Higher quality tesla coil interrupter arduino code

//Warning! THIS CODE WILL HEAT UP YOUR TESLA COIL VERY QUICKLY!!! USE IT AT YOUR OWN RISK!!!
int duty;
int raw;
int state = 0;
void setup(){
  TCCR1B = 0x01;//sets frequency to 32khz

// ADC Boost Start - sets ADC clock to 1MHz
// defines for setting and clearing register bits

#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif

// set ADC prescaler to 16
  sbi(ADCSRA,ADPS2) ;
  cbi(ADCSRA,ADPS1) ;
  cbi(ADCSRA,ADPS0) ;
// ADC Boost End

}

void loop(){
  raw = analogRead (3);
  //limit maximum power
  if (raw > 40){
    raw =40;
  }
  //reduces frequency from 32khz to 16khz
  if (state == 0){
    state =1;
  }else{
    state = 0;
    raw = 0;
  }
  //creates the pwm signal
  duty = raw/8;
  analogWrite(9, duty);

}