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Author Topic: Problem with DS18B20 sensors  (Read 748 times)
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Hi,

I have 3 pcs of DS18B20 sensors connected to Arduino with about 20 meter 3-wire cable to my DIY solar collector.

When all sensors were located onto the protoboard they worked fine and correct, but when connected with 20+ m
cable all temperature readings are all the time 0 degrees celsius?  Must be because of the distance, but how can i help it  ?
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No more problems!

Did some searching about old messages and find one advice, so i did replac the 4k7
resistor with 2k2 and now it works fine ! No more 0-values, only correct ones  smiley-cool


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Topsham, Vermont USA
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Kariky, Are the DS18B20's wired with the 3 wires as Voltage-Ground-Signal? Or are they in "Parasitic" mode?

I'd just like to know so I can help other people with this in future.   I have quite a bit of DS18B20 How-To online here:
http://arduino-info.wikispaces.com/Brick-Temperature-DS18B20

What cable are you using?? I would suggest using CAT5 network cable, which has 4 twisted pairs. I would use one pair for +5V and Ground, and the other 3 pairs for DS18B20 Signal and Ground.  That would be for the long run to your solar collector, and then break out to the individual sensors with 3-wire cable, or 2 twisted pairs. Keeping the Signal and Ground in twisted pair as far as possible would be good.

These protected DS18B20's for $5 might be good in your environment: http://arduino-info.wikispaces.com/Brick-Temperature-DS18B20#TS

Let us know how it's working...

Regards, Terry King
...In The Woods In Vermont
terry@yourduino.com

DISCLAIMER: Mentioned stuff from my own shop...
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Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

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hi terry, your online shop is very interesting, but why there is no atmega328 on site ?

plus, i do not found a page with shipping Cost, there is a page whit shipping info but no cost.
« Last Edit: August 20, 2011, 04:20:36 pm by Testato » Logged

- [GUIDA] IDE1.x - Nuove Funzioni - Sketch Standalone - Bootloader - VirtualBoard
http://arduino.cc/forum/index.php/topic,88546.0.html
- [LIBRERIA] ST7032i LCD I2C Controller Library
http://arduino.cc/forum/index.php/topic,96163.0.html

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why there is no atmega328 on site ?

Look at the page http://arduino-direct.com/sunshop/index.php?l=product_list&c=1 which has nice Arduinos using Atmel's 328 microcontroller.

And regarding shipping, for specific enquiries take note of:
"Please contact us with any questions about shipping: Shipping@YourDuino.com"
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i ask for the uP Atmel, not the entire arduino.

in the website is there a component section, with resistor, led, but not uP.
It is useful for standlone project

for the shipping question i think that it is important for a site, if it write that do not make money with shipping, create a page with shipping cost.

thanks for the answer
« Last Edit: August 21, 2011, 03:15:40 am by Testato » Logged

- [GUIDA] IDE1.x - Nuove Funzioni - Sketch Standalone - Bootloader - VirtualBoard
http://arduino.cc/forum/index.php/topic,88546.0.html
- [LIBRERIA] ST7032i LCD I2C Controller Library
http://arduino.cc/forum/index.php/topic,96163.0.html

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