Budget DIY Dew heater for my Dob

[knightrider]

I haven't done it yet as all the parts are on order.

I'm going to put together these items to heat the secondary mirror, finder scope, eyepiece, and maybe the eyepiece holder if I can get it to adapt on there somehow.

My plan is to use these items:






The Dimmer switch from eBay:
http://www.ebay.com.au/itm/LED-Light...00951172146%26
$3.78 each x 2 for two controllers. I will split each controller to do two heaters.

The Heaters from eBay:
http://www.ebay.com.au/itm/New-Warm-...47f89bb&_uhb=1
$4 x 2. Two pairs I'm ordering. Motorcycle grip heater pads. They come as a pair and they're flexible. I will encase these in a material pocket with velcro.

12v Accessory plug:
http://www.ebay.com.au/itm/Accessory...a44ce3b&_uhb=1

$10. We all know what this is for.

I also purchased 10m of twin core wire to make my cables and connecting leads out of for everything. $16
And a $30 Jaycar purchase for all the RCA connectors and RCA splitters to connect everything with.

So all up $72 roughly so far. If I can get this to work, it'll be a whack cheaper than purchasing the real things for quadruple this.

Let me know what you think...

[nebulosity. (Jo)]

Looks good, I'll be watching to see how it goes.

Jo

[mikerr (Michael)]

It should work out very well. Keep us informed of the outcome.

One or two of those heating pads might be good for a heated eyepiece case. Keep the eyepieces warm in-between turns in the scope.

Thanks for posting.

Michael.

[ZeroID (Brent)]

I'm using a 6 watt beer brewer warming pad on the Lunt just behind the Objective. Wrap a towel around it to slow heat loss and just plug it into the 240v. Cost about $10, works a treat.

[2stroke (Jay)]

Like the heating pads beats a homebrew resistor job to death and if it works well thats a nice price

[knightrider]

Update:

Well I've put it all together.

Here is the accessory socket and connecting RCA's. Honestly it would've been cheaper and easier to buy RCA cables. The gauge of the wire was a bit thick for the RCA connectors and were a pain to fiddle with.

All the connectors I soldered in.


Dimmer Switches and connectors and heat pads. I had to trim especially the secondary by 2/3 at least to get it to wrap around the stalk.



I just used velcro to fit the switches for now. I may screw them on later.


The heat pad is just taped on to the stalk and along the spider vein.


Wrapped around the Finderscope and focusser. I'll ditch the velcro pocket for now. I'll use a wide hair band or sweat band to keep them on and insulated for now.


The cables need neatening still.

As for the heat that the grips put out, the ones that I left large are noticeably warm even when turned up onto half.
As for the Secondary pad, it seems it does feel warm to touch even when turned right up, although it appears that the heat it does produce is being completely absorbed by the secondary stalk, and it keeps it warm to touch rather than the cool steel feel.

I only tested this in the living room and am yet to test it outside in the cool nights air. I am interested to see if the secondary temperature will be enough to keep it above dew point if it is able to keep the stalk just warm...?

I didn't end up using the 4th heat pad for the meantime.

[knightrider]

I trialed it the heaters out the other night. It was about 15 degrees. All the heaters kept them to a warm to touch temperature also with the secondary.

I think continued use will tell the story on the nights with heavy dew risk.

I also wrapped material hair bands around all of them to give them some insulation and keep the heat in.