Gina

Well, it's a more suitable size and already has the start of a shutter ? But any dome is complicated, particularly if you want it to rotate automatically to follow the sky. I have experience of my micro dome ?

I didn't use contact adhesive on my roof. I was surprised how easy it was to use the EPDM rubber roofing. I used clout nails to hold the edge down up under.

I'm just concentrating on the camera insulation and clamping plate ATM. I'll sort out the main casing and supports for the PCBs and focus motor later. Here are designs for the camera insulation and clamp plate. I'll print them in ABS so that they can be glued together.

Surely not!! It's not difficult to put EPDM onto a roof, just a matter of being careful and following the instructions. Far easier than roofing felt.

I think it would take an enormous amount of work to convert that to a viable dome observatory. A timber roll off roof observatory would be easier.

Been working on the clamping system design. I was originally thinking of fully insulating the cooler from the rest of the ASC but heat from the cooler could help with dew heating. The most important thing is to insulate the camera, it helps to keep everything else warm.

I don't think there's much more I can do tonight - I need to design and print a housing for the camera to hold it against the TEC and to insulate it both from the environment and particularly from the hot cooler face which is just 4mm away from the bottom of the camera casing. I estimate that the cooler surface is around 50-60°C. ATM only the weight of camera and lens is holding the camera against the Peltier TEC, probably sufficient but if the parts are held together I could turn the assembly on its side and see how much difference proper orientation makes to the efficiency of the cooler.

Been out for the evening but now back and have turned off the light in my living room (alias workshop!). Now capturing with 10s exposures and getting plenty of noise. But have cooling on at 12.4v and 1.2A and the sensor temperature is coming down. I think I need decent thermal insulation around the camera as it's drawing water out of the air and freezing it and the latent heat is stopping the camera cooling down more. I've put the zoom lens with aperture control on the camera and reduced the aperture to almost closed. There is light on the ceiling from the computer monitor, my moon clock and several LED displays. I'm taking 30s exposures with a gain of 144. Sensor temperature is about 14°C with cooling compared with 30°C without cooling and lots of noise. As can be seen, the noise is pretty well gone, with just a few hot pixels. The focus is out because the spacing was set for the bigger lens. (C v CS mount lenses.)

I have a feeling that adding extra aluminium into the thermal path is going to be counter productive because there is a noticeable difference in temperature between the aluminium of the cooler near the Peltier TEC and further out and yet more down the fins. The aluminium is about 6mm thick on the top plate so I would expect it to conduct well - far better than several inches of 3mm aluminium. Temperature difference between cold and hot sides of the TEC have meant I have been able to increase the voltage to 10v while still maintaining 1A of current. Think I'll swap my PSUs over so that I can run the TEC above 1A. The rest of the unit is drawing less than 0.5A.

Cooling on and camera temperature dropping nicely but it takes a while. Now running cooling at 9v and 1A and camera temperature is 9°C. Ice is beginning to form on the camera casing (currently open to the atmosphere - no thermal insulation). ATM I can't get the camera light tight and a 1s exposure is showing light. The noise is much less. I think I need to wait until dark to stop light getting into the camera unless I can find something to plug the camera with.

With the camera covered with a booklet to try to keep the light out and exposure increased to one second the temperature rose to nearly 30°C and lots of noise was seen. There is a bit of light leakage. Now to add cooling.

Working fine with cable connection. Running camera with short exposures and the sensor temperature is around 27°C without cooling other than convection from the exposed camera casing.

I think the way to go is to connect it with Ethernet cable and see what I've got the WiFi set to. WiFi in the router is turned off and I'm using the AP for WiFi as it has a much greater range. Anyway, I don't want too many things to get working at the same time so I'll stick with the Ethernet to test the cooling. I don't need WiFi until I mount the ASC on the observatory and even then I could use a wired connection if I mount it on the side of the roof.

