Ok, so between cloud cover, burn off's, and terrible seeing, things are really starting to get out of control in the DIY factory. On a few nights recently where I thought I was going to get some imaging done, the winds bought with them all the smoke for a DFES burn off.
Disgruntled and bored, I found my self looking at my coolbox thinking of ways of making the cool down faster and the base temperature cooler, and more consistent. The rather obvious answer to that was add more amps, and with a few more trips to Jaycar and PLE had the job done. Due to the glut of 12V amps required to drive the twin 68W TEC's, I have hacked an old ATX2 PC power supply which gives me 2 x 12amp channels of nice clean juice. This also keeps my mount and camera power supplies clean from the PWM rubbish that tends to invade the the circuits of anything else attached to them.
Will test out with the camera running a normal session when the opportunity arises and will decide then on what the control parameters will be. At this stage it will most likely be a relay switching between duty and lag for each of the TEC's, with the lag TEC getting some PWM to maintain the target base temp, I hope at this stage to be able to maintain the camera body between 0 and -1 degrees on any given night. It can achieve -5.5 degree camera body temperature within 45 mins of startup. The single TEC version I was running could only achive a 5-6 degree body temp after 2 hours, and that rose steadily during the imaging session as the camera worked harder.
The box itself is a near enough copy of the Gary Honis job, I just added twin 68W TEC's ($23) (both fan assisted) and some cheap low profile 130 W CPU coolers ($34). Power supply is from the junk pile and takes about 10 mins to modify. Moisture control is lots and lots of silica gel. Cheap coldness!!
Yes...The cold finger mod isn't going well.....99, 99, 99, 99, 99 and so on...
