- PRODUCT DESCRIPTION
- FUNCTIONAL BLOCK DIAGRAM
- CIRCUIT DESCRIPTION
- CIRCUIT DIAGRAM
- LIST OF COMPONENTS
- PCB LAYOUT
- PCB FABRICATION
- SOLDERING PRACTICE
- DATA SHEETS
Remote control for home appliances is an absolute necessity in our fast-paced life. As a result, much important has been given to this aspect and a range of remote controls are prevalent today. One of the most common is that which makes use of IR radiations at particular frequencies.
Our product is a Remote Operated Home Appliance or Remote controlled Home appliance. The circuit is connected to any of the home appliances (lamp, fan, radio, etc) to make the appliance turn on/off from a TV, VCD, VCR, Air Conditioner or DVD remote control. The circuit can be activated from up to 10 meters. It is very easy to build and can be assembled on a general-purpose PCB.
The circuit essentially consists of a transmitter consisting of a 555 IC, the receiver consisting of an IR module, CD4017 IC, LED’s to indicate the reception of the IR radiations, otherwise indicating the ON/OFF state, relay and other components.
Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance turn on/off from a TV, VCD or DVD remote control. The circuit can be activated from up to 10 meters. The 38 kHz infrared (IR) rays generated by the remote control are received by IR receiver module TSOP1738 of the circuit. Pin 1 of TSOP1738 is connected to ground, pin 2 is connected to the power supply through resistor R5 and the output is taken from pin 3. The output signal is amplified by transistor T1 (BC558). The amplified signal is fed to clock pin 14 of decade counter IC CD4017 (IC1). Pin 8 of IC1 is grounded, pin 16 is connected to Vcc and pin 3 is connected to LED1 (red), which glows to indicate that the appliance is ‘off.’
The product consists of a remote which is the transmitter of the IR radiations and the receiver which responds to the radiations and switches ON and OFF the appliance.
The transmitter is basically an astable multivibrator using 555 timer IC which provides a 38 kHz frequency at its output. The circuit here uses 555 timer IC to avoid fast switching. (This can also achieved by using a high value capacitor across TSOP sensor.) You can only switch the circuit after 3 seconds. The design for the circuit is as given below.
Frequency f = 1.45/ (R1+2R2)C
Required f = 38000Hz
R1 = 1.2k
R2 = 4.7k pot
C = 10 nF
555 TIMER IC: The 555 Timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation and oscillator applications. The 555 has three operating modes:
- Monostable mode: in this mode, the 555 functions as a “one-shot”. Applications include timers, missing pulse detection, bounce-free switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) etc
- Astable – free running mode: the 555 can operate as an oscillator. Uses include LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position modulation, etc.
- Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used. Uses include bounce-free latched switches, etc.
Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance turn on/off from a TV, VCD or DVD remote control. The circuit can be activated from up to 10 meters.
The 38 kHz infrared rays generated by the remote control are received by IR receiver module TSOP1738 of the circuit. Pin 1 of TSOP1738 is connected to ground, pin 2 is connected to the power supply through resistor R5 and the output is taken from pin 3. The output signal is amplified by T1 (BC558). The amplified signal is fed to clock pin 14 of decade counter IC CD4017 (IC1). Pin 8 of IC1 is grounded, pin 16 is connected to Vcc and pin 3 is connected to LED1 (Red), which glows to indicate that the appliance is ‘off.’
The output of IC1 is taken from its pin 2. LED2 connected to pin 2 is used to indicate the ‘on’ state of the appliance. Transistor T2 (BC548) connected to pin 2 of IC1 drives relay RL1. Diode IN4007 (D1) acts as a freewheeling diode. The appliance to be controlled is connected between the pole of the relay and neutral terminal of mains. It gets connected to live terminal of AC mains via normally opened (N/O) contact when the relay energizes. Result, we get a relay toggling on each press on the remote.( If a DC 12 volt relay is to be operated, then a regulated DC 12 volt power supply is used and the circuit voltage should not exceed DC 5 volts). Any appliance connected to this circuit can be switched ON or OFF.
PHOTOMODULE (TSOP1738): The TSOP17XX – series are miniaturized receivers for infrared remote control systems. PIN diode and preamplifier are assembled on lead frame, the epoxy-package is designed as IR filter. The demodulated output signal can directly be decoded by a microprocessor. TSOP17XX is the standard IR remote control receiver series, supporting all major transmission codes.
CD4017BC IC: It is a 5 stage divide by 10 Johnson counter with 10 decoded outputs and a carry out bit. The configuration of this IC permits medium speed operation and assures a hazard-free counting sequence. The 10/8 decoded outputs are normally in the logical “0” state and go to the logical “1” state only at their respective time slot. Each decoded output remains high for one full clock cycle. The carry-out signal completes a full cycle for every 10/8 clock input cycles and is used as a ripple carry signal to any succeeding stages.
RELAY ( 5V DC): Relays are components which allow a low-power circuit to switch a relatively high current on and off, or to control signals that must be electrically isolated from the controlling circuit itself.
The materials required for PCB fabrication are copper clad sheet, paint, drilling machine and ferric chloride solution.
Steps involved in making a PCB:
- Preparing the layout of the track: The track layout of the electronic circuit may be drawn on a white paper. The layout should be made in such a way that paths are in each routes. This enables PCB to be more compact and economical.
- Transferring the layout to the copper: The layout made on white paper should be redrawn on the copper clad using paint or nail varnish.
III. Etching: Ferric chloride solution is popularly used etching solution. The ferric chloride powder is made into a solution using water and kept in a plastic tray. Immerse the markedcopper clad in this for two hours. Due to reaction, the solution will become weak.The copper in the unmarked area will be etched out. Take out the etched sheet from the tray and dry.
- Drilling: The holes are made using a drilling machine, for component insertion.