Radio Shack Digital Thermometer Probe

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Here is a picture of the thermometer just opened. As you can see there is not much to these things:

Open

This is a picture of the circuit board unscrewed from the case:

Out

Inside the large red oval is the back of the LCD display and inside the small red circle is the internal thermistor. The outdoor thermistor is obviously the end large white cord with the metal clip on it.
This is just an upclose picture of the circuit board:

Back

Here is a picture with everything completely out of the case:

All Out

The internal thermistor is again circled in red. This is a picture of the circuit board with the indoor and outdoor thermistor wires removed from the circuit board. I had an old one of these thermometers that was trashed, so I have 2 small thermistors (internal) to use (one from the old one and one from the new one).

PCB

I did not want to use the larger outdoor thermistor that was already attached, but you can if you want to. The 2 red circles are the spots where you need to solder the new leads. The top one is the “outdoor” and the one on the right is the “internal”.

Here is a picture of the 4 leads soldered on with a truck load of hot glue to hold the wires in place:

Glued

Now it’s ready to put back into the case:

Done

Here is a comparison of my buddy’s thermometer (front) and mine:

Comparison

I did improve on the variance between the 2 thermistors and actually did not change the temp reading that much – I thought that 5 ft. of 26 gauge wire would have enough resistance to mess with the reading, but not by too much.

Probe

Now I have a probe right above the CPU core with a hole bored into the heatsink base and one on the back of my Asus Geforce3 Pure video card.
I have it sitting right by my monitor so I can keep a close eye on the temps.

Hope this will save you some $ and still give you peace of mind knowing you’re not frying your CPU (never trust onboard thermistors). My next project will be to use Radio Shack’s talking indoor/outdoor thermometer.

(You can also comment on this in our Forum).

Bryan Heestand

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