need help selecting a transmitter and reciever

ok, basically I want to turn on and off an analog switch wirelessly. The range I need is very short... maybe around 20ft. And I need a
transmitter as small as possible, and hopefully can run on a small battery (like a key fob and a watch battery). The transmitter only needs to be able to send 1 command to the reciever which would in turn tell my analog switch to open... I don't care how big the reciever is.... and this setup needs to be very responsive so that if someone taps the button on the transmitter side 10 times in 1 second, the reciever can open the switch 10 times in 1 second... very minimum delay, unpercitable... instant! I only want the switch to open while the button is pressed at all other times the switch should be closed....
anyway, that's basically it.... can anyone make any suggestions or point me in the right direction as far as where I could find a reciever and a transmitter that would fit my criteria? I imagine... its a pretty simple/basic application... but I know nothing about reciever/transmitters....
much thanks!
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On Tue, 21 Oct 2008 06:50:15 -0700, panfilero wrote:

I once got a little tranmitter/receiver pair at Radio Shlock - the Xmtr was like a key fob, and the receiver was a plug-in box about the size of a coffee timer; that could be adapted.
Good Luck! Rich
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On Tue, 21 Oct 2008 06:50:15 -0700 (PDT), panfilero

http://www.futurlec.com/Radio.shtml
These are very easy to use. Use a 4066, and drive it with the receiver.
Regards, Bob Monsen
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Thanks, do you know if I buy this... do I need to buy something called a encoder and decoder?
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On Wed, 22 Oct 2008 13:14:18 -0700 (PDT), panfilero

The encoder chip will ensure that you are only getting signals from the sender, and not from some other stray 415MHz signal. If you don't really care about that, you can just use the output as is. I used one of these to run a servo once. No encoder, just the tx and rx pair, and it worked quite well.
Regarding the 4066, you can't use it to switch signals outside the Vcc to Vss range. So, use a blocking capacitor, and then bias it into the middle of the range with two 100k resistors, one to Vss, one to Vcc. Then switch it. After this, use another cap to bring it back down to earth...
Note that you can only switch signals with this arrangement. If you are trying to switch a speaker, it won't work well, since the 4066 has pretty high resistance when it is on. There are newer switches that have much lower resistance.
Regards, Bob Monsen
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On Tue, 21 Oct 2008 10:13:59 -0700, Jim Thompson

Glad to help. BTW, I like futurlec, but they are sloooow... you might be able to get these things at digikey or arrow, and have them ship in this century :)
Regards, Bob Monsen
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panfilero wrote:

As has already been pointed out, you can't get "every" time. Your "minimum delay ... instant" requirement makes it tougher (although if you're talking about people in the loop 50ms is going to be imperceptible to all but the most perceptive users, and 20ms is probably safe for all but the Flash -- and he can just lump it).
Just any old consumer-grade tx/rx pair is likely _not_ going to cut the mustard, but I suspect that with a good receiver (you _can_ plug the receiver into the wall, right?) you can make this work, even with a key fob transmitter.
So, as Jan already said, tell us what you're _really_ doing.
--

Tim Wescott
Wescott Design Services
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If you are wanting something like a remote-control ventriloquist dummy, then you don't really need that kind of speed. But, regardless, you might get by with taking apart a remote-control toy car. Not the better kind with proportional control, but the really cheap kind that only has a few buttons. Then, you can cut the wires to the motors and use them for your control. But, you will need some electronics knowledge so that you stay within the current and voltages you have available need.
Alternatively, is a source for a keyfob-style remote control kit. The link for the keyfob itself has listings for PDF's of the manuals, but the links aren't working. I have not used this, and have no idea if you can get the momentary output or speed that you need. http://www.kitsusa.net/phpstore/html/Remote-Control-Unit-Kits-35-1.html
I've seen similar kits elsewhere.
Joe Dunfee
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Thanks for the Suggestion
I don't know much (hardly anything) about this stuff.... some transmitter/reciever modules seem to come with encoder/decoder chips also.... are those required? I'm having a hard time finding just straight information on this stuff online.... just like.... reciever/ tranciever basics... like... what's an encoder/decoder....
I'm not going to control a ventriliquist thing... but what I want to be able to do is control an audio signal.... so when I push the button, then 10 feet away an audio signal will pass through my switch, but I have to be able to push the button and hear the audio at the same time.... which means I can afford some delay as long as its not perceptible to humans.... but I gotta be able to hit the button at least 10 times a second and get good tracking on that.... 10 times a second seems slow when talking about electronics, no?
this kinda brings up another question that I was wondering about... if I'm using a switch like the 4066, and the audio signal swings into the negative... is that ok? The chip says it handles analog signals no problem... but I don't know if my signal (which is in millivolts) would pass through ok if it has a negative swing... which it does
much thanks!
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Have you tried this bit? How good were you?
Deep
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No but with two fingers I bet I could hit 20Hz
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Bet you couldn't! >:) Think through what you need carefully. If it was really something widely needed, you'll find plenty of sources. And if it's NOT, then it's that much more important to be as accurate as possible because you won't get the right design otherwise. If you end up specifying 100 times the precision than a carefull examination proves you need, the cost might rise beyond simple shock value.
As people ALWAYS ask, sooner rather than later, what EXACTLY are you trying to do? The less evasive you are, the more people can help you (and the less likely thet are to think you want to reliably trigger a bomb...)
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In the past I've seen blister pack wireless door bells at walmart for ~$10.
On Tue, 21 Oct 2008 06:50:15 -0700 (PDT), panfilero

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