It has been difficult keeping cool over the past week - very unusual in UK. A holiday (at home during lockdown) gave me the opportunity to work on one of many astronomical projects or pipedreams. One of these is how to keep an old CCD camera cool. The 1990s Meade DSI cameras use a passive cooling system, transferring heat via a 'cold finger' to a heat sink built into the rear shell of the camera body.

Following helpful advice, and subsequent encouragement, from the likes of David Dearden [http://deardencheapastro.blogspot.com/2014/05/cooling-meade-dsi-iic-with-peltier-chip.html, and another http://astromodifications.blogspot.com/2010/01/im-testing-this-now-by-adding-some-text.html] I milled off the back of my camera. When I say 'milled', I ground down the prongs with a dry stone and drill, and then filed...and filed...and filed...a good rub with wet n' dry produced a nice flat surface, even if I had lost my cool! I also used the back of my original DSI IC, which fits the Mk 2 camera.

Using one of those rather 'too good to be true' (cheap) DIY Peltier cooling kits from the internet, I proceeded to build the cooler. It does not add very much weight to the back of my SCT, together with a very neat thermostat which lets you regulate the temperature, and remind you how warm it is. To cut a long story short, after various approaches to securing the TEC chip, heat sink and fan combo to the camera body, I have gone with the tried and tested, if temporary approach, using rubber bands courtesy of our local postie. I'll stretch to cable ties but thought I might try some nylon bolts first. I'll add a few 'revisions' for anyone who is interested, although as David reminded me you can get much more camera using one of the new lower end TEC cooled CMOS cameras on the market these days.

The camera quickly cools to 4-5 degrees below ambient, but then slowly rises again, due to conduction and radiation through the casing - use of a cork mat has provided some insulation, which maintains the camera at ambient (4-5 degrees below its normal operating temperature. I've ordered a secondhand 8cm CPU heat sink and fan to replace the rather inadequate 4cm one supplied, which should help, and I may need replace the 'value' TEC chip with a better brand. Everything is a trade in terms of weight, price and efficiency. Anyway it has been fun...and that is cool.