IR Remote Control Extender


IR Remote Control Extender

 

IR Remote Control Extender

 


If
you want control the DVD or TV/AV system that located in your living
room via the remote control when you sleeping in your Bedroom. this IR
extender will achieve this for you. Basically, it works as a repeater
that moves the IR signal to a different location. This is an improved IR
remote control extender circuit. It has high noise immunity, is
resistant to ambient and reflected light and has an increased range from
remote control to the extender circuit of about 7 meters. It should
work with any domestic apparatus that use 36-38kHz for the IR carrier
frequency.

IR Remote Control Extender

The main
difference between this version and the previous circuit, is that this
design uses a commercially available Infra Red module. This module, part
number IR1 is available from Harrison Electronics in the UK. The IR
module contains a built in photo diode, amplifier circuit and buffer and
decoder. It is centerd on the common 38kHz carrier frequency that most
IR controls use. The module removes most of the carrier allowing decoded
pulses to pass to the appliance. Domestic TV’s and VCR’s use extra
filtering is used to completely remove the carrier. The IR1 is packaged
in a small aluminium case, the connections viewed from underneath are
shown below:

How It works:
The IR1 module (IC3) operates on 5
Volt dc. This is provided by the 7805 voltage regulator, IC1. Under
quiescent (no IR signal) conditions the voltage on the output pin is
high, around 5 volts dc. This needs to be inverted and buffered to drive
the IR photo emitter LED, LED2. The buffering is provided by one gate
(pins 2 & 3) of a hex invertor the CMOS 4049, IC2. The IR1 module
can directly drive TTL logic,but a pull-up resistor, R4 is required to
interface to CMOS IC’s. This resistor ensures that the signal from a
remote control will alternate between 0 and 5 volts. As TTL logic levels
are slightly different from CMOS, the 3.3k resistor R4 is wired to the
+5 volt supply line ensuring that the logic high signal will be 5 volts
and not the TTL levels 3.3 volts. The resistor does not affect
performance of the IR module, but DOES ensure that the module will
correctly drive the CMOS buffer without instability.
The output from
the 4049 pin 2 directly drives transistor Q1, the 10k resistor R1
limiting base current. LED1 is a RED LED, it will flicker to indicate
when a signal from a remote control is received. Note that in this
circuit, the carrier is still present, but at a reduced level, as well
as the decoded IR signal. The CMOS 4049 and BC109C transistor will
amplify both carrier and signal driving LED2 at a peak current of about
120 mA when a signal is received. If you try to measure this with a
digital meter, it will read much less, probably around 30mA as the meter
will measure the average DC value, not the peak current. Any equipment
designed to work between 36 and 40kHz should work, any controls with
carrier frequencies outside this limit will have reduced range, but
should work. The exception here is that some satellite receivers have IR
controls that use a higher modulated carrier of around 115KHz. At
present, these DO NOT work with my circuit, however I am working on a
Mark 3 version to re-introduce the carrier.

Parts List:
C1 100u 10V
C2 100n polyester
R1 10k
R2 1k
R3 33R 1W
R4 3k3
Q1 BC109C
IC1 LM7805
IC2 CMOS 4049B
IC3 IR1 module
LED1 Red LED (or any visible colour)
LED2 TIL38 or part YH70M

Testing:
This
circuit should not present too many problems. If it does not work, arm
yourself with a multimeter and perform these checks. Check the power
supply for 12 Volt dc. Check the regulator output for 5 volt dc. Check
the input of the IR module and also Pin 1 of the 4049 IC for 5 volts dc.
With no remote control the output at pin 2 should be zero volts. Using a
remote control pin 2 will read 5 volts and the Red LED will flicker.
Measuring current in series with the 12 volt supply should read about
11mA quiescent, and about 40/50mA with an IR signal. If you still have
problems measure the voltage between base and emitter of Q1. With no
signal this should be zero volts, and rise to 0.6-0.7 volts dc with anIR
signal. Any other problems, please email me, but please do the above
tests first.

PCB Template:
Once again a PCB template has been kindly drafted for this project by Domenico.

Alternatives to IC3:
The
part number IR1 from Harrison Electronics is no longer available. They
do supply an alternative IR decoder which I have tested and works. Other
alternative Infrared decoders are shown below, note however that all DO
NOT share the same pinout. I advise anyone making this to check the
corresponding data sheets.

Vishay TSOP 1738
Vishay TSOP 1838
Radio Shack 276-0137
Sony SBX 1620-12
Sharp GP1U271R

Equipment Controlled Successfully:
If
you have built this circuit and it works successfully please let me
know and I will build the list. Email details of the Manufacturer,
device and remote control model number. The remote model number is
usually on the front or back of the remote.

IR Remote Control Extender

IR Remote Control Extender



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