Reverse engineering a IR thermometer LCD

Hi…i am a new user here. It looks the probe was grounded to the battery negative terminal of the thermostat, if I take it off it goes out of control. So I am assuming its grounded properly hopefully.From what I read a lot of these static LCD’s uses different voltages, could this be why the wave is messed up?

Hi,

I’d like to note that in the newer model of this thermometer pin 3 and 4 appear to be shifted to pin 2 and 3. So D5/4/7/3 is controlled by pin 2 instead of 3 and D6/1/2 is controlled by pin 3 instead of 4.
Also if you’re hooked up to an arduino mega the comparator pins should be 5 and 1, as the mega’s comparator uses different pins as the nano’s.

Huge thanks to Derryn Harvie for describing the basics of this decoding script.

Hi…simply measuring the voltages at the various pins you list will reveal at least ONE pin that varies with the change of signal. Measuring that and applying a test signal from known temperature sources to achieve some sort of calibration.
The pinout of the op-amp will reveal the power connections, the yellow wire may be the laser diode on/off signal, the green may be the amplified signal from the IR receiver diode.