polarity of astrozap heated dew shield

[Northern Soul man]

Hi to all, just wondering of the polarity of the phono plug on the end of an Astrozap heated flexible dew shield as I want to wire a simple cigar plug direct to the heated dew shield so as not to use a dew heater controller - its an 11" cpc Celestron scope has anyone got any experience with running a dew heater without the dew heater controller Thanks All Paul.

[Merlin66]

The polarity shouldn't matter - it's just a resistance circuit ( the centre pin is positive BTW)

It will only take as much current as it can - around 2A but you may still need to be able to control it by "pulling the plug" occasionally.

I've always used the controller....

[Northern Soul man]

Hi Merlin, thanks for the reply, just eager to get going - saving for a controller which is next on the list but wondered if it would be ok to run like this for a while, yes I understand I would have to pull the plug to regulate - but I can live with that for a while - Thanks again Merlin regards Paul.

[kirkster501]

Hi Merlin, thanks for the reply, just eager to get going - saving for a controller which is next on the list but wondered if it would be ok to run like this for a while, yes I understand I would have to pull the plug to regulate - but I can live with that for a while - Thanks again Merlin regards Paul.

Paul, depending on the length of your observing sessions (or whether you live in a swamp......?) you might get away with just a rolled up camping mat as a dew shield for a while and get your bank balance back in order. That's what I have done. Sure you ultimately need a Dew Controller some day but in my case I have not needed one just yet during three hour observing sessions.

Just a thought to save you some dosh.

Steve

[faulksy]

as said no polarity on them but you cant regulate the heat, you could always buy a pulse width modulator cost around £10 this what is used in a dew controller any way. maplins sell them part no 919d2p thats what i used in my home made controlers and work a treat, hope this helps

[Northern Soul man]

Hi Guys, thanks for the advice, just going on my previous experience with the Meade, didn't have any problems with dew just using a flexi un - heated dew shield, but the Meade was an 8" - I've got enough for a heated dew shield but no controller - so I thought wiring the heater direct to the power tank and just regulating it by pulling the plug for a while - think I may try the DIY route for now (Thanks Kirkster) and not very good with a soldering iron Faulksy - are they just wired in-line - knowing my luck I'd end up going Supernova - cheers all and regards Paul.

[Starlight 1]

I was looking at your post on the dew heater and it come to me that I had a heated car seat cover with a controll box and plug in the garage I got last year it still had the price on it 14.99 , I taking it out the cover and I am going to use it as a dew heater. So have a look round car shop may be the way to go .I will just add the controll has got on it 4 preset heat buttons with leds next to them so you can see the seting.