Peltier cooler for my telescope imaging camera
This summers project is to build a cheap Peltier cooler for my ZWO ASI290-MM camera. This camera is a specialist mono camera that I use with my telescope for Astrophotography. For lunar and planets this camera is superb. Can grab some really good high quality images from it. However, I also want to be able to use it for Deep Sky images too – Galaxies, Nebula’s and so on. For these objects, I need lots of exposures, and long exposures too. (By long, we’re talking about a few minutes at a time) The problem with this camera is that because there is no cooling, it will have issues with noise in the images. This is true for all cameras, but uncooled cameras get hot and that creates more noise.
The Cooled version of the camera costs over £1000, so this is rather a lot of money, but the advantage is that camera will cool itself down to -20°C, which means there’s very low noise compared to taking images at ambient temperature.
There’s a really handy feature that these cameras have. On the back of the camera there’s a set of threaded holes. These will make an idea place to put a cooling device. Indeed it’s been done before, here’s a couple of youtube links that show other builds.
I love the design used in the second video, and I think I can further improve on this design too. At least, that’s what I’m going to attempt to do.
The main think I didn’t like about the second video was that the plate was a little thin. This means that the plastic screws sit proud rather than being countersunk.
I’m also looking at the installation method and am wondering if there is a way of getting both the big heatsink, and easier installation. Not sure if that’s possible.
The final think is that I want my camera to live attached to the scope, so want to be able to plug in the power and control cable rather than having it hard wired.
So, what’s the plan?
Firstly, the project is going to rest on a 100mm * 100mm * 2mm Aluminium plate.
This will have holes drilled, so that I can screw to the camera.
Next, there will be 2mm holds, so that I can thread some 2mm threaded bar through the plate, heatsink and fan to hold everything together.
Next, I’m going to find a 6 pin connector of some description, so that I can plug a cable into the cooling unit.
The connector will have the following….
- Cooler +12v
- Cooler 0V
- Fan + 12v
- Fan 0v
- Thermal detector +
- Thermal detector –
The big part of this is that 6 sockets are required, and that the cooler should be able to transfer a large amount of power (5A ish)
The plug that I think would be perfect for this project would be a 6 pin PCI Express power connector. These are normally used on computer graphics cards to supply power.
https://uk.rs-online.com/web/p/products/2332769/?grossPrice=Y&cm_mmc=UK-PLA-DS3A-_-google-_-PLA_UK_EN_Connectors-_-Pcb_Connectors%7CPcb_Connector_Housings-_-PRODUCT+GROUP&matchtype=&gclid=Cj0KCQjw3InYBRCLARIsAG6bfMQgCdycIT3pxPTf5MxcIy6V5DMwVvSiZMjRDJjzpBiYvC4_X85wIoYaAuP3EALw_wcB&gclsrc=aw.ds
Here’s the socket.
https://uk.rs-online.com/web/p/pcb-connector-housings/2332826/
I’ll also need 2 switches. One for the fan and one for the cooler. I like the idea of being able to turn the fan on and off by choice.
These switches would be useful to have LED’s in place so that I can see if when they’re on and when there’s power.
For the power input, I’m thinking a simple 2 pin connector 2.5mm
https://uk.rs-online.com/web/p/dc-power-plugs/8787207/
And here’s a panel mount socket…
https://uk.rs-online.com/web/p/dc-power-sockets/7684419/
I’ve already got the thermal probe, will need to mount this in a project box. Then add a few wires to hook it up to the sockets.
On the cooler itself, I’d like to have a small project box, so hold the 6 way connector in place and to add a little protection for the wires.
Update: 25/05/2018
Just been a link to an instructable for how to make a cooler. I’d seen this before, but has forgotton about it. This is the idea of what I’m trying to achieve.
http://www.instructables.com/id/Peltier-Cooling-for-ZWO-Astro-Camera/
