IR Based Home Automation

We are operating the home appliances by using an IR remote which is interfaced with the microcontroller by using various components.

            A 12v power supply is generated and it is supplied to the micro controller by using a transformer. Atmel microcontroller based hardware is used along with real time clock interface. The development involves writing the software code for microcontroller at which the automation can be done. The microcontroller based hardware is chosen to implement this concept. The loads like lights, motors, heaters, power controlling system and also current through the loads can be controlled in this project. We can control all loads at a time from one place (control room) without connecting any physical wire between loads and control room.

Since AC loads are also controlled in this project and the microcontroller cannot handle AC loads, TRIAC is used to control the AC loads. The speed of AC motor can be varied rapidly on and off by TRIAC. The main advantage of using a TRIAC to vary the speed of an AC motor is the TRIAC reduces the energy flow to the motor and TRIAC works very well for alternating currents. Hence, in our module we use the TSOP 1738 IR receiver, MOC 3021 TRIAC, IR remote controller, crystal oscillator and some other related equipment. Crystal oscillator is used to generate a frequency of 11.0592MHz. Two load capacitors of 33 pF are used to eliminate the noise which is occurred in the oscillator. For reset button we used one pull up switch which is connected to reset pin of micro controller. An IR remote control device uses IR light which is invisible light about 950nm wavelength. One biggest problem in using IR light is that there many other sources of it like sun, light bulbs, fire. In order to exclude other sources, IR signal is modulated by some frequency. Receiver has to be tuned for this frequency. Mostly remote controls transmit IR signal using 36 kHz frequency signals. Here in our module we are using TSOP1738 IR receiver which generates the frequency of 38 kHz, exactly matched with our remote controller.

            Thus, we can control (i.e., switch on/off) the home appliances by using an IR remote which is interfaced with microcontroller.

CODE:

#include <REG8051.H> sbit load1 = P1^7; sbit load2 = P1^6; sbit load3 = P1^5; sbit load4 = P1^4; sbit load5 = P1^2; sbit fan = P3^7; sbit ir=P3^2; sbit led=P3^4; bit cc1,cc,a,fanon,l1,l2,l3,l4,l5,l6,power; unsigned char speed,ledblink=0; unsigned char key,key1,count=1; void irs(void) interrupt 0 using 0 { EX0=0; TL0=0x29; TH0=0XFa; count=1; ET0=1; TR0=1; } void time(void) interrupt 1 using 1 { TR0=0; count=count+1; if(count==3) //check bit cc=ir; if(cc1!=cc) { if((count>8)&&(count<15)) { a=ir; key=key<<1; key=key|a; } if(count==14) { key1=key; cc1=cc; key=0xff; } } if(count<65) { if(ledblink==1) led=~led; TL0=0x29; TH0=0XFa; TR0=1; } else { ET0=0; led=0; EX0=1; ledblink=0; } } void pulse (void) interrupt 2 using 2 { EX1=0; fan=1; switch(speed) { case 9: TL1=0Xb6; TH1=0XF8; break; case 8: TL1=0Xb6; TH1=0XF3; break; case 7: TL1=0X55; TH1=0XF1; break; case 6: TL1=0Xb6; TH1=0XF0; break; case 5: TL1=0X55; TH1=0Xf0; break; case 4: TL1=0Xdd; TH1=0XEf; break; case 3: TL1=0X22; TH1=0XEf; break; case 2: TL1=0Xa0; TH1=0XEe; break; case 1: TL1=0X7d; TH1=0XEe; break; } TR1=1; } void time2(void) interrupt 3 using 3 { TR1=0; fan=0; EX1=1 } void main(void ) { fanon=0 l1=l2=l3=l4=l5=l6=1; power=0; fan=1; led=0; speed=1; key1=0xff; key=0xff; TMOD=0X11; EA=1; EX0=1; PX0=1; while(1) { if(key1==0xc1) //1 { ledblink=1; l1=~l1; load1=l1; key1=0xff; } if(key1==0xc2) //2 { ledblink=1; l2=~l2; load2=l2; key1=0xff; } if(key1==0xc3) //3 { ledblink=1; l3=~l3; load3=l3; key1=0xff; } if(key1==0xc4) //4 { ledblink=1; l4=~l4; load4=l4; key1=0xff; } if(key1==0xc6) //6 { ledblink=1; load5=l5; key1=0xff; } if(key1==0xc5) //5 { ledblink=1; fanon=~fanon; l6=fanon; if(fanon) { EX1=1; ET1=1; else { fan=1; EX1=0; ET1=0; } key1=0xff; } if(key1==0xe0) //up { if(speed<9) { speed=speed+1; ledblink=1; } else speed=9; key1=0xff; } if(key1==0xe1) //down { if(speed>1) { ledblink=1; speed=speed-1; } else speed=1; key1=0xff } if(key1==0xcc) //power { ledblink=1; power=~power; if(power) { EX1=0; ET1=0; load1=load2=load3=load4=load5=fan=1; fanon=0; } else { load1=l1; load2=l2; load3=l3; load4=l4; load5=l5; fanon=l6; if(fanon) { EX1=1; ET1=1; } } key1=0xff; } } }

Low Cost 500W 12V To 220V Inverter Circuit

Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer.

How to calculate transformer rating

The basic formula is P=VI and between input output of the transformer we have Power input = Power output. For example if we want a 220W output at 220V then we need 1A at the output. Then at the input we must have at least 18.3V at 12V because: 12V*18.3 = 220v*1
So you have to wind the step up transformer 12v to 220v but input winding must be capable to bear 20A.

Attention: This Circuit is using high voltage that is lethal. Please take appropriate precautions

White LED Lamp Circuit

Nowadays you can buy white LEDs, which emit quite a bit of light. They are so bright that you shouldn’t look directly at them. They are still expensive, but that is bound to change. You can make a very good solid-state pocket torch using a few of these white LEDs. The simplest approach is naturally to use a separate series resistor for each LED, which has an operating voltage of around 3.5 V at 20 mA. Depending on the value of the supply voltage, quite a bit of power will be lost in the resistors. The converter shown here generates a voltage that is high enough to allow ten LEDs to be connected in series.
In addition, this converter supplies a constant current instead of a constant voltage.

Resistors: R1 = 1kΩ2 R2 = 68Ω Capacitors: C1 = 100µF 16V radial C2 = 680nF C3 = 100µF 63V radial Inductors: L1 = 200µH 1A Semiconductors: D1 = Schottky diode type PBYR745 or equivalent D2-D5 = zener diode 10V, 0.4W D6-D15 = white LED IC1 = LM2585T-ADJ (National Semiconductor)