Anti dewing system

[Tony G]

Just wondered if anyone has attempted to make an anti dewing system from a 12 volt electric blanket (not the whole blanket, just the insides).
Any advice would be appreciated.

Tony G

PS Don't do electronics, so if you do have any advice please type slowly so I can understand.

[Mike]

I know Chris has made his own home made dewing systems. As far as I know they are very easy to make and the heating elements are just a string of resistors soldered in parallel then encased in shrink wrap.

[Tony G]

Mike,
I think you were typing to fast the word "resistors" crept into your messege . Being a carpenter and now a construction manager 'resistors' and me have never crossed paths but hopefully Chris reads this and can shed a bit more light on the matter. Thank Mike.

Tony G

[Whitters]

Tried to make a controller and the wire'y resistor thingy, but being a software engineer I failed and went out and bought one insted.

[Ian]

I'm just turning over some ideas in my head for an eyepiece warmer, we could catch up at the next meeting and I can go over some basics if you like.

Paul, I'm disappointed in you mate. Giving up?  

[Ian]

and yes, I know, an eyepiece warmer. Wimpy observer, does it get a little cold for little ianykins...?

[JohnP]

Something like this.....

http://obs.nineplanets.org/dp/theory.html

John

[Tony G]

John,
thanks for that link, there are some diagrams that look like graffitti to me but the step by step guide would be quite useful if the blanket project does not work and what is helpful is that the author on the link seems to have typed everything slowly for the benefit of people like me.

Thanks again John.

Tony G

[Tony G]

Well I managed to make the anti dewing system for a fraction of the cost of the BC&F one and in the process have learnt a few skills like operating a sewing machine and negotiating with the wife that this was a major project, more important than unblocking the bathroom sink waste or catching the half dead mouse that the cat brought in.
This major engineering feat (to me that is) cost a total of about £13 and if i could work a sewing machine quicker would have taken 3-4 hours stripping the blanket and re-assembling it to the size required, and IT WORKS in the testing facility, (the kitchen table), and nothing fused so I take it that I re-wired it correctly.
So until the next cold & clear night.

Tony G

ps the BC&Ew is cheaper than the BC&F equivalent (BC&Ew is Blanket Cover & Electric wire)

[JohnP]

Cool..... or should I say hot.....! We will all know where to come at DSC if it gets a bit chilly.. & just think you could always connect it straight to the 12V of your car & slip it inside your sleeping bag for a bit of added luxury....

Seriously though - congratulations sounds like it will be a long exposure ToUcam next.

Cheers,  John

[Tony G]

John I don't think the blanket would fit anyone now it's only about 4" wide, but saying that I did buy two just in case it went wrong with the first one, so I can hopefully observe through a clear scope and keep warm from my power station (12 volt supply) with the second blanket.

Tony G

[Rocket Pooch]

Hi Tony,

I completely missed this thread somehow.

My dew heaters we're both easy to make, the simple one was £4 with now ability to vary the heat, this is a Peter Vassey design one.

The second one used a ic555 timer thingy and wa also simple to put together, providing you can solder, it cost £13 and supports upto 4 heater coils.

I have the plans to both if you want them when you decide to use the heated blanket next week for its intended purpose.

Chris