wireless on/off switch

[Matt Warnock]

I'm looking for some information on making a wireless on/off switch. The
on/off portion i mean is just a pulse to hit a flip flop on a circuit in
another room of a house. I figured this is done on a simple IC or in a
simple circuit because i have a few devices that are simple remotes and
receivers that run relays or other devices. I'm not trying to transmit
information, just a pulse.

Does anyone have suggestions on where i can find information on this?
thanks

 

[GPG]

I'm looking for some information on making a wireless on/off switch. The
on/off portion i mean is just a pulse to hit a flip flop on a circuit in
another room of a house. I figured this is done on a simple IC or in a
simple circuit because i have a few devices that are simple remotes and
receivers that run relays or other devices. I'm not trying to transmit
information, just a pulse.

Does anyone have suggestions on where i can find information on this?
thanks

Wireless doorbell

 

[Frank Raffaeli]

Wireless doorbell

A wireless doorbell is more robust than sensing a "pulse". You could
build a reciever that was sensitive to *any* "pulse" of radio energy
at a tuned frequency. The problem is, it would be triggering all the
time due to noise and interference generated by ... well ...
everything.

The coding of "information" as you say it is the best way to insure
immunity to the interference. IC manufactureres like Holtek make
encoder / decoder chips for such a purpose. Encoding/decoding can also
be done with a microcontroller. As I have proven to myself recently,
some coding algorithms are better than others.

To learn how to make a simple radio transmitter-receiver pair, include
in your search the term "ASK" (amplitude-shift-keying) or "OOK"
(on-off-keying). A lot of the simplest "radios" work this way. There
are dozens of IC manufacturers for ASK, or you can use discretes. In
the receiver, the most common design is a "super-regen". It is used
because it is so cheap - usually one transistor and a base-band
(audio) amplifier. It's easy to get -90 dBm sensitivity this way, but
they are often prone to de-tuning if LC elements are used.

Frank Raffaeli
http://www.aomwireless.com/

 

[Matt Warnock]

Great, thanks for the information. I can't think it would be very
difficult. i took a small commercial unit i have apart. all i saw in the
transmitter was a very simple circuit, 2 transistors and a 27 mhz oscillator
and some caps & resisters. The receiver was an LC circuit and a few
transistors. I didn't see any ICs. Do you know where i could pre-design
schematics that i could use to understand this more?