radio interference

I built a serial port temp. sensor years ago based on this fella's
work:
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And just bought kit 145 from carl's electronics:
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The unit uses DS1820 temp sensors and connects to the pc serial port.
There is a fifty foot run from the computer to the sensor.
My better half made me quit using it because of AM radio interference.
There is a constant beep beep beep.
I'm once again in need of 24 X 7 temp. logging. Is there an easy way
to salvage this unit? Or am I better off to just start over with some
sort of analog unit?
Karl
Reply to
Karl Townsend
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You could try looping the cable through a ferrite core.
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jsw
Reply to
Jim Wilkins
Start with the basics. Is the cable shielded with the shields terminated? You should be running shielded twisted pair, and the cable signal lines should be terminated at both ends. Are the circuit boards in a grounded metal enclosure? If the system is shielded, the next step will be to wrap a few turns of the cables around a ferrite attenuator core, as Jim suggests. If it were in my heart and lung machine I would add .1uF monolythic ceramic capacitors to the output of the DTS line at the computer and the input of the voltage regulator on the board. Separation of the data cable and the AM antenna will help. Running the cable close to the ground or in metallic conduit will help. An external AM antenna for the radio (away from the data line) will help.
Kevin Gallimore
Reply to
axolotl
You didnt say if it worked....assume it did....
Short of a lot of stuffing around, the clamp on ferrite interference cores are worth a try - then try if the cables you have run have spare conductors, ground them all at each end. Maybe double up on the power one on pin 8 - the thing gets its power from the receiving computer, could be a bit iffy what with voltage drop on your feed cable...
Oh, and BTW Karl - you are aware you are committing a Federal Offense by running an unlicensed radio transmitter causing interference to your wifes radio. Possibly a lot of other radios as well.. Tsk tsk......
Andrew VK3BFA.
Reply to
Andrew VK3BFA
electronics:
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Same for all those CFL users. /mark in BC
Reply to
Mark F
Buy her a bloody FM radio! Better yet, a sat radio, with none of the farkin' commercials playing all the time.
-- Threee days before Tucson, Howard Dean explained that the tea party movement is "the last gasp of the generation that has trouble with diversity." Rising to the challenge of lowering his reputation and the tone of public discourse, Dean smeared tea partiers as racists: They oppose Obama's agenda, Obama is African-American, ergo...
Let us hope that Dean is the last gasp of the generation of liberals whose default position in any argument is to indict opponents as racists. This McCarthyism of the left -- devoid of intellectual content, unsupported by data -- is a mental tic, not an idea but a tactic for avoiding engagement with ideas. It expresses limitless contempt for the American people, who have reciprocated by reducing liberalism to its current characteristics of electoral weakness and bad sociology. --George Will 14 JAN 2011 Article titled "Tragedies often spark plenty of analysis"
Reply to
Larry Jaques
Put the PC in the greenhouse as the local sensor node controller, and connect it to the house on WiFi.
Reply to
Pete C.
electronics:
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Those are not "intentional radiators".
Reply to
Pete C.
Professor Will appears to have jumped the gun. Here's the latest example:
" [R]espondents were asked whether they agreed with various characterizations of different racial groups. Only 35 percent of those who strongly approve of the tea party agreed that blacks are hardworking, compared with 55 percent of those who strongly disapprove of the tea party. On whether blacks were intelligent, 45 percent of the tea-party supporters agreed, compared with 59 percent of the tea-party opponents. And on the issue of whether blacks were trustworthy, 41 percent of the tea-party supporters agreed, compared with 57 percent of the tea-party opponents.
"The survey, which included about 1,000 respondents in six battleground states (like Michigan and Nevada) and California, found similar margins on questions regarding Latinos."
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George tends to fall in love with his own rhetorical skills and to go off half-cocked when he thinks he has a great insight. His "insight" this time appears to be that the Tea Party is the second coming of his beloved Burkean conservatives, with a strong libertarian bent. The evidence is that not everyone in the Tea Party is a racist, but that racists seem to gravitate toward the Tea Party -- something like Muslims and terrorists.
Reply to
Ed Huntress
So those who support the tea party are significantly more likely to hold racist views as compared to those who don't ?
--Wow I never would have guessed !
Reply to
PrecisionmachinisT
20 mA current loop, with shielded twisted pair. Maybe RS-485 for that distance, although I've run cat5 LAN cable 100 feet before.
The secret to minimizing interference to the radio is twisted pair and shielding. I recommend you get enough conductors so that you can also use DTR/DSR and RTS/CTS, if only for the sake of completeness.
And again, use twisted pairs and shield the cable. Ground the shield ONLY at the host end, so that you don't get a mongo ground loop.
Good Luck! Rich
Reply to
Rich Grise
Yeah, it falls into the category of whether blondes or brunettes are more likely to show dark roots. You don't really need a fancy study to know the general shape of the answer. d8-)
Reply to
Ed Huntress
Shouldn't the President of the United States be an _AMERICAN_ American?
I try not to be racist, but I hate anyone who puts another country, or a whole bloody continent, before America!
Thanks, Rich
Reply to
Rich Grise
Try harder.
Reply to
rangerssuck
Hi Karl, I've been running a 1 wire system using DS18S20s driven by a DS9097U for over three years and haven't had any AM radio interference. I am a AM radio listener with about six radios that are spread around the house. I have two bedside radios I use at night for weak signals, so if I had interference I would have tracked it down in short order. I have 13 freezers that I monitor on a real time basis, although the program I use will save and graph data. You might look up the DS9097U as a driver unit. But I think now they have went to USB connections so the numbers may change. The program I use is Lampomitari, it does exactly what I wanted but probably not the best or easiest program to use. I'll check in when I have more time to see if I can get you more info. Miikek
Reply to
amdx
No such thing, unless you are a racist.
Obama is a natural born American citizen.
Your favorite cake...
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Reply to
PrecisionmachinisT
The only American citizens who are not "natural born" are those who immigrated (legally) and then did the whole citizenship thing. Being born in another country is still "natural born" if one or both of your parents are American citizens. The "birthers" whining about this are simply morons, whether they are racist or not.
I still do not support Obummer, and I am certainly no racist. Though as a centrist I do agree with his positions on some issues, I disagree with his positions on enough issues to not be able to support him.
Reply to
Pete C.
It would be interesting if the same questions were asked about white folks. It could be that members of the Tea Party have a lower opinion about everyone. In fact I would expect members of a group that thinks the government is not hard working, trustworthy, or intelligent, would also think everyone is the same way.
Dan
Reply to
dcaster
That's an interesting thought. I'd like to see such a study, too.
Reply to
Ed Huntress
Fortunately, the serial port has slew-rate limited signals and shouldn't be an issue. The DS1820 (new ones are DS18S20) one-wire interface, though, isn't so limited. If you use twisted pair wiring, and maybe a few ferrite beads or 'clamp filter' units, it'll get better. To avoid ground loops, ensure none of the distant end (sensor) wires touch any nearby grounded metal.
Reply to
whit3rd

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