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Dew prevention: Consists on a CNC milling  aluminum frame with an optical glass window installed on it, the glass heats up thanks to the camera body chassis, the air-spaced camera between the CCD sensor and DSLR chassis, once installed is airtight, this completelly grants dew prevention on any ambient if the DSLR is on Stand-By. Previous tests made with electronic resistors arround the CCD surface to heat the glass had no success because the CCD sensor heats up a lot if we want to prevent condensation on hight dew point ambients, cause to be suspicious on other modifications that incorpore this system.
                    PELTIER EFFECT COOLED NIKON D40, D40X, D60, D3000 One of the problems of taking digital astronomical pictures is the noise caused by sensor heating, it takes heat from itself working current and from other circuits and mechanisms of the camera. The making process is the same for the Nikon D40X, D60 and D300 and sightly different for the Nikon D40 due to its CCD is a different model, so it has different size and pins distribution.
CCD sensor and electronics board disassembly: Nikon D40X, D60 and D3000 incorporate the Sony SuperHad ICX493AQA 10 megapixel CCD sensor, used too in astronomy cameras like QHY10, ALCCD10, TRIUS SX-26C. Nikon D40 incorporates a Sony SuperHad ICX453AQ 6 megapixel CCD sensor, used too in cameras like QHY8, ALccd6, Starlight Xpress SXVR-M25C
Extracting the CCD sensor from its chassis with a CNC milling machine
Copper sheets CNC milling and temperature sensor insertion The new copper chassis has two insertable pieces tin filled, the central cavity is where the NTC temperature probe is installed allowing a precise and reliable temperature measurement of the CCD sensor. Some mods hide this detail: depending of where the temperature probe is installed and the quality of the thermal contact between the CCD sensor and cold finger it can get much different results in temperature measurement. A deficient thermal contact of CCD sensor and a bad placed temperature probe will cause the temperature probe cant get hot from the CCD, but be cooled by the cold finger and give a non reliable measurement.
CCD sensor housing and holding, air chamber detail. Peltier module and CCD sensor are holding with a thermal epoxy compound that grants a very good thermal transmission and a strong holding, the air chamber transmits heating across the cold finger by contact and by air convection too. A PVC frame arround the CCD and some grease on installation holes will grant air tightness once installet on camera chassis.
Final assembly The cooling module horizontal axis is assembled into the DSLR chasis with it original 3 screws and some grease and insulating tape that grants airtight of the cold finger, tyhe cooling module vertical axis is atached to the DSLR body chassis with a thin layer of polymer adhesive that can be cutted easily on the hipotetical case on DSLR body fails, so the cooling module can be installed on other Nikon compatible camera body like D40X, D60 and D3000. Both combinations of axial and radial atachements grants an strong assembly of the cooling module and reduce vibrations.
Electronics Both cooling module and camera funtions are powered throught the same DC Jack 5,5x2,1mm, camera`s mainboard USB conection has been placed onto external electronics and added a Canon C1 type external shutter connector (like stereo audio jack 2,5mm female), so we can control the shutter and BULB mode throught any Canon C1 compatible intervalometer or computerize shots at diferent exposure times and ISO speeds with a DSUSB adapter and astronomical software like MaximDL, DSLR Shutter, Nikon Camera Control Pro and others. Once the power cord is plugged the camera funtions will work throught an internal voltage regulator that automatically charge the camera`s battery if necesary, there is no problem of battery discharging or overcharging. The front power button of the external electronics works only to power on/off the cooling module, so the camera can work too with the cooling module off. The temperature hand controller has many programable functions like temperature selection, max/min temperature limit, histeresis regulation and more. Temperature histeresis regulation ajusted to 0,1ºC grants the selected temperature at +/- 1ºC of desired. Power comsumption at 100% of time cooling dont exceed 3 amperes conected to a 12VDC sorce including the camera electronics taking long exposures continously.
Detail of some of the pieces used on this modification, designed on Corel Draw layer by layer. Once exported to DXF format we can edit them on the CNC software to make the process program.
Detail of where to install the temperature probe to get a reliable temperature measurement
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