An RF Transmitter and receiver that allows multiple contacts at the same time

[HalloweenBob]

I'll start with what I want, just in case there's a way to do that, then I will propose my solution and see if it is something that already exists, or something that can be built.

First, what I am looking for.

I wanted a simple 12 channel wireless remote that would close relays at the receiver end when buttons were pushed on the transmitter end.

I found hundreds of places to buy these very inexpensively and they were all very similar. I don't need much range (Maybe 30 to 50 feet). the ones I found could be purchased for anywhere between 20 and 50 dollars.

The one universal flaw in all these units is that they are incapable of closing more than one relay at the same time. Once you are holding down one button in momentary mode, no other button will function when pressed. I have wired in 2 joysticks to where the push-buttons were and for my purposes, it is necessary to have both momentary switch mode and to be able to activate multiple channels at the same time.

I did find a solution to this problem, but it would cost upwards of $700.00, and that is well beyond my budget.

So, my first question is, does anyone know of such a transmitter/receiver set that is capable of doing what I need at the lower end of the cost scale, or does anyone know of a way to modify an existing one to make it function that way.

If not, is there a circuit I could build that would detect how many switches I am holding down which would rapidly alternate or step through all the switches multiple times a second, sending that output to the actual remote that I have?

The idea is this:

1. I hold down 3 switches at the same time.
2. The circuit I build would be in-between my switches and the switches on the remote control. It would detect the switches I am holding down (Let's say they are switches 1, 2 and 3) . the circuit would in turn close switch 1 on the remote transmitter for 2 milliseconds (or some other pre-set duration), then open it and close switch 2 on the transmitter for 2 ms, then open it and close sw 3 for 2 ms, then repeat for as long as that combination of switches are being held down. If only one switch is being held down, it would not pulse, but just let that one switch be connected. The pulsing would only happen when two or more switches were held down at the same time.

That way, as far as the transmitter is concerned, only one button at a time is being held down. It is just switching between them so rapidly that it appears from the motion that multiple things are happening at the same time to the eye. I would have to be able to adjust the duration to allow for enough time for the signal to be sent and for the receiver to react before the next signal is sent, but my guess is that I could find a duration that would work and not create a noticeable 'stepping' effect in the motion of the cylinders I an driving.

So my question is, does this sound like a reasonable solution, and does anyone know where I can find plans or schematics for such a circuit?

Thanks,
Bob

 

[Nigel Goodwin]

This sort of project is what PIC's were made for, and is what you need - you can then program them to do whatever you want.

 

[dr pepper]

If I get your explanation right your going about it the wrong way round, a microcontroller on the receiver end can operate as many outputs as you like from just one received signal from a rf receiver module, so 1 button on the transmitter can operate more than 1 o/p relay or whatever.
I have led sucurity lights controlled by a keyfob, using a similar system, different buttons on the 'fob control different lights and timeout durations, I used a pic an entry level one.
Your method of scanning switches on the remote has issues, a lot of these tend to multiplex the input buttons, and also the transmit rate can be slow esp if the transmitter encodes its o/p, it might work but you'd probably only get 1 or 2 transmissions per second depending on the system.