Remote RH Sensor

OK, so I've seen that alot of people are purchasing $20-30 weather stations at Walmart and such, and asking why it only reads 40% RH or something low for what it should be in their terrarium. The reason for this is that the remote sensor on these is ONLY for outside temperature. It seems that the ones with remote RH sensors are more pricey and are a little more difficult to find. This leads people to just chunk the whole thing in their terrarium only to find out the unit itself isn't waterproof and now its broken So, I decided to do a writeup of how I modified my Springfield Precisetemp to include a remote RH sensor.

Supplies:
1) Weather Station
2) Small phillips screwdriver
3) Soldering iron and solder
4) Wire
5) Heat shrink tubing

OK, first you need to pop out the screws that hold the unit together. On mine there were 7 screws; they had a standard phillips head (yours may have a small torx head, just use the right tool for the job):

Be careful when you're pulling it apart. If you feel that there's too much resistance somewhere, DON'T FORCE IT! Inspect it again to make sure you've gotten all the screws. Check under the battery area and see if there's any screws under there as well. There are sensitive parts in there, you don't want to break anything.

Next you need to find the RH sensor. Look on the casing for the unit and there should be a couple holes pretty close to it to allow air in. In the price range we're working with here, most of them should be the same type pictured here:


What you'll want to do is cut the leads at about the halfway point. Be very careful, as they have a low tensile strength and will break easily. Also they will most likely be exposed leads like mine, so make sure you mark them somehow so you can remember which wire will go to which lead.

After you sever the sensor, you're going to solder in a length of wire in order to make it external. I suggest using the wire from an old DC converter (like a phone charger or something) that has 2 distinct wires that are bound next to each other. Split the 2 wires apart from each other at each end about 2-4 inches down, so you've got room to work with individual wires. Take a piece of the heat shrink tubing and cut 2 pieces about 1/2"-3/4" each. You'll need to slide these over the split wires BEFORE you solder the sensor on, or else you won't be able to get them on there. Now solder a wire to each lead on the sensor, then slide the shrink tubing up and heat it with a lighter to seal off the contacts:

Sorry that pics kind of crappy, but you get the idea. Also sorry I don't have any pics of the actual soldering process.

Next solder the other end of the new piece of wire onto the exposed leads on the unit. This is where you'll wish you had marked them somehow if you didn't. After you have it solid, just cut a notch in the case for the wire to run out of and BINGO, you've got a remote RH sensor! Here's mine fresh out of action for a pic:


This particular model was found to be pretty accurate by testing it with a psychrometer. I've been using mine this way for about 6 month without a hiccup. Anyway, hope someone found this useful! Lemme know what ya'll think, and feel free to deviate a little bit if you're comfortable... I know how everyone thinks around here

GL Everyone

by NeedMoreSleep