one channel radio frequency help

I could use some input on this subject. A while ago I used infared led's hooked up to a 555 to flash at a certain speed, I can't remember what speed it was but I then had some special little divice that when it saw an infared flashing at one specific givin speed it would either close a switch completing the circuit, I can't quite remember how I wired it but any way I'd like to do the same with a radio. What I want it to do is turn on and led first than move on to turning on ovens, unlocking cars etc... I have a good idea how to do it, just take a transmiter and pulse it at a certain speed with a 555 but how do I get my reciever to only regonize that certain speed, a filter, a tone detector? I could really use some input or websites to look at.

Reply to
robot guy
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Make it up from scratch again, just like you did the first time, as you seem to indicate[1]; and this time, if you're too drunk or zoned to remember, take notes. For that matter, take notes anyway.

And always remember the first tenet of "State-Dependent Learning": "If you can't learn it while you're high, you can't learn it."

And, just because I'm feeling frisky at this moment in spacetime, I feel like ripping off one of Uncle Jimbo's lines: "Kids, there's a time and a place for everything, and that's College!"

Have Fun! Rich [1]: "A while ago I used infared led's hooked up to a 555 to flash at a certain speed ..." [1A]: "I can't quite remember how I wired it..."

Reply to
Rich Grise, Plainclothes Hippi

Only problem is that the I don't know what was causing the device to only respond to a certaing rate of speed from the flashing led. It was all pre manufactured into a little sugur cube sized box.

Reply to
robot guy

I did something like this once to unlock my car and house by just walking up to them. It used a PIC for the sending unit banging out a very short code pulse about once a second and then going back to sleep.

It worked great 'on the bench' and totally failed in any bright daylight.

Luhan

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Reply to
Luhan

Look at garage door openers, they use coder (usually set with bank of swithes) in transmitter AND receiver. When those two codes match an action is performed. But you have to have different music for every item that you want to respond to your orders.

Something to do.

HTH

Stanislaw

Reply to
Stanislaw Flatto

"robot guy" wrote in news:1175634612.259231.224850 @p77g2000hsh.googlegroups.com:

You had, likely, a typical IR reciever module from a VCR os the like. The simply detect the presence of an IR signal oscillating at around 40 Khz, and activate (pull to ground) the output pin at the presence of the 40Khz IR signal. Your 555 was blinking the IR LED at the set frequency for that module. A typical IR remote would modulate that carrier by turning it on and off in the data pattern the remote creates.

RF remotes are similar, in that instead of a 40 Kz carrier on an IR LED, the data pattern is directly modulates the transmitter. In theory, you could do the the same, by gating an RF carrier, and detecting its presence, but that is less than ideal. You should encode it, and depending on the application, you should have a self error checking code.

Reply to
Gary Tait

If you can bother you can find chips that do both the transmit and receive functions for IR or RF remotes. They are typically marketed in transmit - receive pairs. There are usually inexpensive ceramic resonators to generate master clock frequencies for both parts.

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 JosephKK
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Reply to
joseph2k

joseph2k wrote in news:Q9mUh.8929$ snipped-for-privacy@newssvr21.news.prodigy.net:

Nowadays though, the system controller of the device being controlled decodes the data coming from the IR or RF receiver, rather than a standalone decoder IC.

Reply to
Gary Tait

I was talking about the transmitter and receiver IC's themselves. Even in my very old designs the decision on what actions to take were made by a micro that defined the application.

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 JosephKK
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Reply to
joseph2k

joseph2k wrote in news:gznWh.5181$ snipped-for-privacy@newssvr14.news.prodigy.net:

Well, for typical IR remotes, and basic non-secure RF remotes, they use more or less a complex logic device, or even a real low end micro. They directly provide a signal to drive an IR LED (through a drive transistor), or gate an RF transmitter, which is typically one or two trasnistors, a coil or SAW filter, and a board or wire antenna.

In context, if you are talking of a raw IR transmitter (the logical other end of the IR receiver/decoder module) there is no ready made modules of those, I know of, as those, as said, are driven from the remote IC, in typical consumer remotes.

I do know there are "enclosed" radio transmitter/receiver modules. one could use, but typical mass manufacturers build their own "on board".

Reply to
Gary Tait

Damn, you are hard headed. You made me google for you. Feed "IR transmitter IC" to google and get this, among other things on the first page, "SDA2208-2 Siemens IR Remote Control TX/RX Driver, TV IC". Then you toss that to google.

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 JosephKK
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Reply to
joseph2k

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