Quick and cheap secondary dew heater

[gooseholla]

Hi,

Made a dew heater for my controller today. Quick and simple. I used an A4 sheet of self adhesive foam from hobby craft for 80p. Matt black. Although any colour will do. Then some offcuts of flocking paper, self adhesive. Nichrome wire also. 

First, find out how much nichrome wire you need. Secondly, get an ellipse template - such as the one found in Kriege's dobsonian telescope book. Cut it to the size of your mirror, then make it smaller. Cut out the inside to allow for the stalk. Now transfer this to the foam, and make  a couple of them, sticking them together to add insulation. Don't throw out the inside circle bit - you'll have the basis of a nice observing eye patch, or to look like a pirate when walking to the shops...

Now keeping the foam flat, peel the backing paper off. This is to stick the wire to. Snake the wire across the thing, pushing it in firmly. The adhesive isn't enough to hold it permanently, especially with slight heating, it is only to help lay the pattern out. Once it is done, get three bits of tape and tape the wire and foam ring. Now get some flocking paper. Stick the ring to it and then go around folding the paper over it to cover the wire. 

Now go around and trim it up neatly if you did a crap job to start with... Only solder one of your connector wires on if you are going to install it with the stalk in-situ, or you won't get it on. A couple of dabs of something like epoxy will hold the unit to the back of your mirror (if you have that mounting tape to hold rear view mirrors to windscreens that might work better and be less messy). Make sure it isn't runny epoxy for obvious reasons. You'll have to push the heater down firmly to the back for a few minutes, as you can't clamp it. Make sure you don't touch the front of the mirror with your sticky fingers. Solder the other wire, run them across a vane and out of the tube. I cut about a 2cm wide strip of flocking paper just a bit longer than the vane and used this to hold the wires down. Sure it adds a bit to the width of one vane but nothing too much.

There you have it, a dew heater in a few minutes for a couple of quid. 

NOTE: As long as you have the wire correct or the control turned down so it doesn't get too hot, the wire won't burn through the foam or flocking paper. Anything too high and you'll have smoke and wrecked foam - I won't tell you how I know

John

[triton1]

Who said Astronomy was expensive,nice one

[gooseholla]

Exactly. My entire setup doesn't look the prettiest, but I've saved hundreds doing it myself. And so what if it is a bit ragged, it will be dark!!!

John 

[des anderson]

Well done,just brill Des

[Gina]

I've saved lots of pounds on bits and bobs but spent thousands on cameras and scopes

[gooseholla]

Probably cos not too may people can build a camera easily or cheaper

[mapstar]

Great efforts again John. 

[gooseholla]

If it works I might make a second one - the right size...  There is a tiny bit of over hang cos of the added velour, but nothing too major I suppose. measure fifty times, velour once, as they say... okay, no one says that.

John