This tutorial is compliments of Chuck Coleman ... Thank you Chuck !

Setting up the sensors for the Weeder board

I have set up my home with Ethernet wiring on the T568b protocol.

John's Closet at is a great resource for this information.

Go to the link at for the wiring set up that I have used.

The T568b is the most common. You can use CAT 5 or CAT 5e. If you are going to pull wire then by all means go with CAT 5e which has a different twist in it that will allow the use of Giganet speeds. The sensors don't know the difference.

The reason that I have picked the wiring colors that I have is that once the sensors are made then you can use any Ethernet outlet to plug them in and not have to run any additional wire. These wires are not being used in the Ethernet network and will run fine even if you are using the same line for networking.

Some modification might have to be made at the computer end to get the correct wires to the Weederboard. With a little forthought this should be rather easy to do and save a lot of hassle with pulling more wire.

I suggest that every sensor be made with the advanced circuit in the tutorial. This will assure accurate reading most of the time. I have one sensor that has a run of 100 feet and it is giving consistent readings over that distance. There will be some erroneous reading from time to time and I suspect that static electricity has a role in that.

Also making all the sensors at one time is better than doing them one at a time. Some consideration should be made as to how many sensors you will need. I also suggest making a few extras for backups.


LM34 sensor.
These are made by Texas Instrument and come in a variety of specifications. Go to for more details.

The indoor sensors are the cheapest and the one with the widest range for extreme temperatures are the most expensive. Pick the one that right for you.

IMPORTANT: Make sure that you mark each sensor with the range if you use more that one type on sensor. This will prevent getting them confused and having an indoor sensor trying to measure -40F.

0.1 mf capacitor
1.0 mf capacitor of the canister type

Capacitors have polarity so make sure that the correct leads are soldered to the correct wires.

75 ohm resistor

Various sizes of shrink tubing
( I always use 3M. It is far better than most of the other stuff out there.) Also get different colors that will match the color of the place you intend to place the sensor.

Since you will be putting a final long piece of shrink tubing over the who sensor this is the color of the final product so it doesn't matter what the underlying colors are. You can use electrical tape of course but shrink tubing is so much easier to use and prevents moisture from corroding the connections. It also has more of a finished look of a professional product.

Solder and soldering iron.

Some sort of mutimeter that will test continuity.

2 heat sink clips to prevent components from getting to hot. Radio Shack has them for a few bucks.


The images are self explanatory. It is important to test the continuity of each step to make sure that there is not a bad connection in the circuit.

Once the capacitors are in the circuit you will need a AA battery to test the circuit with a volt meter. Just connect the battery on the ground and power and give the capacitor a few seconds to charge and then measure to see that you have power throughout the circuit. There will be reduced power through the resistor so any current will show that the circuit is complete.

At each step consider where you will have to put on shrink tubing before soldering. Then move the shrink tubing down the wire to the soldering joint. Test the tubing to make sure it will go over any components before soldering. As always use the smallest size of tubing that will fit over the component. You will find that this is easier said than done and some forthought is important to prevent having to re-solder components because there isn't any shrink tubing.

Once the sensors are done you can put an Ethernet plug on the end and plug it into the network anywhere there is an Ethernet outlet. If it is already used then this will involve taking out the wall plate and hacking into the wires and adding another outlet. This is of course dependant on your skills at modifying the wiring. If this makes you uncomfortable then this should be left to someone that is skilled in this type of work.

And here are the pictures referenced above :

Break out box connectors
Endpoint LM34 diagram
LM34 wiring picture
LM34 wires and shrink wrap
LM34 wires and capacitor
Capacitor and Resistor
LM34 wires, above Cap and Res
Everything in the shrink-wrap