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KatyBri
06-03-2005, 10:03 AM
I need to minitor a switch closure 200' from the house. I need suggestions of what rf modules to use. The outside unit needs to be a·very low powered (preferably powered by a 9 volt battery) and hermitically sealed transmitter only. If a switch can be connected directly to the unit-great. Otherwise, I would use a Stamp. Also need a receiver in the house (connected to a Stamp 2). Anyone done this? Thanks.

Chris Savage
06-03-2005, 10:24 AM
Hello,

·· I believe this product may be able to do what you want.· Please read the documentation at the bottom of the page for more details.

http://www.parallax.com/detail.asp?product_id=27986



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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

Jay-Bob
06-04-2005, 08:55 PM
$59 is a bit expensive....

I'm a parallax fan and buying from them is great!!!

You can get transmitter and receiver chips from Digikey for a couple bucks.... That will allow you to use an alternate frequency than 433 since 433 seems to be very popular..... Linx is the manufacturer that I used, they have some great stuff......

You should be able to build the wireless path that you need for around $25 for both ends (you can use wire for antennas)...... where Parallax is gonna run you $59 per end......

These will directly interface with a STAMP (serial input\output), actually, these are the chips that Parallax build their transceivers out of....

Depending on what exactly you need... they sell an amplifier chip that I used in my bot... it will bring your signal strength up in DBs....

The Trans and Rec chips:

The manufacturers PDF files:
www.linxtechnologies.com/index.php?section=products&category=rf_modules (http://www.linxtechnologies.com/index.php?section=products&category=rf_modules)

Digikey's Price List:
dkc3.digikey.com/PDF/UK051/0476.pdf (http://dkc3.digikey.com/PDF/UK051/0476.pdf)
The Amplifier chip is $8, you only need it on the Trans side, but if you need it, it's very easy to use.......

If you want to use one of Linx antenna's:
dkc3.digikey.com/PDF/UK051/0478.pdf (http://dkc3.digikey.com/PDF/UK051/0478.pdf)

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J

Newzed
06-04-2005, 09:05 PM
Take a look at the Basic Stamo RF TWS/RSW on my webpage:

http://hometown.aol.com/newzed/index.html



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Sid Weaver
Need a bezel for your LCD?

Newzed@aol.com (mailto:Newzed@aol.com)
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Chris Savage
06-05-2005, 05:37 AM
Hello,

·· One benefit to the modules I linked to is that they're ready to go.· No need to build an amplifier, or support circuitry to run them.· Some people wouldn't know how to connect and use RC chips.· This solution offers them a ready to go alternative.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

steve_b
06-05-2005, 10:15 AM
Some ppl value their time as more valuable than spending 10hours to build or $59 to buy....

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Steve
http://ca.geocities.com/steve.brady@rogers.com/index.html
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."

Jay-Bob
06-07-2005, 01:42 PM
If it takes you 10 hours to build this circuit... then....

I'm not saying that people don't value their time, but paying more than twice as much is absolutely rediculous......

The TRX and REC are good for the distance the he quoted above, I was just noting that if you want to spread it out even further, then you could add the amp..... if you wanted to.....

The circuit is very simple.... most of the pins connect to GND...

And that is $59 PER SIDE, so we're not talking about $59, but $118........

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J

Paul Baker
06-07-2005, 08:25 PM
Its all a tradeoff, each of us value's our time differently, there are other RF modules you can purchase that are considerably cheaper. But they do not have pre-existing PBASIC code to interface with. www.sparkfun.com (http://www.sparkfun.com) has quite a few modules at different prices (and different quality), the 2.4Ghz modules for $20 apeice are in my view the best value (RF-24G). I have not interfaced with any of them, I am not aware of any other forum member who have used them, so you will be on your own developing code to interface with them (though in theory it shouldn't be too difficult a task).

Post Edited (Paul Baker) : 6/7/2005 1:31:23 PM GMT

steve_b
06-07-2005, 08:54 PM
10 hours was obviously an exageration..but maybe not....but how much time have you spent in posting these messages and researching on the net.
A quick shotgun approach would have been to go and purchase what works, rather than getting something that you then have to muscle through the code to talk to this 'new' device.

If $59 is expensive for you....I have to pay customs/duties and exchange rates! (they gov't's don't realize how much it costs to keep a sled team fed!) j/k

Of course, the other side of the ball is that you learn more by 'working thru' this sort of stuff. Depends on how badly you need to to work and when..(now?)!!
IF I apply what I'm paid at work to the amount of time I spend on building my own circuits, I quickly surpass what it would have cost to just buy an off the shelf item.
however, There is a sense of accomplishment in doing it yourself!
To each their own!

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·

Steve
http://ca.geocities.com/steve.brady@rogers.com/index.html
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."

Chris Savage
06-07-2005, 09:25 PM
Hello,

·· I think the topic has gotten lost in the debate.· Perhaps the best we can do is provide our best answers and information and let the person asking for it make their decision based on that information.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

Ken Gracey
06-08-2005, 10:59 AM
Dear KatyBri:

For detecting switch closure, I'd recommend the following two products from Parallax:

http://www.parallax.com/detail.asp?product_id=27996 (http://www.parallax.com/detail.asp?product_id=27996)·Transmitter - $39
http://www.parallax.com/detail.asp?product_id=27995 (http://www.parallax.com/detail.asp?product_id=27995)·Receiver - $59

Even cheaper is that you could hack the Key-fob unit and connect it directly to your switch:

See http://www.parallax.com/html_pages/products/communication/rf_modules.asp (http://www.parallax.com/html_pages/products/communication/rf_modules.asp)·and your cost for the keychain transmitter is $20 and receiver is·$69.

I would also look into getting a pair of mini ZigBee radios. I've seen many mini evaluation modules at trade shows which the sales people say sell for "just twenty bucks".·Not sure how many thousands you need, but these are starting to make their way into hobbyist hands.

It's not $59 as suggested above, for each module (a total of $118). And everybody is correct - there's always a cheaper way! No matter what you want to do, there is going to be a cheaper solution. I bet you could get this done for $15 if you look around enough, surfing eBay and visiting surplus stores. Jay-Bob's approach is fine but it depends on the budget and time you have allotted to the project, as others have more eloquently identifed. And there's the "opportunity cost" as economists call it. This is the lost income/opportunity from doing something you don't do efficiently·considering you might have higher·output while spending your time in a capacity that generates personal income. Then again, if it is strictly for hobby then·this argument holds no water. Then you can waste all the time you want.

Ken Gracey
Parallax, Inc.

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