RF remote Control - Need Help

[Lavan]

Hello Friends, I am trying to build 4 channel RF remote control device for controlling home appliances. I am using HT 12E & HT 12D. I have attached the circuits I am using, its working but not the way I want. Every time I press one push button or any of AD8 to AD11 makes low, the respective output on HT12D is going low. When I press another push button, its resetting the previous state and making only that respective output low. I want to operate these outputs independently. For example, I will be using one output for FAN and one for Light, etc., When I want to switch on the FAN, it should not change the state of light or any other output. Can someone please help me how to achieve this? Any ideas or help is greatly appreciated.

 

[ccurtis]

Try connecting the input of a toggle flip-flop (see attached) to each one of the two outputs of the HT12D receiver you are using. Each time a pushbutton is pressed and then released on the transmitter it will change the output state of the corresponding toggle flip-flop without affecting the state of the other flip-flop.

A CD4013 Dual D Flip-Flop IC has two independent flip-flops that can be connected to serve as two independent toggle flip-flops. One for Fan, the other for Light.

Of course, you will need suitable drivers for the fan and light since the CD4013 cannot drive them directly.

 

[Boncuk]

Hi Lavan,

firstly HT-chips are no RF-chips. They are IR-chips.

The worst of all is the fact that the HT12E is obsolete and you'll probably be able to get one remainder of the stock of an SEA-electronics supplier.

Here is a four channel IR-transmitter schematic using the latest transmitter chip (HT6220A) by Holtek.

It is well suited for the HT12D (receiver chip).

For transmitter and receiver use the same addresses. They are device addresses and must be set for the same device.

Eagle files for transmitter and receiver will be provided on request.

Boncuk

 

[ccurtis]

Scratch my previous reply. I looked at the datasheet for the receiver and the outputs of the receiver are latched, so repeated presses of the same pushbutton will not cause a change at the output of the receiver. You MUST send a different switch combination or the receiver output will not change at all. You can use a pair of pushbuttons, one for OFF, the other for ON, for each device you are controlling and use the corresponding outputs on the receiver to drive an R-S type Flip-Flop for each device.

There is a data valid output that changes state any time any button is pressed. That signal may be worked in for a different solution. I have to run now, though.

 

[Lavan]

@ Boncuk, thanks for your response. But I am confussed. You says, HT Chips are no RF support, but datasheet for HT12D & HT12E says these can be used for RF applications. Thanks for referring HT6220A. As per datasheet, its support only IR, no RF support. I am looking for RF remote. Is there any substitute for this which will work for RF?


@ ccurtis, thanks for your reply, If I take this approach, I have to use two more chips for flip flops for controlling 4 devices and 8 switches (2 switches for each device for ON and OFF) right?. I am looking for a simple approach with just 4 push to make switches for controlling 4 devices, 1 switch per 1 device for both on and off. I have seen an commercial remote with works on PT2272 (I believe this one and HT chips work in the similar way) without any flip flops. So looking for the way how to achieve the same with HT12E and HT12D. Not sure if that is possible.

 

[Reloadron]

Sans the mentioned chips I have had good success using the K180V3. ROLLING CODE 4-CHANNEL UHF REMOTE CONTROL with RESET ON EACH CHANNEL the data sheet for which can be found here.. Jumpers allow for latched operation or momentary. The transmitter is a 4 button key-fob. The system uses the 4 button Tx unit 4312RSA(01) and the receiver group is the 3302D4-15(2A1).

They are marketed as kits from several sources last time I looked so a Google of K180V3 should bring up several hits. They are easily hacked and modified. Additionally I have seen fewer channel and more channel kits depending on what you want to send. The units I have worked with gave good range of about 100 meters in open line of sight and also did well with walls in confined areas for less distance.

Something along these lines may or may not be worth looking into for your purposes.

Ron

 

[ccurtis]

@ ccurtis, thanks for your reply, If I take this approach, I have to use two more chips for flip flops for controlling 4 devices and 8 switches (2 switches for each device for ON and OFF) right?. I am looking for a simple approach with just 4 push to make switches for controlling 4 devices, 1 switch per 1 device for both on and off. I have seen an commercial remote with works on PT2272 (I believe this one and HT chips work in the similar way) without any flip flops. So looking for the way how to achieve the same with HT12E and HT12D. Not sure if that is possible.

Without added external gates/flip-flops to the HT12D receiver, what you want to do is not possible.