Another Dew Heater

[Glenhuon]

I decided to make a dew heater for the 80mm refractor and after checking the parts box didn't have enough resistors to make the one on the IIS projects. So tried another one that was suggested elsewhere. The former is a section of 90mm PVC pipe and the heater wire was cut off a jug element that was handy. The wire is long enough to give a resistance of 12ohms so at 12 volts it draws 1 amp (12watts heat). A bit too warm but with a controller or a reduced voltage would be OK. The "sock" was bought from the local sewing shop for $1/mtr. A bit of gaffer tape on the top for added insulation and waterproofing and its done.
All being well I should get some extended viewing tonight without the darn dew spoiling things :)

Bill

[peter_4059]

Bill,

What did you use for the controller? It looks like the DSE K3072 controller mentioned in one of the other threads is no longer available.

ps did the heater work ok?

[Omaroo]

Excellent Bill. You could also use it to reheat tea when observing late! :thumbsup:

[Glenhuon]

No controller yet, just straight 12v. Thought it might have to be turned on and off manually but it was b***** cold out there tonight and I just left it on for the whole 2 hours.. Worked great, didn't get too hot and not a trace of dew on the objective :) I'll have to make another one for the 102mm, still got 2/3 of the jug heater left.
There's probably controller kits available from other suppliers, but failing that theres circuits on the web to build from scratch.

Bill

[Glenhuon]

Gee Chris! never thought about that, its about the right size to fit around my coffee mug, multi purpose :)

Bill

[peter_4059]

How about this one? $25 as a kit or $40 assembled.

[Terry B]

Very nice
I have also recently make a heating strap.
I went to tricky dickies and bought a little packet of nichrome wire for about $4.
I just concertinaed the wire up inside a piece of 50mm wide duct tape folded on top of itself. I then velcroed it to itself around my 120mm guide scope.
I'm powering it with a crappy 12v battery charger that came with a now dead drill. It got pretty hot until I put it on the scope but the scope seems to suck the heat away. It seems to work well although the charger gets pretty hot. Doesn't really matter if it cooks as there always seems to be spare chargers around the house from dead battery operated items.

[Glenhuon]

BTW Chris. Changing the plastic cell on the 80mm SurplusShed objective for an adjustable one worked a treat. Much sharper stars now. Heres Omega Cent. taken with the DSI tonight.

Bill

[Glenhuon]

That was what I tried at first Terry, but it melted the gaffer tape on testing, so this is the Mk2 version :)

Bill

[Terry B]

:eyepop:
Must have got pretty hot.
The tape I used is black material sort of stuff and seems OK with the heat.

[Glenhuon]

Think I have all the parts in the shed for this, next project coming up :)

Bill

[Omaroo]

Adjustable one??????

[Glenhuon]

I bought an Aluminium objective cell with colimation screws through an ad in the CN classifieds. Cost $80 landed from USA, but worth it for correcting the coma on the 80mm. The lenses fitted in nicely for diameter but had to make an 8mm spacer to allow the retaining ring to tighten properly. The mounting spigot fitted into the existing OTA tube perfectly too.

Bill

[AlexN]

Looks good! very professional finish too, despite it's duct tape, it looks very flashy!

well done.

[Glenhuon]

Duct tape is like the force Alex. It has a dark side and a light side and it holds the universe together. ;)

Bill