The RF relay control, as the name suggests, operates at Radio Consistency. The corresponding consistency range may differ between 30 kHz & 300 GHz. In this RF system, the digital info is symbolized as different versions in the exuberance of carrier wave. These kinds of modulation is referred to as Amplitude Move Keying (ASK). Transmission through RF is preferable to IR (infrared) because of many and varied reasons. Firstly, alerts through RF can traverse larger miles making it suitable for long range applications. Also, whilst IR mostly operates in line-of-sight mode, RF signals can travel even if there is a great obstruction among transmitter & receiver. Following, RF tranny is more good and trustworthy than IR transmission. RF communication runs on the specific regularity unlike IRGI signals that happen to be affected by additional IR emitting sources. This RF component comprises of an RF Transmission device and a great RF Receiver. The transmitter/receiver (Tx/Rx) match operates at a regularity of 434 MHz. A great RF transmitter receives dramon data and transmits this wirelessly through RF through its antenna connected for pin4. The transmission takes place at the charge of 1Kbps - 10Kbps. The transmitted data is definitely received by an RF receiver functioning at the same consistency as those of the transmission device. The RF module is often used and also a pair of encoder/decoder. The encoder is used to get encoding seite an seite data to get transmission supply while reception is decoded by a decodierer. HT12E-HT12D, HT640-HT648, etc . a few commonly used encoder/decoder pair ICs.






•Encoder IC-HT12E

•Decoder IC-HT12D

•RF info transmitter module

•RF data receiver component

•Buffer IC-74541

•Relay rider IC-ULN2803


HT12E is a great encoder built-in circuit of 212 number of encoders. They are really paired with 212 series of decoders for use in remote control system applications. It is mainly utilized in interfacing RF and infrared brake lines. The chosen pair of encoder/decoder should have same number of addresses and info format. Flag Diagram:

To put it simply, HT12E converts the parallel inputs in to serial end result. It encodes the 12 bit parallel data in serial intended for transmission with an RF transmitter. These 12 bits will be divided into almost eight address portions and 5 data pieces.

HT12E provides a transmission permit pin which is active low. When a induce signal is definitely received upon TE flag, the developed addresses/data are transmitted along with the header portions via an RF or an infrared transmission channel. HT12E starts a 4-word transmission routine upon invoice of a indication enable. This kind of cycle is definitely repeated given that TE is definitely kept low. As soon as TE returns to high, the encoder outcome completes their final cycle and then ceases. Pin Description:

Pin number No Function Name

18 bit Address pins pertaining to inputA0








9Ground (0V)Ground

104 little Data/Address limits for inputAD0




14Transmission enable; active lowTE

15Oscillator inputOsc2

16Oscillator outputOsc1

17Serial data outputOutput

18Supply voltage; 5V (2. 4V-12V)Vcc


HT12D is a decodierer integrated circuit that is 212 group of decoders. This course of decoders are mainly utilized for remote control program applications, just like burglar alarm, car door control mechanism, security system etc . It is primarily provided to interface RF and infrared circuits. They can be paired with 212 series of encoders. The picked pair of encoder/decoder should have same number of tackles and data format. Pin Diagram:

In simple terms, HT12D converts the serial insight into parallel outputs. That decodes the serial addresses and info received by, say, an RF receiver, into parallel...

References:: http://www.circuitstoday.com/remote-control-circuit-through-rf-without-microcontroller#ixzz1YVVT7Q34

: http://jaspreetscodezone.blogspot.com/2008/01/interfacing-relays-using-parallel-port.html#ixzz1YQCdbpTh