Gina

Cooling on Low and camera temperature 19°C. It reached around 40°C in sunlight without cooling.

Daytime image (just captured). Exposure 32µs and gain of 0. For nighttime when fully dark I use 60s and gain of 102.

Cooling to -11.7°C in spite of a high ambient temperature.

Nearly dark and seems alright. 60s exposure.

Refocused and replaced cover with dome. Focus changed a bit with the dome. ASC now back on observatory, all connected up and working. Just waiting for dark to see if I've cured the problems. The current reading on my power distribution box confirms that both TEC and dew heater are drawing current. 2.5A TEC and 1A dew heater, total 3.5A.

An earlier ASC looked like this. That was alright until a storm ripped it off the obsy roof and spread the contents far and wide!! Got the Passive Cooler from Amazon. They're now black anodized, mine was ali coloured.

This is something I considered for cooling the hot side of the Peltier TEC. It uses purely convection cooling (or if outside, wind if there is any).

That sounds sensible. Only do what you feel comfortable with - it's all for your own enjoyment, after all.

You don't need to use USB3 for an ASC - USB2 is fine. That's what I'm using. The only advantage of USB3 is a shorter download time. With an ASC you will probably use an exposure of 60s for nighttime when it's dark. A few seconds download time is no problem. You can go up to 5m with USB2. In daytime you will want to use the minimum exposure of 32 microseconds, but still not want to image more than once or twice a minute. I have my ASC mounted on an aluminium pipe on a bracket on the north wall of the obsy roughly NW of the pier where I tend not to image much.

As you know, I'm using an RPi right at the camera thereby reducing the USB cable to almost nothing and needing only power connections. I have all the info on this including step-by-step instructions. But whether anyone follows my example is entirely their choice, of course.

I'm inclined to agree that a waterblock is almost certainly overkill. When I decided to water cool, I was using a different, less sensitive camera. I'm even considering redesigning my ASC and making things simpler. OTOH I have all the water-cooling kit so might as well use it.

Connected the dew heater across the Peltier TEC connections and put some black goo over the red LEDs. Next to put it all back together and see if I can get sharp focus on distant trees. Then put the cover back on and check that the image is still in focus with the dome on.

Cleaned the dome with water and it's nice and clear now. Next to the dew heater. Looks like the IRLZ44N has failed from testing with DMM. Thought I had some but can't find any. Looked at buying some but several days delivery. The IRFZ44N is also suitable for this application as there's plenty of voltage available and these are both cheaper and shorter delivery. Ordered some with delivery by Tuesday 2 June. Meanwhile I could connect the dew heater in parallel with the Peltier TEC to get it working.

Haven't considered running a Peltier TEC off a battery (other than something like a car/caravan battery). I have cooled the astro camera in my ASC - an ASI178MC, using a good quality Peltier TEC - Peltier Module, 54.6W, 4.4A, 20V, 40 x 40mm. Running this off my 13.8v main observatory supply and using water cooling of the hot side, I can get the camera temperature down to -12°C with an ambient temperature of 15°C. The TEC draws around 2.5A.

So far the colour change desiccant shows that no moisture entered the ASC casing.

Now have the ASC complete with mast indoors. There is muck on the outside of the dome as can be seen here. Just hope that when I get the dew heater working and no dew on the outside of the dome that this doesn't happen again. I didn't get any muck on the lens when I was using it uncovered overnight.

Now it's almost dark I can see all the things that need fixing!! Latest is that the power LED on the RPi is illuminating the dome! Dew Heater Focus Looks like a hair on the lens

The focus isn't good either. I may have to arrange remote focussing like I have on my main astro imaging kit.

Dew heater isn't working. I'll sort it out tomorrow. I've turned the cooling off and hoping the heat from the camera and RPi etc. might warm the dome.

Wiring finished, parts assembled and attached to the mast then mast attached to north wall of the observatory. Power cable run to the power distribution box in the warm room and water circulation arranged. The camera sensor temperature started at 26°C but with the Peltier TEC cooling and water cooling of the TEC hot side the camera is now down to -12°C. Here is a screenshot of KStars/Ekos running the ASC.

Shocked to read about your accident Chris! Hope you are not in too much pain and get better soon. Take care.

Been doing more wiring up on the ASC. I reassessed the power requirements and realised that the 5v load was more than I had originally catered for. An RPi 3B+ takes up to 2.5A and the Peltier TEC on LOW (5v) a little under 1.5A. The buck converters are rated at 3A and not sufficient for the possible 4A so I need 2 - one for the RPi and the other for the TEC. I now have two buck converters wired in.

A new version with shorter exposures and a processing parameter in PI adjusted giving increased dynamic range. Rotated to put north at the top.

Night view. Focus isn't bad. Sensor temperature is 16°C but not showing hot pixels all that much. I'm wondering if I might have "over engineered" the cooling as this is with only ambient cooling on the open case.