How to make a wireless adaptive switch for disabled people?

I want to make a wireless adaptive switch with a feature of momentary and latch-timer mode for disabled people. The switch can be used for any toys or equipments with 3.5mm jack. There are some questions that I concern.
1. What kind of RF module (transmitter and receiver) should I use to make it wireless?
2. How do you implement the switch so that it can work on momentary and latch-timer mode. Do i need to use any PIC chip ?

Looking for your input! Thanks in advance

Linx.com makes a number of modules, including key FOB transmitters (like on cars) and receiver modules. If you don't want to buy a ready built module but want to make it yourself I buy the transmitter modules and reciever modules and hook them to a microcontroller. They also have encoder chips and decoder chips you can use instead of a micro. Then you could assign one channel as a momentary control, and assign a 2nd channel to start a timer. The design of this timer would depend on how long you want it to time for.

If you want to design your own transmitter/reciever, then google it and there are lots of schematics out there. The most popular method is DTMF.

Thanks for the reply , Mike! If I want to to buy the built in transmitter modules and receiver modules, then I would need to hook the to microcontroller. If Iam using the micro chip, can I assign the channels for for different mode (momentary and timer) ? Or I must have the encoder and decoder chip?

These modules run at 3.3V, so run your micro at the same voltage. If you're using a micro on both ends, you only need to encode your message to tell the receiving micro whether you want a momentary pulse or timed pulse. If you use the encoders you will need two channels, and not necessarily have a micro on the receiving end. Although, for long time delays, you can't beat a microcontroller.

actually, in the previous email, I gave you the wrong email, it's linxtechnologies.com

Do you know what kind of transceiver, receiver and micro chip I should use ? And how do I connect them to the switch. It will be great if you can give a sample diagram or schematic showing how to connect them together. Thanks

well, the selection of a microcontroller is a very personal thing. It even varies project by project... the right tool to do the right job.

However, in your case, it would be more of an availability issue. Which ones can you buy? Which ones can you program? If you can't now, how much can you afford to buy one???

I use the AVR, ATMEGA series. You can be up and programming them for less than $50. All you would have to buy is a programmer ($29+tax/shipping at digikey.com) and then download the development software for free Atmel. I use Studio4. I know it is older, but I do all my programming in assembly and I'm used to it (you don't want to know how many years it took me to upgrade from studio3)...

Probably too big for what you want to do. You can probably use an 8 pin micro that has upto 6 I/O would be all you need.

You won't need a micro for the transmit side, just the encoder hooked up to the transmitter module. For the receiver side, the two outputs (or more if you have the I/O, why limit) that come out of the decoder feed two port pins on the micro. The micro can then drive a transistor to turn on a relay to give you an output. The micro can do all the timing. You never did say how long of a delay you needed... I see three modes, momentary (on while receiving signal), timed (signal starts a timer), and latched (on with signal, then off with the next signal, etc.), or you can use one channel to turn on a latched relay, and a second channel to turn off the relay, eliminating the need for a micro.

on the data sheet I posted, it shows the connection. The encoder just needs power and the pushbuttons. It then goes to the tranmsit module. This module just has a signal input, an enable pin which you would tie to always enable, power, and an output to an antenna.

On the schematic posted this post, the 750 ohm R10 can be lowered to 300 ohm by using 3.3V. It limits the power output so you don't get into trouble from the FCC. The data out of the encoder would be connected to the data pin (2) of the transmit module. Don't let PDL going to RxD fool you. it is NOT bidirectional. I use that pin as an output to enable/disable the transmitter.

The receive module is the same, only in reverse.
Don't worry about the RSSI signal, that's just receive signal strength. I use it to help filter my results.

thangngoc said:

Do you know what kind of transceiver, receiver and micro chip I should use ? And how do I connect them to the switch. It will be great if you can give a sample diagram or schematic showing how to connect them together. Thanks

Click to expand...

connections of the encode/decoder chips is shown in 3rd diagram of post #4.

I think I am going to buy the TWS-434A RF Transmitter Module and RWS-434 RF Receiver Module at Reynolds Electronics Remote Control Store .Do you think they are going to work with the any mic chip?
You said that I only need one mic chip and a decoder at the side of receiver module ? and for the side of transmitter is just the encoder ?
p.s The timer mode, I would like to have a Timed Seconds (1-60s) and a Timed Minutes (1 to 60 minutes)

thangngoc said:

I think I am going to buy the TWS-434A RF Transmitter Module and RWS-434 RF Receiver Module at Reynolds Electronics Remote Control Store .Do you think they are going to work with the any mic chip?
You said that I only need one mic chip and a decoder at the side of receiver module ? and for the side of transmitter is just the encoder ?
p.s The timer mode, I would like to have a Timed Seconds (1-60s) and a Timed Minutes (1 to 60 minutes)

Click to expand...

yes looks good... this pair should work. The schematic is right there on the website, did you see it? They even showed the encoder/decoder pair and how to hook them up.

well, I wouldn't go out on a limb and say ANY micro, but the vast majority, yes, they should work fine. Let's see, 60 second time delay in hardware is not undoable, but 60 minutes would be difficult. A micro would help enormously.

https://jap.hu/electronic/codec.htmlThis guy has something like you are looking for.