Links to the bits I used

Transmitter
Shock Collar

If you need help or want to show off what you use this code for then pop over to my discord by clicking HERE

/*
Originally developed by Smouldery and Mikey who very kindly allowed us the use of their code. 

Link to Smoulderys original code: https://github.com/smouldery/shock-collar-control/blob/master/Arduino%20Modules/transmitter_vars.ino

adapted by Deviant Designs
*/


byte buttonPin = 9;

//=================================================== START OF COLLAR SETUP CODE ======================================================================

//const int shock_min = 0; // Minimum of power a command will be executed at
const int shock_delay = 10; // Maximum rate at which the shock function can be used at
//const int cmd_max = 1000; // Maximum of milliseconds which a command can be executed at

// Constant variables
const int pin_led = LED_BUILTIN; // Pin for indication LED
const int pin_rtx =  14; // Pin to transmit over
const String key = "00101100101001010"; // Key of the transmitter, dont touch if you dont know how it works

// Variables which do change
int collar_chan = 0; // Can be channel 0 or 1
int collar_duration = 500; // Duration of the command in milliseconds
int collar_power = 10; // Strength of the command, can be 0-100, but will be limited by shock_min and shock_max

// Define values for easier recognition
#define COLLAR_LED 1
#define COLLAR_BEEP 2
#define COLLAR_VIB 3
#define COLLAR_ZAP 4

// Strings used for building up the command sequence
String sequence, power, channelnorm, channelinv, modenorm, modeinv;

// Store the last time anything was transmitted to the collar
unsigned long transmit_last = 0;
unsigned long shock_last = 0;
void transmit_command(int c, int m, int p = 0)
{
  transmit_last = millis();
  switch (c) // Check the channel
  {
    case 1: // Channel 1
      channelnorm = "111";
      channelinv = "000";
      break;
    default: // Channel 0
      channelnorm = "000";
      channelinv = "111";
      break;
  }

  switch (m) // Check the mode
  {
    case 1: // Light
      modenorm = "1000";
      modeinv = "1110";
      break;
    case 2: // Beep
      modenorm = "0100";
      modeinv = "1101";
      break;
    case 4: // Shock
      modenorm = "0001";
      modeinv = "0111";
      shock_last = millis();
      break;
    default: // Vibrate
      modenorm = "0010";
      modeinv = "1011";
//      p = 10; // Set strengh to 10 for the command to be executed properly
      break;
  }

  // Convert power to binary
  int zeros = String(p, BIN).length();

  String power;
  for (int i = 0; i < 7 - zeros; i++)
  {
    power = power + "0";
  }
  power = power + String(p, BIN);

  String sequence = "1" + channelnorm + modenorm + key + power + modeinv + channelinv + "00";

  digitalWrite(pin_led, LOW);
//  d = constrain(d, 50, cmd_max); // Clamp duration of the command
  unsigned long cmd_start = millis();
//  while (millis() - cmd_start < d)
//  {
    // start bit
    digitalWrite(pin_rtx, HIGH);
    delayMicroseconds(1500); // wait 1500 uS
    digitalWrite(pin_rtx, LOW);
    delayMicroseconds(741);// wait 741 uS

    for (int n = 0; n < 41 ; n++)
    {
      if (sequence.charAt(n) == '1') // Transmit a one
      {
        digitalWrite(pin_rtx, HIGH);
        delayMicroseconds(741);
        digitalWrite(pin_rtx, LOW);
        delayMicroseconds(247);
      }
      else // Transmit a zero
      {
        digitalWrite(pin_rtx, HIGH);
        delayMicroseconds(247);
        digitalWrite(pin_rtx, LOW);
        delayMicroseconds(741);
      }
    }
    delayMicroseconds(4500);
//  }
  digitalWrite(pin_led, HIGH);
}

void collar_keepalive()
{
  if (millis() - transmit_last >= 120000) // Send command to the collar at least every 2 minutes to make it stay on
  {
    Serial.println("Keep-alive:\tCollar");
    transmit_command(collar_chan, COLLAR_LED, 50);
  }
}

//=================================================== END OF COLLAR SETUP CODE ======================================================================

void setup()
{
//=================================================== START OF COLLAR SETUP CODE ======================================================================
  pinMode(pin_rtx, OUTPUT); // Set transmitter pin as output
  pinMode(pin_led, OUTPUT); // Set LED pin as output
  Serial.begin(115200);
  //=================================================== END OF COLLAR SETUP CODE ======================================================================
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop()
{
	collar_keepalive();
 
	if (digitalRead(buttonPin) == LOW) {
    transmit_command(collar_chan, COLLAR_VIB, 100);
  }
}