Dew strap + controller

[groberts]

For years using my rig near to the house and just adding a dew shield, I manage to avoid dew 99.9% of the time. 

However, I'm now intending to venture down the garden with a new AM5 + ASIair set-up to get a view of the north sky (my house is otherwise in the way!) and that will mean much more dew.  I can of course plug the dew strap directly into the ASIair plus but would like to have some control over the heat with a controller but they generally seem to require a dedicated DC power supply, which is just more 'stuff' and would prefer to avoid.

Can anybody recommend a dew controller that would work directly with the ASIair plus?

Graham    

[StevieDvd]

On the ASIAir (apart from the first version) the power ports can be set to control the dew strap power style, they just need a 2.1mm connection instead of a phono plug. I don't believe there is a non ZWO controller that can be controlled from the ASIAir.

 

 

[groberts]

7 minutes ago, StevieDvd said:

On the ASIAir (apart from the first version) the power ports can be set to control the dew strap power style, they just need a 2.1mm connection instead of a phono plug. I don't believe there is a non ZWO controller that can be controlled from the ASIAir.

 

 

Thanks, I thought about that - so you just vary the amp setting via the ASIair?  I wonder oif there's a maxium limit?

Graham

[StevieDvd]

A quick google found this page which may be of help. The ports when used for Dew straps are PWM and set as a percentage of voltage instead of just on/off.

[groberts]

I have (at last) purchased some Lynx 12v dew straps from FLO: 40cm (0.67Ah) + 20cm (0.33Ah) + 15cm (0,25Ah) and am about to start using them this autumn but have a few more questions before doing so.

The straps are all 12v with varying Ah ratings (see above), which I find confusing, I'm using main power to an AM5 mount, then on to the ASIair box:

1. At say 0.67Ah is this the really same as saying 0.67amps in order to assess the total power drawn from the ASIair, which I believe is max 6 amps?
2. As the ports are, as said, adjusted as a percentage, what should I set them at my given set-up? 

Graham     

  

[bosun21]

No they are not the same. Your 40cm at 0.67Ah is 8 watts. Therefore the current draw is 8 ÷ 12v = 0.66A.

The 20cm is 4 watts so divide 4 by the 12v equals 0.33A.

HTH

[PeterC65]

FLO have stated the wrong units on their website. When they say Ah (a measure of battery capacity) they really should say A (a measure of current), but the numbers are right. So ...

40cm is 8W so consumes 0.67A at 12V

20cm is 4W so consumes 0.33A at 12V

15cm is 3W so consumes 0.25A at 12V

I use these dew straps without a dew controller by the way, just running them directly off the 12V mount supply (from a main power supply).

 

[bosun21]

6 minutes ago, PeterC65 said:

FLO have stated the wrong units on their website. When they say Ah (a measure of battery capacity) they really should say A (a measure of current), but the numbers are right. So ...

40cm is 8W so consumes 0.67A at 12V

20cm is 4W so consumes 0.33A at 12V

15cm is 3W so consumes 0.25A at 12V

I use these dew straps without a dew controller by the way, just running them directly off the 12V mount supply (from a main power supply).

 

Has anyone informed FLO of this error? I was wondering what they were doing providing battery capacity.

[PeterC65]

I haven't mentioned it to FLO. I didn't notice the error when I bought my dew straps from them!

 

[groberts]

Oh, that makes more sense then, pity about the error, thought it didn't seem correct!

Any advice on using the ASIair Power Output % adjustment then please?

Graham

 

 

[bosun21]

You would just adjust the power outputs depending on how bad the dew is. Really bad 90 -  100% , mediocre then 50% , light dew then 20 - 30%. You will just have to tailor it to the results of keeping the dew at bay.

[PeterC65]

I don't have an ASIair. I take the view that full power will definitely stop the dew, will do no harm, and since I'm operating from a mains power supply, will not drain a battery.

[globular]

Too much heat can create air turbulence.
I run mine at around 40% most of the time. Only if the temperature drops very quickly do I up it to about 65%.