Y'all know I am the DIY fanatic, why buy it when you can make it.
Picked up a 40mm square 50 watt peltier module, $8:50 ( I'm also cheap !
).
Idea was to cool the AS120mc down a bit for longer exposures. Managed to sandwich the module between the camera and a big CPU heatsink. I hacked all the bulky heavy metal off just leaving the thermo pipes and the fin array to keep it all lightweight. The Peltier was in direct contact with the copper base plate and a lot of silicon paste. Tested on the bench with 5 volts and it was all working so loaded it onto the Lunt and powered up the laptop so I could connect and read the chip temperature. The camera was in a neoprene sleeve to insulate it.
At 5 volts it took about 30 mins to cool the camera down by about 8* below ambient (17* at the time). The fins were definitely warm but quite within limits. Ran some 30 sec dark exposures ( raining outside ) to look at noise. Seemed to be taking a long time to lower the temp and then I figured out that via conduction it was attempting to lower the temp of the whole focusser assembly through the 2" to 1.25" adapter. So first mod to work on is to isolate them with a plastic sleeve or and plastic adapter maybe.
Upped the voltage to 12v and the camera rapidly shot down to almost zero with quite a bit more heat coming off the fin array so plenty more oomph left in the system yet. I called it quits after about 10 minutes because I was concerned that the heat load from the scope would be too much to protect the peltier.
So next step is to isolate the camera from the scope conductively and although the neoprene sleeve for outer insulation seemed quite efficient I'd improve on that as well.
I got condensation on the camera window, not sure if it was inside or outside ( very damp rainy day ) but I need to address that as well.
I believe that with a little more work I can get delta of at least 25* or better below ambient. Note that todays experiment was without forced cooling by fans or coolant and even at 12 volts I could still place my hands on the fin array and the copper tubes near the base plate were hot but not unbearably so.
Anyway here's a pic of the setup. Note there is very little weight in that array of fins.
Only thing I forgot to do was to upload the darks off the laptop to take a look at the noise ... oh well, tomorrow will do
