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Dew heater controller


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Hey guys ... I'm having a bit of bother trying to find a dew strap and controller for my 8 inch SCT. All the controllers i find have the cigarette lighter plug as the adapter. I don't use power tanks as my scope is always set up at the back of my house where i simply run an extension lead out to the scope. 

So what i'm trying to find, without it costing a fortune, is anti dew heater and controller that ends out in a standard plug (2 pin euro for me).

I've seen a few dew straps advertised as "no need for controller" because of their low wattage. Does anyone have any experience with these?

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Are we dealing with voltage here, Denmark like UK running 230 volts at your 2 pin euro plug,  our home made dew straps (like most I would expect) run at approx 12 volts from transformer/power supply thing or battery.  We do have some cigarette lighter plugs but our heaters run via phono plugs/sockets.

You would not want to connect a 12 volt dew strip directly to 230 volts, gets far to hot :icon_biggrin:

A good guide to home made heaters and control from IanL see his blog at Blackwaterskies

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3 hours ago, Mick J said:

Are we dealing with voltage here, Denmark like UK running 230 volts at your 2 pin euro plug,  our home made dew straps (like most I would expect) run at approx 12 volts from transformer/power supply thing or battery.  We do have some cigarette lighter plugs but our heaters run via phono plugs/sockets.

You would not want to connect a 12 volt dew strip directly to 230 volts, gets far to hot :icon_biggrin:

A good guide to home made heaters and control from IanL see his blog at Blackwaterskies

Yes... please what ever you do, do not attach a dew heater straight to 220V... it will light up faster than you think and possibly star a fire. You will need to use a power converter 220 VAC to 12 VDC, like this one: http://www.meanwell.com/webapp/product/search.aspx?prod=HEP-100  may others are available.
the same goes for all astro equipment. 12-13,8 V is the range you need to use. The above converter for example is 8 Amps, which is normally enough for all your stuff. If in imaging, you may want to use a separate converter for your camera's.
The cigarette lighter plugs are plain out worthless, but they are very easy to replace with normal 12 v plugs like RCA, banana plugs, 5,5/2,1 mm plugs or 3,5 mm jacks. A little soldering skill is useful, but learned in a few sessions.

Dew heater controllers are very easy to find on Google also:  http://www.kendrickastro.com/

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20 hours ago, Mick J said:

Are we dealing with voltage here, Denmark like UK running 230 volts at your 2 pin euro plug,  our home made dew straps (like most I would expect) run at approx 12 volts from transformer/power supply thing or battery.  We do have some cigarette lighter plugs but our heaters run via phono plugs/sockets.

You would not want to connect a 12 volt dew strip directly to 230 volts, gets far to hot :icon_biggrin:

A good guide to home made heaters and control from IanL see his blog at Blackwaterskies

Hi Mick ... I'm aware of the problems associated with connecting straight to a mains outlet, so no problems there. No, what i'm looking for is a heater and controller where the controller has a 12v dc power adaptor attached to it instead of the standard 2 meter lead and cigarette lighter adaptor. I just want something that'll plug into a mains outlet instead of a power tank. I'm well aware that there will have to be a 12v dc adaptor in there somewhere.

 

17 hours ago, Waldemar said:

The cigarette lighter plugs are plain out worthless, but they are very easy to replace with normal 12 v plugs like RCA, banana plugs, 5,5/2,1 mm plugs or 3,5 mm jacks.

Dew heater controllers are very easy to find on Google also:  http://www.kendrickastro.com/

I originally brought a 12v dc 3 amp power adaptor for my avx mount but upgraded it to a 5 amp version. I still have the 3 amp. Do you think a 3 amp adaptor would be powerful enough to run a heat strap to fit an 8 inch SCT?

And i've looked all through Kendrick's line......it's just that, hmm....well, for what they are, heat straps and controllers are outrageously overpriced....kendrick's line is up there with the best of them. I just can't get myself to pay those prices for something that was probably thrown together for less than 30 bob in a sweatshop!

It's strange...pet shops sell heat mats and heat strips in all shapes and sizes together with thermostats for less than 50 pound. Why should something that produces less heat and has less technique in it, be so much more grrh!

However I recognise i need something to combat dew! Up to now i have used a home made dew shield with a hair dryer taped at an oblique angle onto a small tripod that i position out of FOV but that blows cold air into the opening of the dew shield. It works very well although its' not ideal. More than once i've knocked it over when i've been moving about in the dark. Less clutter would be better.

 

 

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Hi Olsin,  these LED dimmers are popular as cheap controlers, used in the Blackwaterskies link above, you would have to make up your own cables with sockets you like, the dimmers are cheap and not always robust (if you use them get a spare or two)

In the Blackwaterskies link a spreadsheet for scope size may help calculate Amps, and you may be able to measure the ohms (resistance) of your existing strap, know the voltage and resistance (ohms) to get the Amps (I hope that's right)  your 3A adapter may be OK for your 8" scope.

Hope that's helpful,  mick

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On 10/17/2017 at 14:34, Mick J said:

Hi Olsin,  these LED dimmers are popular as cheap controlers, used in the Blackwaterskies link above, you would have to make up your own cables with sockets you like, the dimmers are cheap and not always robust (if you use them get a spare or two)

In the Blackwaterskies link a spreadsheet for scope size may help calculate Amps, and you may be able to measure the ohms (resistance) of your existing strap, know the voltage and resistance (ohms) to get the Amps (I hope that's right)  your 3A adapter may be OK for your 8" scope.

Hope that's helpful,  mick

 

Thanks Mick. Those LED Dimmers look ideal. I've just ordered 4 :thumbright: In the meantime i found another site that had a simple recipe for home made dew heaters using resistors and standard solid copper wire instead of the harder to acquire, nichrome wire. I've now made one for my 8" SCT and tested it using a 3-12v 3 amp regulated power supply that i've had kicking about for years and it works perfectly. Smooth even warmth over the entire length of the dew heater that is easily raised or lowered by dropping/increasing voltage. I ran it for 6 hours as a test and used an infrared thermometer gun to check the temp along the entire length. Give or take a half a degree it was pretty even for a home made device.

I brought a good supply of resistors from the local DIY electronic shop (their as cheap as chips so why not) and i'm now in the process of making dew heaters for my EP, diagonal and focal reducer. It's a massive saving with regards to buying way overpriced manufactured dew heaters.

Here's the link for anyone interested..

http://www.dewbuster.com/heaters-330ohm-resistors.html

 

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Fantastic Olsin,  we did ours when SGL was young and used Sheeny's guide from the Australian forum IceInSpace here and here,  we switched from resistors to nichrome (from ebay) easy to sandwich between 2" velcro.  Once on you need hardly any heat at all.

Good stuff, mick

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Thanks wookie, that's exactly what i've done...or going to do just as soon as my 12v LED dimmers turn up. Such a simple and inexpensive method that basically anyone can do. I'm glad i went with my instincts on not being tempted by the easy to acquire yet overpriced manufactured products.

 

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1 minute ago, Olsin said:

Thanks wookie, that's exactly what i've done...or going to do just as soon as my 12v LED dimmers turn up. Such a simple and inexpensive method that basically anyone can do. I'm glad i went with my instincts on not being tempted by the easy to acquire yet overpriced manufactured products.

 

I know the controller although takes a little longer to get here but for £1.76 you cannot grumble £2 for the resistors you will need more for the 8" a bit of cable 50p and gaffa tape £4 for the lot very easy and inexpensive.

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