IR Remote Controller Extender

If we are using a video extension from a TV, DVR, DVD player etc, we will come across a problem of controlling the main unit from a remote place from which the ordinary IR signals can not reach the receiver. For an example, if you have installed a satellite TV receiver in the living room or in the down stairs and a display in a bed room or in the up stairs, every time when you want to make any change you have to peep in to the place where the main unit is. But in this case if you can control the main unit from where the display is, how comfortable you will be?  OK, I have designed a circuit for that and tested. It worked very well. It is a very simple circuit designed using commonly available inexpensive components excepts IR sensor module. 

        

        This is the Circuit diagram.

Circuit Description

The main function of this circuit is to receive the IR signal from a remote place by the IR sensor module and emit that near the main unit using IR LED s. So as shown in the 

circuit diagram, you have to keep the main circuit in the place where the IR remote controller is (eg: in the room) and IR LEDs near the main unit (eg: in the living room). So LED s should be connected using a long wire.

As the IR sensor module, you can use a commonly available device. But it should be sensitive to the main unit's remote controller. As you know IR signal is not a pure digital signal. It is a modulated signal with a frequency around 400 kHz. It is done so mainly to eliminate interference from the environment. IR sensor module demodulates the IR signal and output digital signal. So we can not use that signal to light IR LED s near the main unit. Before emitting through IR LED s the demodulated signal should again be modulated with a wave having frequency around 40 kHz. IC1-c and IC1-d has been set as an astable multi-vibrator to generate the required frequency. Use VR1 preset to tune the circuit.(when you generate the correct frequency the circuit will work fine). The circuitry built with T1 and T2 transistors modulate this wave and the digital signal. Ultimately it is emitted near the main unit by IR LED s. For these, a current limiting resister is not generally needed, as they are turned on only for few milliseconds. If you experience burning of your IR LED s, just use a resistor of few hundreds ohm in series with them.    

IR Remote Control Switch Using CD4015 IC

This circuit was designed around IR sensor module, NE555 timer and CD4015 4-bit shift register. You can use any IR sensor module commonly used in TVs and radios. So the same remote controller can be used to control this.

         Here is the circuit diagram.

In response to the IR signal received by the IR sensor module, it outputs a digital signal. It is a train of pulses. As it is not a constant impulse, it can not be used directly to control a target circuit such as a relay. NE555 timer has been set as a mono-stable multi vibrator to get a constant impulse of ~500ms duration in response to the digital signal received from the IR sensor module. Due to this reason, once triggered, NE555 can not be re-triggered for ~500ms duration.

CD4015 4-bit shift register is working as a bi-stable multi vibrator(Flip-Flop). Impulse

received by the pin no:1 can change the state of the flip-flop. A special circuitry included here resets the circuit at the time of  power on. So at the time of power on, the relay is always kept off, certifying the reliability. When the relay is in the power off state, an LED will light to indicate the standby mode.

This was designed and tested by me and found to have no errors.

IR Remote Control Switch Using CD4017 IC

          This is a simple IR(Infra Red) remote control switch based on IR sensor module, NE555 timer IC and CD4017 decade counter.The circuit was successfully tested and found free of errors.

         This is the schematic.

 Circuit Description

           The circuit was designed to be powered by a 5 v supply. Thus a 5 v relay is used to control the target circuit. You can use any kind of common IR sensor module which is used for TV or radio. So you can use that remote controller to control the relay.

          In response to the IR signals emitted  by the remote controller, the IR sensor module produces a train of electric signals. That is a digital signal. It is then fed to the pin no:2 of NE555. Operating as a mono stable multi vibrator, the NE555 circuit prevents all the digital signal from the IR sensor module passing to the pin no:14 of CD4017. Instead, NE555 is triggered with the very first falling edge of this digital signal. With thtis triggering, pin no:3 of NE555 goes high wich is last for a time duration determined by the R3 and C2 circuitry. It is around 500ms. For that time NE555 becomes insensitive to trigger signals.So NE 555 outputs a positive impulse keeping at least a gap of 500ms. Therefore whatever the frequency of triggering signal, once triggered, NE555 is unable to output a signal until 500ms is passed.

         Here CD4017 acts as a Flip-Flop. To improve the reliability of the circuit, an auto power on reset circuit has been built around T1 transistor. That is every time when  the circuit is powerd on, the circuit goes to the reset state. In the reset state the pin no:3 of CD4017 goes high lighting the LED1; the standby indicator. When the CD4017 is clocked once, pin no:3 goes low and pin no:2 goes high energizing the relay.If  another signal after 500ms clocks CD4017, again it goes to reset state. This operation goes on and on as long as IR signal is received.

Special Features

1. No multiple clocking of CD4017 per button click due to the circuitry based on NE555.
2. Reliable power on reset state maintained by the Auto Power On Circuitry.