HB temp sensor in water

I have a couple future applications where I am going to be monitoring some water and soil temps in a green house.

Anyone ever take one of the simple HB temp sensor kits and put the DS1820 at the end of a wire instead of mounting it on the board?

I am thinking that instead of trying to water proof the board and the lan cable, just water proof the sensor on the end of a 3 wire cable and then the sensor can be submerged in the water.
The board can sit next to the water tank.

Any reason the Ds1820 can't be located off the board, say 12 inches or so?

Thanks for any info
Doug

EL34 said:

I have a couple future applications where I am going to be monitoring some water and soil temps in a green house.

Anyone ever take one of the simple HB temp sensor kits and put the DS1820 at the end of a wire instead of mounting it on the board?

I am thinking that instead of trying to water proof the board and the lan cable, just water proof the sensor on the end of a 3 wire cable and then the sensor can be submerged in the water.
The board can sit next to the water tank.

Any reason the Ds1820 can't be located off the board, say 12 inches or so?

Thanks for any info
Doug

Click to expand...

This is the way I have all of my sensors mounted. They work perfectly mounted directly to cat5 wire.

Ah, ok, thanks for the info

Are you using any type of circuit board or just attaching a DS1820 to the end of a network cable?

I was curious if I could just use have just a DS1820 on a wire and whatever few parts it takes to get it to work.
I have several HB sensors and a rainwise gauge on my system attached to the house.
I am going to be branching out to my greenhouse soon for some controls like controlling a solar water heater, turn exaust fans on and off, sensing soil temps, etc.
thanks for the info

Rupp said:

EL34 said:

I have a couple future applications where I am going to be monitoring some water and soil temps in a green house.

Anyone ever take one of the simple HB temp sensor kits and put the DS1820 at the end of a wire instead of mounting it on the board?

I am thinking that instead of trying to water proof the board and the lan cable, just water proof the sensor on the end of a 3 wire cable and then the sensor can be submerged in the water.
The board can sit next to the water tank.

Any reason the Ds1820 can't be located off the board, say 12 inches or so?

Thanks for any info
Doug

Click to expand...

This is the way I have all of my sensors mounted. They work perfectly mounted directly to cat5 wire.

Click to expand...

EL34 said:

Ah, ok, thanks for the info

Are you using any type of circuit board or just attaching a DS1820 to the end of a network cable?

I was curious if I could just use have just a DS1820 on a wire and whatever few parts it takes to get it to work.

Click to expand...

Yes you can connect a DS18S20 directly to the wire without using one of our boards. Our boards just make it easier to add a sensor to a 1-Wire network.

Eric

Thnaks Eric,
I have a bunch of your boards for my weather station, but I think this application may call for a simpler set up.
Especially since I can easily see maybe 6 or more temp sensors being needed and most of them will be in water or in wet soil.

I'll dig into the hook data for the DS1820.
I didn't check, but do you have a simple hookup schematic for the DS1820?

edit: I was reading the data sheet on the dallas site.
Looks like I can run a Ds1820 with just two wires in parasitic mode?
Ground tied to pin 1 and 3 - tied together
Data out to pin 2

But, I have one of your 6 channel master hubs, I guess it is feeding VDD out to all my sensors?
Any hookup info is appreciated.
I'll have to get a bunch of sensors from you once I get the wiring figured out.
thanks Eric

You can hook the DS18S20 up parasitically even using our Master Hub or you can use the supplied +5V to power the sensors. If you need more hook up help just let me know.

Eric

EL34 said:

Thnaks Eric,
I have a bunch of your boards for my weather station, but I think this application may call for a simpler set up.
Especially since I can easily see maybe 6 or more temp sensors being needed and most of them will be in water or in wet soil.

I'll dig into the hook data for the DS1820.
I didn't check, but do you have a simple hookup schematic for the DS1820?

edit: I was reading the data sheet on the dallas site.
Looks like I can run a Ds1820 with just two wires in parasitic mode?
Ground tied to pin 1 and 3 - tied together
Data out to pin 2

But, I have one of your 6 channel master hubs, I guess it is feeding VDD out to all my sensors?
Any hookup info is appreciated.
I'll have to get a bunch of sensors from you once I get the wiring figured out.
thanks Eric

Click to expand...

I get a higher temp reading range using the +5 from the hub right?

The top of the green house sees 100+ easily.
I saw 130 degrees F the other day.

I have to turn on a vent fan at a certain temp using the one wire sensor and X10 powerline commands.

The temperature range is the same whether the DS18S20 is parasitically or externally powered. But 100+ F is no problem since the sensor can measure up to 257 F

Eric

EL34 said:

I get a higher temp reading range using the +5 from the hub right?

The top of the green house sees 100+ easily.
I saw 130 degrees F the other day.

I have to turn on a vent fan at a certain temp using the one wire sensor and X10 powerline commands.

Click to expand...

Ok, thats great.
I thought I read something on the maxim site about higher readings are possible when not using parasitic

Maybe it was more stability?

anywho, I'm gonna grab about 10 of the temp sensors from your store and start the experiment

Now that wserver is workinmg again that is.
I use Wserver to read all the sensors. It creates a text file for each sensor on the one wire lan which can then be opened by my programs.
Once I have the data in my program, I can turn on and off x10 devices like fans, pumps, etc
It's easier than trying to hack into the one wire with the SDK and get readings
plus I also create graphs with the Wsaerver text file data.

From the DS18S20 sheet:

The use of parasite power is not recommended for temperatures above 100C since the DS18S20 may not
be able to sustain communications due to the higher leakage currents that can exist at these temperatures.
For applications in which such temperatures are likely, it is strongly recommended that the DS18S20 be
powered by an external power supply.

Good catch. I had quickly read over the data sheet again but completely missed that.

Eric

sda said:

From the DS18S20 sheet:

The use of parasite power is not recommended for temperatures above 100C since the DS18S20 may not
be able to sustain communications due to the higher leakage currents that can exist at these temperatures.
For applications in which such temperatures are likely, it is strongly recommended that the DS18S20 be
powered by an external power supply.

Click to expand...

I knew I had read something, just didn't remember what it was. LOL

Ok, I ordered 10 of the DS1820 temp sensors from Eric so I can start this project

I have a couple hundred feet of cat 6 wiring left over that I plan to use to connect the house and the green house.
cat 6 is kind of over kill but I can use the extra wire pairs for something later.
My 6 channel master hub can send power on the cat 6 so I don't have to use parasitic mode.

I plan on using a common screw terminal block in the green house that the cat 6 from the house goes to.
I don't really need to have rj45 jacks on all the temp sensor cables.
I don't plan on using lan cable for each of the temp sensors in the green house.
I have a spool of very small diameter 3 wire shielded cable on hand here.
I can just branch off the screw block terminal using the 3 wire cable for all the temp sensors.
The temp sensor lengths won't be much over 10 feet.

Anyone see any problems with this idea or have any suggestions?

If you keep the branches pretty short (less than a meter) you shouldn't have any problems but with branches like that you can get reflections that can cause the 1-Wire network to quit working. The best way to see if it will work for you is just to try it and see what happens.

Eric

Sounds good, that's what I'll do