PIR Motion detection
CCCC
Posts: 3
Hello All,
This is my first post to the forum and I am a rank beginner. I have a question that those with·more knowledge probabbly think is pretty simple, but here goes!
I want to place PIR's some distance from my BS2 and was not sure if i needed to boost the output of the signal in some way from the PIR. I am talking a good 40' and planed to use "sprinkler wire" to make the connections.
In some cases I would be paralleling up to 4 PIR's to sense motion in 360 degrees.
ANY advice for this beginner would be GREATLY appreciated!!!!
Thanks!!
Craig
This is my first post to the forum and I am a rank beginner. I have a question that those with·more knowledge probabbly think is pretty simple, but here goes!
I want to place PIR's some distance from my BS2 and was not sure if i needed to boost the output of the signal in some way from the PIR. I am talking a good 40' and planed to use "sprinkler wire" to make the connections.
In some cases I would be paralleling up to 4 PIR's to sense motion in 360 degrees.
ANY advice for this beginner would be GREATLY appreciated!!!!
Thanks!!
Craig
Comments
There are some from HVWTech in Canada that just indicate a 5V level on its output when it "sees" movement.
In this case, so long as you have enough voltage at the end of the wire for the stamp to determine a logic threshold, then you're fine!
I think the stamps' logic threshold is 1.5volts...but might be 2.5volts.
Other things to be warely of is noise getting on those lines.
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Steve
"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."
·· Without using shielded wire you will be highly prone to EMI noise problems.· On top of that the TTL levels on the output aren't really made to traverse that length of wire.· These are things you will have to factor in to this design.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Google "20mA current loop". This is a type of signaling that works better for long distances. A simplified version is to just put a 270 ohm resistor at the INPUT to ground. As long as the output can supply 20mA, it should work (but I don't think it is truely a 20mA current loop because the current is not regulated). You see even though voltages levels change with resistance, the current does not. So if a transmitter has a regulated 20mA output, then input will see 20mA no matter what the resistance of the wire is.
Bean.
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·
To answer a few of the questions:
1.Steve, I am using Parallax PIR's for this project. They look very simmilar to the ones from· HVWTech .
2. Chris,You are recomending that·I use Sheilded Cable. Any recomendations??
3. Bean, sometimes I have a brain f**t. do you mean for me to connect a 270ohm resistor between where the out on the PIR connects to the BS2 (INPUT) and ground?
Will this help "get the signal through"?
Thanks everyone again!!
Craig
·· I am merely providing you with some possible problems you may encounter and how you might overcome them.· That is quite a distance and quite often with long runs of wire we see people having all kinds of inconsistent results and even damage usually associated with EMI/RFI noise.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Craig