Why do you need a dew controller?

[markus.a.bergh]

Why do you need a dew controller?

I've read that dew straps don't work without a controller but that has not been my experience.

So why do you need one apart from being able to control / regulate the temperature , the drain on the battery and draining your wallet ?

I've been hooking up a 12" (dewnot) strap to a car battery and it works great. It if gets too hot I'll disconnect it, but it hasn't yet and the temperature sensors inside the OTA tell me that its working well and not overheating. In fact it's working so well that I might get another one for the eyepiece/focuser.

But I'm no expert. So if you're just observing and only want to avoid dew, then is it OK to live without a controller?

P.S. I know you can build a controller (pulse width modulator ) yourself - but I'm not interested if its not necessary and besides, they might be cheaper but the cost adds up if you add more straps and need more controllers.

[Starkler (Geoff)]

Originally Posted by markus.a.bergh

So why do you need one apart from being able to control / regulate the temperature , the drain on the battery and draining your wallet ?

They are pretty good reasons. You COULD get by without regulation, but you would be overcooking any optics you are heating with it, and thats bad if you like crisp sharp images. Ideally you want to apply the minimum heat that prevents dewing.

[markus.a.bergh]

Thank you.

[leinad (Dan)]

A good question Markus. I was wondering the same.

Also, how less effective is just a dew shield. Or how effective is a dew shield compared to heater straps? Do these both apply differently only to refractors or cassegrains, newtonian scopes?

[Archy (George)]

Originally Posted by markus.a.bergh

Why do you need a dew controller?

I've read that dew straps don't work without a controller but that has not been my experience.

So why do you need one apart from being able to control / regulate the temperature , the drain on the battery and draining your wallet ?

I've been hooking up a 12" (dewnot) strap to a car battery and it works great. It if gets too hot I'll disconnect it, but it hasn't yet and the temperature sensors inside the OTA tell me that its working well and not overheating. In fact it's working so well that I might get another one for the eyepiece/focuser.

But I'm no expert. So if you're just observing and only want to avoid dew, then is it OK to live without a controller?

P.S. I know you can build a controller (pulse width modulator ) yourself - but I'm not interested if its not necessary and besides, they might be cheaper but the cost adds up if you add more straps and need more controllers.

I've used a dew zapper without a controller on my C8, but that was at home with 240v power and transformer.

On the field, I prefer to use a controller to regulate the temperature and avoid draining the battery too quickly.