electrical gizmos for temperatures...

Discussion in 'Homesteading Questions' started by crwilson, Mar 21, 2005.

  1. crwilson

    crwilson Well-Known Member

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    hey folks does anyone have or know of a thermometer type unit that can be hooked to your computer to keep track of temps during the night and day? thanks
     
  2. Phantomfyre

    Phantomfyre Black Cat Farm Supporter

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    Sorry, I don't, but what a nifty idea! I know you can get high-low thermometers that record the high and low temps of a given time (until you reset them) so you could just check it and record every day, but nothing that actually feeds automatically into your PC.

    Diana
     

  3. Quint

    Quint Well-Known Member

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  4. backtobasics

    backtobasics Member

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  5. mikell

    mikell Well-Known Member

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    I have a multimeter that has an rs-232 hookup to a computer it was about 50$ and it has a temp input. I have no idea where I got it I'll look .


    mikell
     
  6. mikell

    mikell Well-Known Member

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  7. crwilson

    crwilson Well-Known Member

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  8. mikell

    mikell Well-Known Member

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    The only complaint I have with the unit is you have to shut it off meaning it will nit shut off automatically but then if your taking data you don't want it to shut off.


    mikell
     
  9. paden

    paden Well-Known Member

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    Radio Shack used to have a weather station that you could plug into your PC. Not sure if they still offer it. It was spendy though.
     
  10. mikell

    mikell Well-Known Member

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    Crwilson wondering what your application is. Indoor outdoor?? I used that unit to set up my brooders and their backups before I put pheasants in.

    mikell
     
  11. cookcooks

    cookcooks Member

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    We had a neat one that measured everything and kept the information so you could get your monthly/yearly/daily average of humidity/rain/wind/temp we paid about $500 for. Our problem was that here in Florida the static electricity in the air during our frequent storms would shut the unit off and it would lose all of it's info. During the summer they are almost daily but very short.

    We did have it grounded but it was so sensitive that didn't help. I am just telling you this so if you get one and you have the same problem it is not how you have it hooked up, it is the unit. They might have fixed it by now, it was a wonderful machine!
     
  12. Cosmic

    Cosmic Well-Known Member

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    Yup, I did the development of such a critter way back when. Basically is a thermistor network that changes resistance with temperature change. You can read them via the gamecard. I designed an input box that allows reading four analog and 4 contacts. Very accurate, there is a procedure to calibrate the gamecard and a program generates a lookup data file that converts it to temperate either C or F, based on the exact parallel resistor value used in the network. Will read accurate to 1 degree F across the entire range. Basically you need a user program that looks at a particular gamecard channel, gets a STICK reading and converts that to temperature based on matching data in the lookup file. Frequency of readings is up to the user program. Typically you take a reading every minute or so.

    That was just part of an entire package that I developed for home automation and monitoring / control. I sold it for years. Still have some of the sensors left. I did temperature, humidity, visible light and most of the weather stuff like wind direction, speed, rainfall, etc. System runs in DOS and can do X-10 along with a parallel port in / out control of usually relays.

    The thermistor method is very stable but requires a super amount of engineering work. They are non-linear and lots of compensation is required at both ends of the curve. These can also be read via a computer using a BASIC Stamp computer as the front end data acquistion device and coming in via the serial port.

    Everything is packed up. I am in the process of moving to Ohio. Should be there in about a week. That system was called AUTOMATE and was sold via a shareware demo and information program that detailed what and how things were done. IIRC last issued version was 4.5. Sold a lot of it in the 90's. I have nothing available right now. Everything is in boxes, should be loaded on the truck tomorrow. Don't even have any of the software on these newer computers.

    You can also use a data acquistion system known as DHR as the front end. Those can read RTD's or thermocouples or you can do a conversion with a interface module and get the thermocouple temperature as a 4-20 madc signal with something like a B&B Electronics module. Then can read that as a voltage with a number of input methods. A lot of those methods if done on the cheap drift like crazy / are impossible to calibrate. Many, many ways to get a temperature reading. The best are probably those data acquistion modules pre-calibrated to some particular sensor. Not cheap but fairly foolproof. The DHR ones are designed to work using an ASCII Comm command scheme.

    My stuff was super cheap way of doing automation, maybe why people loved it. I use a very old Point of Sale computer called a IM-40 by Epson as the control machine. They are still available. Will just about fit in a shoebox. 486, 33 MHz. Very well suited for the task.

    Back when I was a working slug, was a instrumentation and controls engineer. did the big things, like power plants, pulp and paper mills, major industrial plants, so all this measuring stuff was an offshoot of what I had done for years. Plan on automating the house in Ohio, maybe a little more than the house I had here in Boston.