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Have started thermal testing of the new heatsink/fan combo for the mono camera. Heatsink is the Coolmaster Geminii M4 Low Profile but I ditched the awful fan it came with and stuck on a Noctua NF-F12 Industrial fan which will run at 2000rpm. The fan is setup to push air through the heatsink, so it's pushing towards the TEC but this is probably optimal for this fan, which has great push but would not be as good as a pull type. In the final config on the camera the TEC is backed with the carbon fibre bracket so pushed air will deflect off that much like it did off the counter in the photo.
The test jig was put together with a Jaycar 51W/6amp TEC (same one used on the colour camera), and a single 40x40mmx1.2mm copper backing plate on the TEC cold side to simulate a cold finger. This arrangment was sandwiched together with Coolmaster thermal paste and clamped with cable ties. A temperature sensor was taped to the rear of the copper plate and a piece of insulation foam placed over that. Photos of the test rig are attached below.
It was all wired up to my temperature and PWM control box that I use for the colour camera. Room temperature was 24C during the test. On power up the test plate temperature dived quickly to below 0C and stopped at my normal setpoint of -5C. I reset the setpoint for -10C and it moved down to that and stopped. I reset the setpoint again to -15C and it took abit longer but eventually (within three minutes) reached it and held steady. The hysterisis around the setpoint was greater than normal but there was less copper mass attached as a finger, and less insulation.
So that's a Delta T of -39C not bad at all, however, measuring directly on a the small copper plate behind the TEC cold plate is always going to show a good result. I won't know definitively until the cold finger is tested in the camera.
Photos attached.
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