Pantera DeTomaso Temperature Gauges
Figure 3 – Original 230F Temperature Gauge Performance
The 230F gauge is pretty accurate around 90F. But, from around 122F (50C) to 230F – it reads low by 15 to 20 degrees. As an example, the original gauge reads 230F with 14 ohm resistance across the sensor.
To show a 14 ohm resistance, the sensor has to be at just over 250F.
OK, so let’s add a 10 ohm resistor. For the gauge to read 230F the resistance across the sensor would have to be 4 ohms (14 needed for the gauge to read 230 – so, with 10 ohms from the resistor, the probe can only provide 4 ohms). Wow, now the sensor has to be up around really hot to get the gauge to read 230F.
The impact of the resistor is much greater at higher temperatures. In comparison, at 122F, the gauge needs to see 88 ohms across the sensor, which means the sensor needs to be at around 140F. Add a 10 ohm resistor and the sensor needs to be at around 145F.
Directionally, the 10 ohm resistor is not helping, but it does make the gauge display a lower temperature. Not a correct temperature, mind you, but a lower temperature.
The temperature/ohms response of the 260F eBay gauge is shown on Figure 4.
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