Many of you have probably noticed that the internal temperature sensor of the EAF is mostly useless, since it is a sensor on the die of the microcontroller in the EAF, and is not a measurement of ambient temperature -- the more you drive the EAF, the higher that reading goes.
At the same time, for many folks, ambient temperature is good enough, not needing to actually measure the OTA temperature with the external probe that ZWO sells. For those, try this hack.
Here is a photo with parts for two probes, one for a right-angle probe, the other in-line:
The little beads are 100 kΩ NTC (negative temperature coefficient) thermistors (cheap -- about 60 (US) cents a piece at Amazon). The plugs are 3.5mm TRS (tip-ring-sleeve) "headphones plugs."
The thermistor is soldered between the tip and sleeve of the TRS connector. Leave the ring pin of the connector alone since ZWO uses that for the EAF hand controller. Like so:
This is what the right angled one looks like when installed on the EAF:
This is what the straight in-line version looks like:
This is what ASICap shows:
With the external probe unplugged, EAF uses the internal sensor that shows the way-elevated microcontroller die temperature instead of ambient temperature:
Have fun.
Chen