I have all the bits connected up and trying to connect to the RPi. Initial attempt failed but I think the reason may be that I've installed a WiFi Access Point since I ran it last. I also need to look back through stuff to find out how I did things ?

Thank you Dave, I'll let you know. That would be ideal for the more remote mounting but I think if it works well with the TEC straight on the cooler I'll probably go with that.

The right cooler has arrived and is certainly a really large passive heat exchanger. It also has some very useful attachment screws with springs to hold the cooler on. I'm going to try the cooler directly on the TEC to start with and run it indoors (warmer environment) with the lens covered while capturing a long exposure giving maximum camera heating internally. I'll run the Peltier TEC off a second bench PSU and see how the cooling goes.

Haven't found that PV cell but I have found my box of lenses for widefield imaging. I have designs for 3D printed brackets for whichever aluminium pipe I decide to use and a support bracket for the larger diameter pipe. With over-engineering in mind, I think I shall use the thicker one. I can't really see any disadvantage. Before I stick the wind (and light level) measuring unit up in the air though I really need to work out how I'm going to connect it. As it is, it just connects to a computer via USB. The data logging and indoor instruments unit also connects via USB. Then there's the exterior temperature and humidity unit and the rain gauge to connect in. My earlier weather station design used 1-wire bus but with several of the 1-wire devices being no longer available I have abandoned that idea. I shall need to have a good think ? I plan to put the indoor unit in my observatory scope room where it can check temperature and humidity in there (more useful than in the house, I reckon). The display will be indoors. The observatory currently has a CAT6 megabit Ethernet connection but no USB connection to the house.

I'm waiting for a passive cooler for my all sky cam.

Trouble is there isn't enough room between lens and the camera window.

Removed old bit of vane and cut a new one from 0.7mm aluminium sheet and fitted it. This is actually a bit lighter than the piece of thin acrylic sheet I used before so moved it a couple of mm further out to balance. The photo-voltaic cell I thought I had has disappeared from the old weather station so I'll have to look for it (or something else).

I need to cut a new vane as the present one got broken - that's no problem (as long as I can get the old one out). I think I shall try the 35mm diameter x 5m aluminium pipe as the mast. If I find it's too whippy I can swap it for the 44mm diameter one. There will be less windage with just the weather station stuff on top and some movement shouldn't affect the wind measurements. Think I'll just make a new bracket and put the present unit on the mast top. I could add a light measuring unit on the other side of the mast. A photo-voltaic unit from an old garden light gives a volt or two which can be fed into an analogue input on the Arduino. Full scale analogue 5v gives 1023 so about 200 counts per volt - crude but adequate I think.

Thank you very much for the offer Do you mean this shape? Or this shape?

OK let's get over that - another cooler coming tomorrow. More thoughts on the design. I think I shall change the mounting for the ASC from the pole to mounting on the south side of the observatory roll off roof at the apex. This would tie in with mounting the Peltier TEC directly on the cooler which is easier overall I think. A 3D printed casing would fit over the camera and clamp the Peltier TEC between camera and cooler. This casing would also carry the focus motor and electronics boards. It would be screwed to the cooler and also be extended to form the mounting onto the wooden barge boards on the observatory roof. It may also extend upwards and take a push on dome assembly. I've looked into using an aluminium strip to connect the Peltier TEC hot side to the cooler but I think this has problems. I have an aluminium strip 40mm wide and 3mm thick which I think would be hard to bend and also a thin piece about 90mm wide but only 1mm thick. I'm not sure the shin sheet would conduct the heat well enough. So far so good but I don't think it's worth spending time designing printed parts until I've done some tests to see if any of this would work well enough. So it seem this project has ground to a halt until I get the right cooler.

Cooler arrived but it was the wrong one - had a fan - so I'm returning it and have ordered again. Just hope they send the right one this time. It's very rare that Amazon send the wrong item but now I have to rethink what I'm doing today. I was hoping to have the ASC working today.

I was puzzled by those slits. The blocks in my walls don't have them.