Saturday 4 May 2013

Remote Control Circuit Through Radio Frequency Without Micro controller.

Remote Control Circuit
Through Radio Frequency
Without Micro controller.

Til now we were listening about
controlling electrical home appliances
with TV remote but there was a
problem that by the help of TV remote
we could control only one electrical
appliance at a time. Now in this post I
have brought a new circuit for you
that is Remote Control Circuit
Through Radio Frequency Without
Micro controller. Surprised??? Yes this
circuit doesn’t need any kind of micro
controller.This simple remote control
circuit uses radio frequencies to
control the electrical appliances and
the most important thing is that it
can control electrical appliances
within the range of 400 foots. The
circuit is no more complex.
It has only
two simple sections as
you know in
the remote control circuit.
First one is
transmitter and second one is receiver
circuit.
The transmitter circuit is our
remote control circuit and the receiver
circuit is for our electrical appliances.
When we press any key in the
remote control it generates some
corresponding RF signals to the
receiver circuit that acts according to
these RF signals.

ASK transmitter and
receiver circuits are used for the
transmitter and receiver in this remote
control circuit. Two HT12E and HT12D
encoders and decoders are used in
this simple remote control circuit. The
block diagram of circuit is given
below.
Remote Control Circuit Through RF
Block Diagram
Remote or Transmitter
Section:
The transmitter or remote control
circuit has two circuits. One is HT12E
encoder and the second is ASK
transmitter. The function of encoder
(HT12E) is to generate 8 bit address
and 4bit data. There is a DIP switch
given in the transmitter circuit in A0 to
A7 in the encoder to set the address.
If we set an address in the transmitter
section the same address is used in
the receiver section to switch on or off
the electrical appliance. When we
press any key in the remote section
then it generates 4 bit data that are
sent by using 8bit address lines by
using the ASK transmitter. The
Remote Control has frequency of 433
MHz and the output of transmitter is
up to 8 mW at 433.62 MHz frequency
with a range of 400 (for outdoors) and
200 foot for (indoors).
The circuit diagram of
Remote Control Circuit
(Transmitter) is given
below:
Remote Control Circuit Through RF
Transmitter Circuit Diagram
Receiver Section:
Now come to the Receiver Section of
the circuit. As I have said already that
both transmitter and receiver are ASK
so there will be an ASK receiver in the
receiver circuit. The receiver also
operates at the frequency of 433.92
MHz and has a sensitivity of 3 uV. 4.5
to 5.5 DC voltage is required to
operate the receiver and to get the
linear and digital output. First it
receives the encoded data that are
sent by transmitter then decodes
them using HT12D decoder and it will
enable the corresponding output pin
(10,11,12,13). Each output pin is
connected to its flip flop that is in
reset state. The output of decoder
changes the stat of corresponding flip
flop of the output pin and output
goes to set(high) from reset (low). A high signal is generated by the flipflop due to stat change in flipflop.
This output of flip flop is not enough
to drive a relay used for the particular
electrical appliance, so we have to use
a current driver. A SL100 transistor is
used as a current driver. The electrical
appliance is connected to 230 voltage
directly through the relay. The relay is
switched on by current driver and
electrical appliance switches on.

The relay switches off again
if we press
the same switch again in the remote
control because in this situation the
decoder goes to just opposite (low to
high) and the stat of flip flop is
changed again and relay stops its
working and the electrical device
switches off.

The circuit of Receiver is
given below:
Remote Control Circuit Through RF
Receiver Circuit Diagram
Following components are used in
this Remote Control Circuit

IC HT 12D 1
CD 4017 4
LM 7805 2
TRANSISTOR BC 558 4
SL 100 4
RESISTOR 180 K 4
1 K 4
560 E 4
39K 1
1M 1
CAPACITOR 100nF 4
100MFD/16V 4
LED RED 4
DIP SWITCH 2
PUSH TO ON SWITCH 4
ASK TRANSMITER 433MHZ 1
ASK RECEIVER 433MHZ 1

There is no use of micro-controller so
the circuit doesn’t cost so much and
can by easily assembled.
There are many other remote control
circuit are available on the internet
but I liked it very much. I hope you
enjoyed this wonderful Remote
Control Circuit.

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