Cheap cooling fan

[spaceboy]

As the Summer (cloud and rain) boredom has well and truly set in I figured there were a couple mods I could do to keep my hand in.

I had an off cut of foam from a previous DIY dew shield project

which I decided to use as a baffle for my 250PX to reduce any risk of observatory lighting entering the rear of the scope. I figured I may as well also put to use a spare cooling fan from an old PC tower I'd had lying around. There is some debate to the usefulness of fans in astronomy but given how warm my obsy can get in the summer months I figured any form of cooler air flow over the rear of the mirror is better than nothing at all. Fixing the fan also served as a way to secure the foam baffle in place by using the stock threaded holes often found on SW mirror cells. The foam also has the added advantage of offering some vibration control between the cell and the fan body and as a barrier to stop the cool air from just bouncing straight back off of the rear of the mirror.

To prevent any risk of vibrations as well as having some control over the fan speed I decided to buy a controller from ebay http://www.ebay.co.uk/itm/141745524193 which was Velcro-ed to the side of the ota for easy access. I had a couple of power connectors lying about from a previous DIY dew heater project for hook up to a 12V supply.

so in all the total cost of the mod is £3.90 and put some spares to good use, and kept me occupied for an hour.