[rcheshire (Rowland)]

The test set-up is an internal TEC constant at 1.2v and an external TEC rated at 12v 6A. Heat sink as in previous post

Rounding, I found that the temperature differential, starting at 8 volts increased by 1C/volt. A 3 minute exposure at each voltage increase, decreased the differential by 1C. ( an acceptable mismatch and manageable with dithering).

The first image compares performance without cooling and temperature rise measured at the bottom left corner of the sensor frame over 240 seconds.

A graph showing temp differential vs voltage and 3 minute exposure effect.

Noise comparison from PixInsight Noise analysis script and noise evaluation during debayering.

EDIT: It crossed my mind that a two TEC arrangement (not stacked, which is usual) has advantages over a single brute force external TEC (which can achieve moderately higher temperature differentials) because the metal in the vicinity of electronic and mechanical components is warmed by the hot side of the internal TEC.

In this installation, the hot side of the TEC is immediately adjacent to the face of the sensor and the rim of the chassis which surrounds the sensor face. There is also a small air gap between the chassis and the sensor.

The Astrodon filter is clear of condensation at -3C, measured at the bottom left corner of the sensor frame. Unfortunately Backyard EOS is not recognising the camera, which prevents reading sensor temperature.

An essential component of cold finger installations is a metal collector plate (practically speaking, the bit that clamps the TEC to the heatsink) on which ice and dew forms, keeping the internals free of the same. This was observed by another DIYr, and given 4 different conversion styles to date, it seems to be correct.