How to controle some Relays through RF.

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iftikhar_abid

Joined: 04 Jan 2009
Posts: 14
Location: Karachi, Pakistan

07 Jan 2009 12:59 How to controle some Relays through RF.

Hi,

Dear i want to make a telemetry project.
i want some ideas that how to make a relay ON OFF which is connected to a 89c51 controller with a receiver. i want to sent some sort of signal through my transmitter to the receiver and the controller switch on that particular relay.

Also mention the transmitter and receiver suitable for 500 meter range.

Thanks

Iftikhar Abid

hameeds01

Joined: 23 Aug 2005
Posts: 308
Helped: 15
Location: NUST Islamabad

07 Jan 2009 13:55 Re: How to controle some Relays through RF.

Dude its very simple , u need FSK modulator & demodulator,

at transmission side
i/p-----microcontroller-----FSK modulator ------ RF Tx
at receiving side
RF Rx-----FSK demodulator-------microcontroller-------Relays Drivers----- Relays

Thatz it
Transmit some code eg 11011011 & at Rx side decode it & trigger the desired relay

pranam77

Joined: 22 Apr 2008
Posts: 1071
Helped: 94
Location: Mangalore(India)

07 Jan 2009 14:03 How to controle some Relays through RF.

Refer similar 2 readymade projects from www.united77.com whose description is given below.

1.Multipurpose Four channel Radio Frequency Remote with 89C2051 microcontroller.
This is a remote controller which can be widely used in robotic application when in momentary mode. All the 4 channels can be individually programmed as latched outputs for lighting loads or momentary outputs for bell or any other automation requirement. Receiver side is equipped with four relays at the out put which can be wired in any configuration for the required operation. 4 individual addresses can be selected to operate more than one remote kit at a time.

2. Radio frequency based 4 channel Remote for robotics based on “Holtek” En/decoders. This is a remote controller which is widely used in robotic application where in momentary mode, 4 channels are available. Receiver side is equipped with four relays at the out put which can be wired in any configuration for the required operation. Individual addresses can be selected to operate more than one remote kit at a time.

Ready to assemble kits are available with PCB, Programmed Microcontrolers, schematics and component layouts on CD. Just requires to be assembled to make it work. Good luck

iftikhar_abid

Joined: 04 Jan 2009
Posts: 14
Location: Karachi, Pakistan

07 Jan 2009 14:26 Re: How to controle some Relays through RF.

Thnx fjor all that.
but dear if i use FSK at the receivng, will i need an encoder because the signal will be in analog form. if i need encoder then kindly suggest which one will be suitable.

hameeds01

Joined: 23 Aug 2005
Posts: 308
Helped: 15
Location: NUST Islamabad

07 Jan 2009 15:24 Re: How to controle some Relays through RF.

the o/p of the FSK demodulator is digital OK, u can connect it directly with microcontroller, i did it 2 years back
XR2206 ----->mod
XR2211------>demod

Regards hameeds
hameeds01(at)yahoo.com

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iftikhar_abid

Joined: 04 Jan 2009
Posts: 14
Location: Karachi, Pakistan

07 Jan 2009 15:53 How to controle some Relays through RF.

okay thnx.
but dear i am confused of one thing
supose i want to send some code ie 1010101 to switch on a perticular relay. but if i send it and the recver is off then definatly i will los the code. it means i will switch on the recver first before sending the code.

after sending 1010101 and then to send some other code like 11001100 to on another relay. kindly tell me should i send it just after the first one?

if u can suggest some protocol then do it too. thnx dear.