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433 Mhz Single channel relay switch

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Member level 2
Apr 9, 2012
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Could anybody please supply me with a circuit diagram for a 433 Mhz single channel relay switch, I just want to switch on a mains pump by radio, I have searched the forum and google but cannot find what I am looking for.

Basically I have a 433 Mhz transmitter and receiver set, and HT12D & HT12E chipset, a small 5v coil songle relay etc

Thanks in advance

It seems you will:

1) press a button
2) the HT12E produces a coded signal
3) it goes into your 433 MHz transmitter somehow (as audio perhaps). Or you can inject the signal directly, if you feel certain you can open up the transmitter and find the proper point inside.
4) The radio broadcast goes over the air to your 433 MHz receiver.
5) A device is attached to the receiver, which will produce audio (or light beam?). (Or if you open up the 433 MHz receive then you can access it electronically).
6) The HT12D picks up the signal.
7) If it is the correct code, the HT12D turns on the relay. A different code turns it off.

The interface devices are what you must construct. The sending device may be easier to make. Maybe it can be a speaker (depending on whether the 433 MHz transmitter can accept audio).

The receiving device will be a sensor, perhaps a microphone(?). It must correctly convey the code coming from the 433 MHz receiver. Then feed it to the HT12D.

You need to discover the nature of the codes. The information (as a pulse train, frequency, whatever) must be preserved throughout the entire process.

As for the relay, it requires a certain amount of current in order to turn on. If you're lucky the HT12D should be able to provide sufficient current. If it isn't then an additional component or two will be needed.

There are two modes you could use for your switch :- RF power on = mains on (no rf = no mains) and rf power on, mains goes on, rf power goes off mains stays on, rf power comes on, mains goes off. rf power goes off, mains stays off. I would recommend the second mode if you can see or measure the result of the mains being on, because as the transmitter is only used for bursts its battery lasts longer. If however you are doing this with out any sense of whether the mains at the far end is on or not, the first method is the best you can do.
The DT12 chipset seems over kill (and complicated) for your application as its for transmitting up to 12 different bits of data. A bit of data on your TX and RX chips would be of interest.

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