12 replies to this topic

[X-Lurker]

Hey all-

 

I'm in need of a couple of dew straps, but I have no idea what/where to get. I would like to use the DC output on my ASIAir Pro, but it seems like most of the straps have RCA cable? Also, I have no idea what size would be best for my 100 Esprit and a AT60MM guide scope? 

 

Thank you for your help,

Larry

Edited by X-Lurker, 31 October 2020 - 04:08 PM.

[Napp]

I assume the output of the ASIAir Pro is 12 volts?  If so it's very easy to replace the connectors on dew heaters.  You don't have to worry about polarity.  Dew heater sizes from almost all manufacturers are stated in the diameter of the glass.  Most also state the total length so you can compare it with the circumference of your scope tube.  Astrozap, Dew-Not, Kendrick and R-Sky all build good dew heaters.  Be aware that R-Sky is in Russia.  Shipping could take a month from R-Sky before the pandemic.  You can build your own dew heaters.  Refer to the following for the two approaches:

 

https://www.dewbuste...-resistors.html

 

https://www.dewbuste...r-nichrome.html

Edited by Napp, 31 October 2020 - 04:19 PM.

[X-Lurker]

Yes the output is 12v.

I'm a little confused on the size I would need for my Esprit because I'm not sure where to place the strap. Do I wrap it around the dew shield directly over the lens cell or on the OTA itself? If I wrap it around the OTA that would put it 3-4 inches away from the lens cell..

[Napp]

The dew heater wraps around the tube just behind the dew shield - not around the dew shield.  You will hear some other opinions but the manufactures size the heaters to go around the OTA and not the dew shield.  If you wrap it around the dew shield you are heating the air in front of the objective and not the objective itself.

Edited by Napp, 31 October 2020 - 05:45 PM.

[X-Lurker]

In case anyone is interested...

 

This was suggested to me by one of the members of the ASIAir Pro Facebook page https://astronomy-im...-splitter-cable and I ordered a couple of Dew Not straps as well, so fingers crossed!

[GeoffC47]

In case anyone is interested...

 

This was suggested to me by one of the members of the ASIAir Pro Facebook page https://astronomy-im...-splitter-cable and I ordered a couple of Dew Not straps as well, so fingers crossed!

I am moving my dew heater straps to my ASIAIR pro (AAP) as well, and have those connectors on the way. Found them at High Point Scientific for the same price.  

 

I decided to use the AAP for my dew heaters instead of my recently arrived Astrozap dual channel control since I discovered that in the 'power output' tab of the AAP app (version 1.5.1 firmware 6.92) you can select 'dew heater' from a drop down menu on any of the 4 output power ports. Making that selection opens up a slider that lets you select power from 0-100% for your heaters.

 

Bingo! The astrozap is still within the return window, so back it goes. HTH

[By-tor]

I'm using 2 USB, 5v dew heaters plugged into a 3.0 USB hub that's powered by my ASIAIR Pro that also adds USB 3.0 ports for other items and have no issues with dew or frost on my glass.

 

https://www.ebay.com...872.m2749.l2649

 

https://www.ebay.com...fMAAOSwJqpgBozL

 

https://www.ebay.com...872.m2749.l2649

[duderubble]

I'm using 2 USB, 5v dew heaters plugged into a 3.0 USB hub that's powered by my ASIAIR Pro that also adds USB 3.0 ports for other items and have no issues with dew or frost on my glass.

https://www.ebay.com...872.m2749.l2649

https://www.ebay.com...fMAAOSwJqpgBozL

https://www.ebay.com...872.m2749.l2649

Does the power input match the cables supplied with the asiair pro? It's hard to tell from the listing.

[stevel3o7]

How about plugging a dew heater control box (astrozap, orion, dewnote etc.) in to a single 12v output of the asiair pro? Is this to much amp draw from on of the AAP?  What is the max amp draw from a single 12v outlet on the AAP?

 

I like the idea of using the app to control the dew strap and y connector to control two dew strips. Just exploring options.

 

Thanks!

[Chaser of Photons]

How about plugging a dew heater control box (astrozap, orion, dewnote etc.) in to a single 12v output of the asiair pro? Is this to much amp draw from on of the AAP?  What is the max amp draw from a single 12v outlet on the AAP?

 

I like the idea of using the app to control the dew strap and y connector to control two dew strips. Just exploring options.

 

Thanks!

Max output is 3A (36W) per channel or 3A (36W) total distributed across all four outputs.  If you are going to push the output capability to max you would need (according to ZWO documentation) a 12V @5A (60W) power supply/source.

[HeavyJohnny]

Max output is 3A (36W) per channel or 3A (36W) total distributed across all four outputs.  If you are going to push the output capability to max you would need (according to ZWO documentation) a 12V @5A (60W) power supply/source.

Are these numbers accurate? I was under the impression the the ASI 294 mc pro pulls 5 amps alone for the cooler. Thenthrow in the eaf, guide camera and dew heaters.... am I pulling too much power off my aap? I never get any over voltage warnings.

[kel123]

Are these numbers accurate? I was under the impression the the ASI 294 mc pro pulls 5 amps alone for the cooler. Thenthrow in the eaf, guide camera and dew heaters.... am I pulling too much power off my aap? I never get any over voltage warnings.

ZWO recommends a 12V, 3A power supply for the camera. It does not even draw up to that.

According to ZWO, "It only needs 0.5A to cool the camera to 30℃ below ambient." And according to the ZWO power consumption graph, it needs 1.75A to cool it to 45 degrees below ambient which is its maximum cooling power. depending on your location or time of the you might not be drawing more than 1A in practice. The draw from the guide camera is not even half of that, given the maximum current through USB ports. The guide camera shouldn't draw more than 0.3A .

According to ZWO, the EAF draws only 0.5A.

Given the maximum power consumption of common dew heater strips using  the length of a dew heater for a 5" scope , it shouldn't be more than 1A  at maximum at maximum power.

So, you are not pulling too much power or it would have malfunctioned.

 

However, there is always need for tolerance. This why ZWO recommends a 3A adapter for a lot of devices that does not draw upward of 2A and why some dew heater controllers have channels that outputs up to 3A. This does not mean your dew heater draws close to that. 

[onesillyhatch]

anyone have success just plugging an astrozap dew strap into the asiair pro?  

 

Thanks