how I can control it, I’ve given this tutorial. The tutorial is dedicated to the RGB LED strips and less to a light tower. Generally, Adafruit produces good tutorials, so I think that I don’t have to make a great effort to turn ON the lights. But this time I was a bit misguided by the schema with connections found in the tutorial. For the NPN Bipolar Transistors (PN2222), I recommend you carefully look how the three pins of the transistor are located or use the schema from this article. When I connected the light tower just like in the Adafruit’s tutorial (the NPN schema), the result was a tower light that just makes some noise and has two lights on. Obviously, the pins of the transistors were wrongly connected.

Let’s get to the practical side.

Components:

• 1 X Tower Light – Red Yellow Green Alert Light & Buzzer (I buy it from here, but you can buy it also from Amazon)
• 4 X NPN Bipolar Transistors (PN2222) (link on Amazon)
• 4 X 100-220 Ohm resistors (link on Amazon)
• 1 X Arduino board (I think you already have one, but in case I’m wrong, you can take one from here)
• some wires (link on Amazon)

The schema:

Tower light and Arduino Schema

The Arduino code:

//Constants
#define REDPIN 9
#define YELLOWPIN 10
#define GREENPIN 11
#define BUZZ 12

//Variables
int  ledDelay=50;
long previousMillisLights = 0;    
long intervalLights = 500;   
long previousMillisTemperature = 0;    
long intervalTemperature = 1000;  

void setup()
{   
    Serial.begin(9600);
    pinMode(REDPIN, OUTPUT);
    pinMode(YELLOWPIN, OUTPUT);
    pinMode(GREENPIN, OUTPUT);
    pinMode(BUZZ, OUTPUT);

}

void loop()
{
 unsigned long currentMillis = millis();
   
    if ((unsigned long)(currentMillis - previousMillisLights) >= intervalLights) {
    redPoliceLights();
    yellowPoliceLights();
    greenPoliceLights();
  //add here the code if you want the turn on the buzzer
 //analogWrite(BUZZ, HIGH);
   intervalLights = currentMillis;
   }
  }

//turn ON and OFF the red light
void redPoliceLights(){
   analogWrite(REDPIN, HIGH);
   delay(ledDelay);
   analogWrite(REDPIN, LOW);
   delay(ledDelay);
   analogWrite(REDPIN, HIGH);
   delay(ledDelay);
   analogWrite(REDPIN, LOW);
   delay(ledDelay);
   analogWrite(REDPIN, HIGH);
   delay(ledDelay);
   analogWrite(REDPIN, LOW);
   delay(ledDelay);
  }

//turn ON and OFF the yellow light
void yellowPoliceLights(){
   analogWrite(YELLOWPIN, HIGH);
   delay(ledDelay);
   analogWrite(YELLOWPIN, LOW);
   delay(ledDelay);
   analogWrite(YELLOWPIN, HIGH);
   delay(ledDelay);
   analogWrite(YELLOWPIN, LOW);
   delay(ledDelay);
   analogWrite(YELLOWPIN, HIGH);
   delay(ledDelay);
   analogWrite(YELLOWPIN, LOW);
   delay(ledDelay);
  }

//turn ON and OFF the green light
  void greenPoliceLights(){
   analogWrite(GREENPIN, HIGH);
   delay(ledDelay);
   analogWrite(GREENPIN, LOW);
   delay(ledDelay);
   analogWrite(GREENPIN, HIGH);
   delay(ledDelay);
   analogWrite(GREENPIN, LOW);
   delay(ledDelay);
   analogWrite(GREENPIN, HIGH);
   delay(ledDelay);
   analogWrite(GREENPIN, LOW);
   delay(ledDelay);
  }

Tower Light Demo: